Catalytic C-H Bond Activation and Knoevenagel Condensation Using Pyridine-2,3-Dicarboxylate-Based Metal-Organic Frameworks.
Free full text in Europe PMC
Abstract
Free full text
Catalytic C–H Bond Activation and Knoevenagel Condensation Using Pyridine-2,3-Dicarboxylate-Based Metal–Organic Frameworks
Abstract
Three 1D coordination polymers (CPs) [M(pdca)(H2O)2]n (M = Zn, Cd, and Co; 1–3), and a 3D coordination framework {[(CH3)2NH2][CuK(2,3-pdca)(pa)(NO3)2]}n (4) (2,3-pdca = pyridine-2,3-dicarboxylate and pa = picolinic acid), have been synthesized adopting a solvothermal reaction strategy. The CPs have been thoroughly characterized using various spectral techniques, that is, elemental analyses, FT-IR, TGA, DSC, UV/vis, and luminescence. Structural information on 1–4 was obtained by PXRD and X-ray single-crystal analyses, whereas morphological insights were attained through FESEM, AFM, EDX, HRTEM, and BET surface area analyses. Roughness parameters were calculated from AFM analysis, whereas dimensions of small domains and interplanar spacing were defined with the aid of HRTEM. CPs 1–3 are 1D isostructural networks, whereas 4 is a 3D framework. Moreover, 1–4 display moderate luminescence at rt. In addition, 1–4 have been applied as economic and efficient porous catalysts for the Knoevenagel condensation reaction and C–H bond activation under mild conditions with good yields (95–98 and 97–99%), respectively. Notably, 1–3 can be reused up to seven cycles, whereas 4 can be reused up to five catalytic cycles with retained catalytic efficiency. Relative catalytic efficacy toward the Knoevenagel condensation reaction follows in the order 2 > 1 > 3 > 4, whereas 2 > 4 > 1 > 3 for C–H activation. The present result demonstrates synthetic, structural, optical, morphological, and catalytic aspects of 1–4.
1. Introduction
Development of porous heterogeneous molecular catalysts is a demand of current industrial research. Metal–organic frameworks (MOFs) frequently recognized as porous coordination polymers (PCPs) are materials with excellent crystallinity composed of metal ions/metal clusters with organic linkers.1−6 Switchable MOFs are a type of smart materials that undergo distinct and reversible structural changes upon exposure to the external stimuli, thus finding interesting technological application.7 The geometry of a ligand governs crystal topology of MOFs and tunes micro-to-nano crystal morphologies.8 For instance, the ZIF-MOF family offers excellent chemical and thermal stability and adjustable porous structures.9 Over past couple of decades, PCPs have drawn tremendous attention and established prodigious worldwide interest not only owing to versatile designability, excellent tunable porosity, structural diversity, miscellaneous topologies, and high surface areas but also due to their fascinating applications in waste water treatment,10−13 catalysis and gas storage/separation,14−17 chemical sensing,18−20 optoelectronic materials,21−26 heterogeneous catalysis,27−34 water oxidation,35,36 energy storage and conversion,37−40 luminescent materials,41−44 and so forth. CPs having metal nodes and a variety of bridging organic linkers comprise exposed active metal centers, thereby providing a high degree of metal dispersion for unambiguous catalytic applications.45,46 In addition, most emerging and advanced applications of crystalline PCP materials are heterogeneous catalysis.59−67 Because of their multicomponent nature, feasible functionalized catalytic active site PCP materials have been proved as ideal platforms for heterogeneous catalysis and they have been utilized in a wide range of chemical reactions with promising catalytic performance.56,82,83 CPs have demonstrated excellent morphology-dependent heterogeneous catalytic performance catalytic activities for a wide variety of organic reactions, viz., aldol condensation,57,58 Henry reaction,59−61 Michael addition, multicomponent reaction,62 C–H activation,47,63 Friedel–Crafts reactions,64 Tandem reactions,65 and Knoevenagel condensation.66−70 Moreover, the structural tunability of PCPs leads to the elegant tailoring of a chemical environment at catalytic sites, thereby causing chemo, regio-, stereo-, and/or enantio-selectivities.71−73 In addition, the crystalline nature of PCPs provides opportunity to well-disperse active sites at a molecular level, thereby favoring to the mechanistic studies.48−55
In particular to the Knoevenagel condensation reaction, a variety of heterogeneous catalysts have been used, that is, zeolites,74−78 clays,79−83 organic-functionalized molecular sieves, silicate–organic composite materials,84 and PCPs,30,85−89 which demonstrated vast significant advantages over homogeneous catalysts. Remarkably, it is noteworthy to mention that PCP-based heterogeneous catalysts are quite limited toward oxidative conversion of benzaldehyde into benzoic anhydride (C–H activation) which is a very advantageous reagent in organic synthesis,90−93 for instance, silyl ester’s lactonization,94−96 asymmetric esterifcations,97 and synthesis of peptides and drugs.98−100 Employing homogeneous catalysts, Knoevenagel condensation reactions and oxidative conversion of benzaldehyde into benzoic anhydrides involve various difficulties such as low catalyst loading, poor recyclability, tedious work-up process, longtime consumption, and catalyst contamination, whereas heterogeneous catalysts are easily recoverable and reusable and minimize the undesired waste.101−105
Additionally, pyridine-dicarboxylate and analogous linkers have been meticulously utilized in the construction of a variety of PCPs.109−119,156 Among pyridine-dicarboxylates, 2,3-pdca ligand has been least utilized toward production of PCPs possibly due to obstruction of its use as a bridging ligand.118,156 Notably, under hydrothermal/solvothermal conditions (Scheme 1),106−108 2,3-pdca rarely assumes a unique coordination mode via in situ mono-decarboxylation at the second position, thereby producing nicotinic acid,156 whereas 3,4-pdca transforms into isonicotinic acid.119 Remarkably, the present work entails in situ decarboxylation at the third position on 2,3-pdca to produce picolinic acid (pa) under the solvothermal reaction120 (Chart 1c and Scheme 2). Although 2,3-pdca-containing MOFs/CPs are documented in the literature, however these have seldom been used as heterogeneous catalysts especially in the Knoevenagel condensation reactions and oxidative conversion of benzaldehyde into benzoic anhydrides.63,121,122
2. Results and Discussion
2.1. FT-IR Spectral Analyses
The FT-IR spectrum of 1 displayed broad and strong vibration at 3418 cm–1 which may be ascribed to the existence of coordinated water molecules (Figure S19.1).124 Furthermore, the presence of the strong peaks at 1667 and 1587 cm–1 may be associated with the characteristic of asymmetric stretching (νas) vibrations due to the −COO– group, whereas the peaks observed at 1442 and 1394 cm–1 are attributed to symmetric stretching (νs) vibration of the −COO– group. Relatively larger separations >200 cm–1 between νas(COO–) and νs(COO–) indicate the monodentate coordination mode of the carboxylate group, whereas smaller separation <200 cm–1 suggests the chelating bidentate coordination mode of the carboxylate group.125−127 The presence of the corresponding Δν value >200 and <200 cm–1 in the same spectrum indicates both bidentate and monodentate −COO– coordination mode in the 2,3-pdca ligand which has further been authenticated by X-ray single-crystal analyses (vide supra). The other important absorption bands that appear in the IR spectrum of 1 are νC–H (2980 cm–1) and νC=C (1464 cm–1) (Figure S19.1).128 Peaks appearing in the far-IR region indicate the formation of Zn–N and Zn–O bonds.129 Likewise, 2 exhibited vibration at 3517 cm–1 owing to the coordinated water molecules along with characteristic vibrations associated with νas and νs −COO– groups at 1661 and 1555 cm–1 and at 1441 and 1379 cm–1, respectively (Figure S19.2).124,125 Weak vibrations present in the range 425–460 cm–1 may be attributed to Cd–N and Cd–O stretching vibrations.129 CP 3 shows vibrations at 3441 cm–1 (νH2O), 1583 cm–1 (νas–COO–), and 1369 cm–1 (νas–COO–) (Figure S19.3).124,125,128,130 On the other hand, the FT-IR spectrum of 4 displayed a vibration at 3238 cm–1 which may be attributed to the −N–H stretching band of quaternary amine (CH3)2NH2+. Furthermore, characteristic νas and νs bands of −COO– groups of 2,3-pdca appear at 1633 and 1592 cm–1 and at 1425 and 1382 cm–1 (Figure S19.4),130 having Δν value >200 cm–1 which indicates that the carboxylates of 2,3-pdca ligand are linked with Cu(II)/K(I) adopting bidentate and/or bridged bidentate coordination modes.129 Overall, the FT-IR data are consistent with the structure obtained from SC-XRD analysis.
2.2. Powder X-ray Diffraction Study
In order to check the structural identity and phase purity of 1–4, powder X-ray diffraction (PXRD) analysis was performed at rt (Figure S20). The PXRD patterns of 1, 2, and 4 closely match with the patterns simulated from their respective X-ray single-crystal diffraction data. On the other hand, the major peak profiles of experimental PXRD of 3 closely match with experimental PXRD patterns of 1 and 2. It indicates that CP 3 possesses the structure very similar to those of 1 and 2. Notably, the PXRD pattern of 4 varies from the rest of CPs 1–3 in terms of the appearance of peaks at a low 2θ angle (2θ = 8.12 corresponds to (2 0 0) reflection), and a higher intensity ratio suggests a different and more porous structural framework of 4. The relation of PXRD data and transmission electron microscopy (TEM) image has also been discussed in the Morphological Studies for 1–4 section (vide supra). The PXRD patterns of 1–4 recovered after catalytic reactions have also been obtained after 5 to 7 catalytic cycles (vide supra). Overall, the PXRD analyses of 1–4 are indicative of bulk sample purity.
2.3. Crystal Structure Studies
2.3.1. Structural Description of 1 and 2
Solvothermal reactions of 2,3-pdca with Zn(NO3)2·6H2O and Cd(NO3)2·6H2O in the presence of KOH afforded single crystals of [Zn(2,3-pdca)·(H2O)2] (1) and [Cd(2,3-pdca)(H2O)2] (2), respectively. CPs 1 and 2 are charge neutral 1D polymeric chains comprising fully deprotonated ligands 2,3-pdca2– (Figure Figure11c,d). Complexes 1 and 2 assume a quite similar structure wherein the metals (Zn2+/Cd2+) act as a node and 2,3-pdca2– serve as a linker along with two coordinated water molecules on each metal center (Figure Figure11a,b). Detailed crystallographic parameters for 1 and 2 have been listed in Table 1. X-ray single-crystal diffraction analysis reveals that 1 and 2 crystallize in the monoclinic P21/c space group and the asymmetric unit consists of one Zn(II)/Cd(II), one 2,3-pdca2–, and two coordinated H2O [Figure Figure11a–d, Table 1]. Each dianionic 2,3-pdca2– ligand was linked with three metal centers adopting two distinct coordination modes by N∧O chelating coordination to M(II) from one −COO– and M(II)–O–C–O–M(II) bridging coordination from the other −COO– group [M = Zn(II)/Cd(II); Mode-XII-μ3-(κ4N,O2:O3:O3), Supporting Information]. Two coordination sites have been occupied by two aqua ligands leading to a slightly distorted octahedral geometry about the metal center with symmetry codes: (i) x, y, z + 1; (ii) −x + 1, −y + 1, −z + 1; and (iii) x, y, z – 1 for 1, whereas (i) −x + 1, −y + 1, −z + 1; (ii) x, y, z + 1; and (iii) x, y, z – 1 for 2. Furthermore, carboxyl oxygen atoms are involved in intra- and intermolecular hydrogen-bonding interactions.
(a,b) Asymmetric unit of 1 and 2; (c,d) two types of cavities (square and ellipsoid shape) differing in dimensions along the crystallographic “c”-axis. Symmetry code for 1 (i) x, y, z + 1; (ii) −x + 1, −y + 1, −z + 1; and (iii) x, y, z – 1; for 2, (i) −x + 1, −y + 1, −z + 1; (ii) x, y, z + 1; and (iii) x, y, z – 1.
Table 1
| compound | 1 | 2 | 4 |
| formula | C7H7NO6Zn | C14H14Cd2N2O12 | C14H12CuKN3O8 |
| formula weight | 266.53 | 627.09 | 452.91 |
| crystal system | monoclinic | monoclinic | orthorhombic |
| space group | P121/c1 | P121/c1 | Pnma |
| a (Å) | 7.7081(4) | 7.8597(5) | 21.7641(13) |
| b (Å) | 15.6681(7) | 15.9234(10) | 17.4903(10) |
| c (Å) | 7.7483(4) | 8.0981(5) | 9.3685(5) |
| α (deg) | 90 | 90 | 90 |
| β (deg) | 113.824(2) | 114.849(2) | 90 |
| γ (deg) | 90 | 90 | 90 |
| V (Å3) | 856.04(8) | 919.67(10) | 3566.2(4) |
| Z | 4 | 18 | 8 |
| Dcalc (g cm–3) | 2.0679 | 2.2644 | 1.687 |
| μ (mm–1) | 2.879 | 2.383 | 1.51 |
| F(000) | 537.5656 | 605.1382 | 1832 |
| θmin, θmax (deg) | 2.87, 30.55 | 2.77, 30.57 | 25.7, 2.3 |
| hmin–max | –11, 10 | –11, 11 | –26, 26 |
| kmin–max | –22, 22 | –22, 22 | –21, 21 |
| lmin–max | –10, 11 | –11, 11 | –11, 11 |
| reflections collected | 2611 | 2824 | 3503 |
| data/restraints/parameters | 2611/0/163 | 2824/0/62 | 3503/594/286 |
| R1, wR2 [I > 2σ(I)]a | 0.026866/ | 0.037138/ | 0.119709 |
| R1, wR2 (all data)a | 0.037753/0.094958 | 0.041446/0.127273 | 0.1638/0.2423 |
| no. unique data | 2611 | 2824 | 3503 |
| no. Observed | 2241 | 2585 | 2320 |
| no. Variables | 163 | 62 | 286 |
| Rint | 0.0561 | 0.0388 | 0.229 |
| wR | 0.094958 | 0.127273 | 0.2423 |
| GOF on F2 | 0.760475 | 1.078909 | 1.094 |
| (Δρ)max,min (e/Å3) | 0.742389(−0.645688) | 2.328405(−4.14180) | 2.04(−1.15) |
| (Δ/δ)max, (Δ/δ)mean CCDC | 0.0003, 0.0000 | 0.0292, 0.0013 | 0.039, 0.000 |
One of the coordinated water molecules occupies an apical position with a longer Zn–O/Cd–O distance of 2.1651 Å/2.335 Å, whereas the other one assumes an equatorial position with a shorter Zn–O/Cd–O distance of 2.0065 Å/2.226 Å. One oxygen atom from −COO– and one pyridyl nitrogen atom from 2,3-pdca ligand chelate to one Zn(II)/Cd(II) metal having Zn–N/Cd–N and Zn–O/Cd–O bond distances 2.104 Å/2.313 Å and 2.056 Å/2.248 Å, respectively. The transoid angles around Zn(II)/Cd(II) lie in the range of 173.61–176.00°/169.24–176.44°, whereas cisoid angles range from 77.74–99.76° to 72.89–90.77° in 1 and 2 (Tables S13.1.3 and S13.2.2). Two types of M(II)···M(II) distances occur in a double-stranded 1D chain of 1/2; (i) the distance between M(II)···M(II) separated by bridging oxygen of the −COO– is uniformly 3.444 Å/3.629 Å and (ii) the M(II)···M(II) separated by pdca2– ligands is 6.433 Å/6.453 Å (M = Zn, Cd; Schemes 2 and 3, Figures Figures11b and and2b).2b). The structure of 1/2 reveals the presence of two sorts of cavities in their polymeric chain; square shape cavities having a dimension of 3.44 × 2.77 × 5.039 Å3/3.629 × 2.989 × 5.171 Å3 are created by two nearest M(II) centers separated by V-shaped bridged oxygens. The dimension has been measured by considering M(II)···M(II) and O···O distances. Ellipsoidal cavities of dimension (6.433 × 6.193 × 4.724 Å3/6.453 × 6.929 × 4.836 Å3 in 1/2) are formed between M(II)···M(II) centers separated by 2,3-pdca2– in the double-stranded chains and the dimension has been calculated by distances between M(II)···M(II) and O···O atoms, centroid–centroid distance of the aromatic rings of bridged 2,3-pdca2– ligands. In earlier reported CPs, Zn(II)···Zn(II) centers separated by bridging oxygen of the −COO– is uniformly 3.294 Å and (ii) the Zn(II)···Zn(II) separated by pdca2– ligands is 8.479 Å.
(a) Asymmetric unit of 4 and (b) dimeric unit of 4. Symmetry codes: (i) −x + 1, −y + 1, −z + 2; (ii) x, −y + 3/2, z; (iii) −x + 1, −y + 1, −z + 1; (iv) −x + 1, y + 1/2, −z + 1; (v) x + 1/2, y, −z + 1/2; (vi) −x + 1/2, −y + 1, z – 1/2; (vii) −x + 1/2, y + 1/2, z – 1/2; (viii) x, −y + 1/2, z; (ix) x – 1/2, y, −z + 1/2; and (x) −x + 1/2, −y + 1, z + 1/2. (c) Cap-stick view of a cage-shaped 3D cavity present in 4 along the crystallographic a-axis. (d) Demonstration of two Cu···Cu distances between adjacent molecules of helical and ellipsoidal cavities along crystallographic-b axes (hydrogen atoms are omitted for clarity).
2.3.2. Structural Description of 4
The molecular structure of 4 was determined by its X-ray single-crystal analysis (Figure Figure22). Crystallographic parameters and selected bond lengths and bond angles for 4 have been listed in Tables 1 and S13.3.1–S13.3.3, respectively. MOF 4 crystallizes in the orthorhombic crystal system with the Pnma space group. The solvothermal reaction of 2,3-pdca with Cu(II) in the presence of KOH followed by recrystallization in dimethyl formamide (DMF) leads to the formation of a 3D network {[(CH3)2NH2][CuK(2,3-pdca)(pa)(NO3)2]}n (4) via mono-decarboxylation from one unit of 2,3-pdca to form picolinic acid (PA–). By ignoring the disorder, an artificial lowering of the bond lengths with disordered atoms and high values of geometrical parameters has been observed. The counter cation (CH3)2NH2+ is present in the cage to neutralize the negative charge present in the overall complex 4. The (CH3)2NH2+ entity resulted from the decomposition of DMF under solvothermal conditions which is known in the literature.131 Incorporation of (CH3)2NH2+ as a counter cation in an anionic coordination network has previously been reported, although its source was not mentioned therein.132−134 Interestingly, the single-crystal structure of 4 revealed an unprecedented in situ decarboxylation of one carboxylate group from 2,3-pdca2– to produce picolinic acid (HPA). However, mono-decarboxylation occurred only from one unit of coordinated 2,3-pdca2– out of its two units linked with metal ions (Figure Figure22b,d). The Cu(II) centers assume distorted square pyramidal geometry completed by N2O3 coordination sites offered by 2,3-pdca2– and PA– ligands wherein 2,3-pdca2– adopts two distinct coordination environments; (i) one N∧O chelating site which also bridges through carboxylate oxygen and (ii) terminal coordination through 3-carboxylate. At the same time, PA– coordinated through the N∧O chelating mode to the Cu(II) center. The apical Cu–O bond distance of 2.246 Å is slightly longer relative to the basal Cu–O bonds. The Cu–N and Cu–O bond distances in the basal plane lie in the ranges of 1.966–1.978 and 1.957–2.245 Å, respectively, which are comparable to the analogous systems.131,135−139 Carboxylate groups and the pyridine ring are almost coplanar in 2,3-pdca. The adjacent distances between Cu(II)···Cu(II) separated by square and ellipsoid shape cavities in the 1D polymeric chain are 3.798 and 6.408 Å, respectively. A local coordination environment with about seven coordinated K(I) centers can be best described as a distorted tetragonal antiprism which consists of two 2,3-pdca2–, two PA–, and one nitrate ligand. The coordination mode adopted by the 2,3-pdca2– ligand in 4 can be classified as Mode μ4-(κ7N,O2:O2,O2′:O2′,O3:O3′).
The polymeric 3D framework of 4 wherein 2,3-pdca displays an unprecedented μ7-coordination mode further extends through intermolecular contacts. Another PA– ligand assumes coordination mode Mode-XXV μ2-(κ3N,O2:O2′). The K1–O distances are lying in the range of 2.670–2.941 Å, whereas K2–O distances range from 2.633 to 3.330 Å. Several ellipsoidal cavities with dimensions (7.437 × 7.830 × 11.872 Å3), (7.437 × 7.830 × 11.474 Å3), (3.829 × 5.694 × 11.872 Å3), (3.829 × 5.694 × 11.474 Å3), (11.872 × 11.474 × 9.940 Å3), (6.408 × 6.078 × 4.496 Å3), and (6.408 × 6.078 × 9.714 Å3) are present in 4 which have been measured by diagonal distances between centroids and centers separated by 2,3-pdca2–/PA– ligands (Figures Figures22 and and3,3, S12d and S14). The Cu(II)···Cu(II) centers are separated by two ways with distances 3.798 and 6.408 Å. The apparent 3D cages present in 4 with said dimensions are occupied by (CH3)2NH2+ cations through weak bonding interactions.
Cap-stick view of 4 along the crystallographic a-axis.
2.3.3. Supramolecular Interactions in 1, 2, and 4
The weak interactions through H···bonding, C–H···π, and π···π interactions lead to interconnectivity of double-stranded chains in 1 and 2, fabricating 2D layers in the bc-plane. Intermolecular O–H···O hydrogen-bonding interactions between oxygen atoms of water molecule and carboxylate groups lead to the construction of 2D repeated double-stranded chains along the crystallographic b-axis (Figures S2 and S7b). The distance between Zn···Zn/Cd···Cd centers separated by intermolecular hydrogen bonding is 5.393/5.430 Å. In 1, the inter- and intramolecular H···bonding distances lie in the range of 2.666–2.744 and 2.616–2.932 Å, respectively, whereas in 2, intermolecular H···bonding distances lie in the range of 2.663–2.744 Å. Notably, intramolecular hydrogen bonding is not observed in 2. Intermolecular C–H···π interactions form zigzag infinite parallel chains with hexagonal cavities both in 1 and 2 lead to a 2D network along the crystallographic b-axis having a dimension of 3.857 × 4.177 × 6.804 Å3 measured between O(2)···O(2), O(4)···O(4), and O(7)···O(7) in 1 (Figures S2–S4) and a dimension of 4.338 × 4.482 × 7.064 Å3 measured between O(3)···O(3), O(5)···O(5), and O(1)···O(1) in 2 (Figures S9–S11). In spite of a similar structural framework in 1 and 2, the intramolecular π···π stacking distances are lightly different [3.220, 3.243, and 3.373 Å in 1 and 3.354 and 3.391 Å in 2] while none of these entails intermolecular π···π stacking interactions. The centroid–centroid distances between two parallel aromatic rings of bridging pdca2– are 4.725 and 4.836 Å, respectively, in 1 and 2, whereas centroid–centroid distances between intra- and interchain six-membered aromatic rings are 4.724 and 5.372 Å in 1 and 4.836 and 5.486 Å in 2. The nearest Zn···Zn separation in 1 is 3.444, whereas in 2, the adjacent Cd···Cd distance is 3.629 Å (Scheme 2). Slightly longer distances in 2 may be due to larger ionic radii of Cd(II) in comparison with Zn(II). Distances between μO(1)···μO(1) in 1 and 2 are 2.777 and 2.989 Å, respectively. Notably, intra-/intermolecular H···bonding interactions involve all oxygen atoms of 1 and 2 which contribute significantly toward stability of intermolecular chains (Table 2). Prominently, these compounds contain both the Lewis basic (the noncoordinated oxygen atoms) and acidic centers (coordinated Zn(II)/Cd(II) ions) and coordinated water molecules as the potentially good leaving group in the same unit that enables these systems to find potential application as a bifunctional catalyst (Figure Figure44). On the other hand, supramolecular assemblies in 4 through intermolecular N–H···O (2.827 Å) weak interactions between 2,3-pdca2– carboxylate oxygen and N–H of the dimethyl ammonium cation lead to 3D extensive chains (Figure S18). The intermolecular C–H···π distances were observed in the range of 2.473–2.879 Å (Figure S13), whereas intermolecular π···π stacking interaction distances occurring between pyridine rings of 2,3-pdca2– are observed to be 3.343 Å (Figure S17).
(a) Cap-stick view of the 2D double-stranded chains incorporating dimeric 1 between two layers. (b) Inter- and intramolecular H···bonding interaction in 2 measured from the crystallographic a-axis. (c) 3D view of 4, resulting from O–H···O hydrogen bonding with a dimeric complex along the crystallographic b-axis.
Table 2
| D–H···A | D···H | H···A | D···A | ![[for all]](/corehtml/pmc/pmcents/x2220.gif) DHA |
|---|---|---|---|---|
| 1 | ||||
| O7-Hc···O6 | 0.82(3) | 1.82(3) | 2.6149(18) | 165(3) |
| O7-Hd···O6 | 0.82(3) | 1.92(3) | 2.7451(19) | 177(3) |
| O4-Ha···O5 | 0.75(3) | 2.03(3) | 2.7749(19) | 173(3) |
| O4-Hb···O2 | 0.82(3) | 1.85(3) | 2.6658(17) | 173(3) |
| 2 | ||||
| O5-Ha···O4 | 0.8700 | 2.03(2) | 2.753(3) | 140(3) |
| O1-H1a···O6 | 0.8700 | 1.895(9) | 2.748(3) | 166(3) |
| O1-H1b···O6 | 0.8700 | 1.913(7) | 2.668(3) | 144.4(9) |
| 4 | ||||
| N1S-H1Sd···O6 | 0.92 | 1.939(14) | 2.830(14) | 162.4(4) |
| N1S-H1Se···O6 | 0.92 | 1.939(15) | 2.830(14) | 162.4(4) |
2.4. Morphological Studies for 1–4
The morphological information was acquired for straightforward comparison of surface structures of CPs/MOF 1–4 so as to rationalize their distinct optical and catalytic behavior. Shape and microstructure of the resulting 1–4 have been investigated via scanning electron microscopy (SEM) (Figure Figure55 top; Figures S25–S28). To have deeper insights, SEM, TEM, and atomic force microscopy (AFM) analyses for 1–4 have been comprehensively illustrated. SEM, TEM, and AFM analyses revealed fairly appealing and idiosyncratic external morphological behavior by 1–4 (Figures Figures55 and and6).6). SEM images of 1–4 display homogeneous nanocrystallites aggregated with an excellent pore size in the clusters. CPs 1–4 are shown as crystalline materials through SEM images with an elongated block shape and particle sizes of about 30, 3, and 15 μm for 1–3, respectively. The morphological view of 1 displays interconnected crystalline fluffy (feathery) layered sheets (Figure Figure55, top 1), whereas SEM images of 2 show elongated unruffled nanorods with an approximate individual length ranging from 300 to 500 nm having uniform diameters of 20–40 nm. Moreover, SEM images of 3 exhibit little bent uniform layer with obvious small pores. Notably, 2 displayed an irregularly layered fibrous array with a larger pore size relative to that of 1 (Figure Figure55, top 2). In sharp contrast, SEM analysis of 3D MOF 4 exhibited flower-like porous morphology with granular clusters (Figure Figure55, top 4). The hierarchical structures in 1–4 are bound to possess a larger specific surface area capable of absorbing substrate(s) or facilitating heterogeneous catalytic activity to enable these materials as catalysts. In addition, the EDX analyses reveal the presence of C, N, O, and M with the respective weight ratio of 35.4, 10.3, 31.2, and 23.1 (M = Zn, 1), 37.2, 16.4, 39.5, and 6.9 (M = Cd, 2), and 32.8, 8.9, 41.4, and 16.9 (M = Co, 3), whereas C, N, O, K, and Cu elements with the respective weight ratio of 29.3, 37.2, 29.5, 7.8, and 26.2 (4) (Figures S29–S32). Overall, the EDX analysis strongly supports successful synthesis of 1–4.
SEM (top) and HRTEM (bottom) images of 1–4.
AFM images of 1 (a,e), 2 (b,f), 3 (c,g), and 4 (d,h).
In addition, TEM analysis of thin films of 1 and 2 revealed typical flat sheet morphologies and apparently visual cavities (Figure Figure55 bottom 1 and 2). Interestingly, despite structural resemblance, the TEM images exhibited different porous surfaces of 1 and 2 along with considerable liaisons among the arrays. The HRTEM image of 1 exhibited the interplanar d-spacing of 0.705 and 0.392 nm which corresponds to the respective (1 0 0) and (0 4 0) lattice plane of a monoclinic unit cell of [Zn(pdca)·(H2O)2]n. The origin of these fringes in the HRTEM images is clearly related to the PXRD data of 1. In the PXRD analysis of 1 (Figure Figure55 bottom 1), major diffraction peaks at 2θ values are 11.286, 12.543, 16.904, 17.757, 21.113, 21.152, 21.798, 22.683, 23.937, 25.969, 27.530, 31.209, 32.577, 33.023, 34.313, 34.518, 34.593, 35.484, 36.669, 36.702, 38.144, 40.075, 42.234, 42.311, and 43.456 which may be assigned to the reflection of (0 2 0), (1 0 0), (−1 2 0), (−1 2 1), (0 −3 1), (−1 3 0), (1 −1 1), (0 4 0), (1 −2 1), (0 −4 1), (−2 0 2), (−1 5 0), (−1 −4 2), (1 −1 2), (0 6 0), (1 −2 2), (2 −2 1), (−3 1 1), (−1 6 0), (−1 −2 3), (−3 2 2), (2 −4 1), (−3 1 3), (0 −7 1), and (−3 2 3) crystal planes (Table S14.1). Likewise, the HRTEM image of 2 displayed crystalline nanorod-shaped crystals and exhibited fringes having the interplanar d-spacing of 0.367 nm corresponding to the (0 0 2) lattice plane of a monoclinic unit cell of [Cd(pdca)·(H2O)2]n (Figure Figure55, bottom 2). The positions and relative PXRD peaks of 2 at around 2θ = 11.104, 12.401, 13.259, 13.593, 17.253, 20.845, 24.204, 25.426, 26.505, 27.785, 29.545, 30.721, 31.712, 32.018, 33.717, 35.050, 35.950, 36.367, 37.100, 37.845, 38.419, 39.488, 40.639, 41.859, and 43.62 which may be apportioned to the reflection of (0 2 0), (1 0 0), (0 −1 1), (−1 1 0), (−1 2 1), (−1 3 0), (0 0 2), (−0 −4 1), (−2 0 2), (−1.–3 2), (0 −3 2), (−1 5 0), (1 0 2), (−2 4 1), (−2 4 0), (1 −5 1), (0 −6 1), (−1 6 1), (−3 2 2), (−2 5 0), (−0 −2 3), (2 −4 1), (−3 1 3), (−3 2 3), and (2 −2 2) crystalline lattice planes, respectively (Table S14.2). The CP 3 comprises small particle and crystalline morphologies in its HRTEM images which shows an interplanar d-spacing of 0.4068 nm consistent to the (1 1 1) lattice plane of a monoclinic system (Figure Figure55 bottom 3). Positions and the relative PXRD diffraction peaks of 3 are more or less matching with those of 1 and 2. The positions and the corresponding PXRD peaks of 3 at about 2θ = 12.187, 13.366, 14.038, 14.687, 17.061, 17.437, 20.425, 21.895, 23.155, 23.254, 24.392, 24.515, 25.576, 29.363, 29.392, 29.622, 30.361, 30.438, 30.517, 30.921, 33.446, 34.260, 34.358, 35.271, 35.294, 35.588, 37.139, 37.242, 38.539, 38.828, 38.894, 39.016, 39.195, 39.776, 39.819, 39.837, 40.521, 40.585, 41.129, 41.365, 41.538, 42.261, 42.263, 43.481, 43.595, 43.738, 43.790, and 43.803 may be ascribed to the reflection of (−1 0 1), (1 0 1), (0 −1 1), (−1 1 0), (0 0 2), (1 −1 1), (0 −1 2), (−1 −1 2), (−2 1 1), (1 −1 2), (−1 2 0), (−2 0 2), (−1 2 1), (−3 0 1), (−1 −2 2), (−2 2 0), (−2 2 1), (1 −2 2), (1 −1 3), (3 0 1), (−2 2 2), (−3 1 2), (0 −2 3), (−1 3 0), (2 −2 2), (2 −1 3), (−3 0 3), (−3 2 1), (1 −1 4), (4 0 0), (−3 1 3), (−1 −3 2), (−2 3 0), (−2 3 1), (−2 −1 4), (1 −3 2), (−4 1 0), (2 −3 1), (−4 0 2), (2 0 4), (−2 3 2), (4 −1 1), (1 −2 4), (−1 −3 3), (−1 0 5), (2 −3 2), and (−3 2 3). Notably, the HRTEM image of 4 shows a more compact surface which may be ascribed to the lattice (CH3)2NH2+ cations present in the cavities. HRTEM images of 4 exhibit the interplanar d-spacing of 0.386 nm which corresponds to the (2 2 2) lattice plane of an orthorhombic unit cell of {[(CH3)2NH2][CuK(2,3-pdca)(pa)(NO3)2]}n (Figure Figure55 bottom 4). The PXRD pattern of the 4 having 2θ = 8.118, 9.564, 10.107, 10.704, 11.451, 12.977, 14.429, 16.278, 18.845, 20.293, 20.627, 21.249, 21.503, 23.019, 23.079, 24.521, 24.702, 24.725, 24.79, 25.065, 25.584, 25.596, 27.19, 27.261, 27.32, 27.502, 27.832, 27.89, 27.959, 29.435, 29.74, 29.80, 29.894, 30.185, 30.263, 30.483, 30.529, 30.537, 30.645, 30.651, 30.702, 32.033, 32.175, 32.401, 32.461, 32.499, 34.643, 36.134, 36.855, 37.472, 38.35, 41.265, 41.959, 41.963, 42.596, 45.129, 48.779, and 49.715 which may be attributed to the reflection of (2 0 0), (2 1 0), (0 2 0), (0 1 1), (1 1 1), (2 2 0), (1 2 1), (4 0 0), (4 0 1), (0 4 0), (2 0 2), (2 1 2), (0 2 2), (2 2 2), (5 1 1), (6 0 0), (1 3 2), (5 2 1), (3 2 2), (4 0 2), (4 1 2), (3 4 1), (0 5 1), (5 3 1), (3 3 2), (1 5 1), (4 4 1), (0 4 2), (5 0 2), (4 3 2), (2 0 3), (5 2 2), (3 5 1), (2 1 3), (7 0 1), (5 4 1), (6 3 1), (3 4 2), (0 6 0), (1 2 3), (7 1 1), (6 4 0), (1 5 2), (1 6 1), (4 4 2), (0 3 3), (4 2 3), (7 2 2), (5 2 3), (6 4 2), (6 1 3), (7 1 3), (5 6 2), (4 0 4), (1 6 3), (5 2 4), (5 4 4), and (4 5 4) lattice planes of the nanocrystallites confirm well with its structure (Table S14.4).
AFM studies were also pursued to quantify the minimum and maximum values of precipitate size and accumulation pattern of 1–4. Momentarily, the surface roughness of the samples was characterized by AFM and examined following the existing literature procedure.140−142 The AFM image of 1 reveals uniformly packed polycrystals with a size of the crystals in the range of ~30–50 μm (Figure Figure66a,e). Moreover, the micelle-like morphology specifies that 1 has a tendency to self-aggregate and further assemble into the crystalline structures. The CP 2 exhibits polymeric, spherical, granular, and porous domains which are clearly visible in the AFM image. These porous and granular structures may provide an increased surface area in 2 for catalytic applications (Figure Figure66b,f). Furthermore, the AFM image of 3 exhibits the formation of a well-established crystalline material which gets converted into twisted ciliated fiber-like morphology spread over the film (Figure Figure66c,g). The AFM image of 4 demonstrates roughly porous and shaggy layered morphologies having a very small uniform granule-like surface (Figure Figure66d,h). The 2D and 3D maps of 1–4 are also given in Figure Figure66 which indicate different surface morphologies. Average roughness (Ra) obtained from the films of 1–4 is 0.28, 2.52, 0.32, and 2.06 nm, respectively. Moreover, section analysis of the 2D images across the line in 1–4 affords the average tube diameter of around 12–15 nm (Figures S37–S41). The root mean square (rms) roughness (Rq) has been calculated to be 0.332, 2.71, 0.328, and 2.17 nm for 1–4, respectively (Figure S41). The low-to-high values in rms roughness are probably ascribed to the noncovalent intermolecular interactions on the surfaces of the polymers 1–4.143−146 As Rq is more sensitive to the peak and valley relative to that of Ra, typically Rq is 3 to 15% higher than Ra in these materials. A smaller roughness is associated with greater density and finer precipitates, whereas larger precipitates tend to increase the roughness value (Ra = 0.28–2.52 nm in 1–4). Overall, the SEM, TEM, and AFM analyses strongly suggest diverse structural morphology and porous surface of 1–4. The different intermolecular interactions may be responsible for morphological disparities in 1–4.
2.5. UV/Vis and Luminescent Spectral Analyses
Electronic absorption spectra for the suspended particles of 1–4 have been recorded in DMF (Figure S22). CPs 1 and 2 comprising diamagnetic Zn(II) and Cd(II) metals exhibited broad absorption bands at 286 and 287 nm, whereas 3 and 4 involving paramagnetic Co(II) and Cu(II) metals displayed bands having the absorption maximum around 289 nm. Therefore, observed absorption bands for 1–4 may be assigned to the ligand-centered transitions. It has been well-established that d10-transition metal complexes reveal fascinating luminescence properties.147,148 Hence, the solid-state photoluminescent behavior of 1–4 was also investigated at rt. CPs 1 and 2 encompassing d10-metal centers and conjugated organic ligands were expected to serve as facilitating inorganic–organic hybrids for prospective application as chemical sensors and in photochemistry.149−153 Notably, 1–4 exhibited moderate luminescence in the solid state.154 CPs 1–3 showed emission spectra having maxima at 398, 390, and 385 nm along with a shoulder peak at 421, 414, and 422 nm, respectively, upon excitation at their respective wavelengths (286–289 nm), whereas 4 displayed an emission band at 387 nm (λex, 289) along with a shoulder peak at 424 nm, respectively (Figure S23). The emission of 1–4 may be ascribed to the ligand-centered transitions and/or ligand-to-metal charge-transfer transitions.118,155−160
2.6. TGA and DSC Analysis of 1–4
To further assess the thermal stability of 1–4, thermogravimetric analysis (TGA) was performed on crystalline samples from 40 to 800 °C under a nitrogen atmosphere at a heating rate of 10 °C/min (Figures Figures77a and S21). A weight loss of 8.49% until 132 °C followed by another weight loss of 7.37% until 228 °C was observed for 1 which corresponds to the release of trapped and coordinated solvent molecules (calculated 13.54%). The loss of coordinated water molecules in 2 was completed by 169 °C with a weight loss of 9.38% (calculated 11.48%). In 3, a weight loss of 14.23% was occurred between 40 and 133 °C which is consistent with the loss of coordinated water molecules (calculated 13.84%). The rest of the framework remains thermally stable up to ~300 °C; thereafter, the desolvated framework starts decomposing the organic components and completes by ~460, ~417, and ~430 °C for 1–3, respectively. Compounds 1–3 exhibit similar decomposition processes which corroborate well with their structures (SCXRD and PXRD). Notably, the thermogravimetric histogram of the 4 does not exhibit any inflexion point before ~216 °C, which indicates its good thermal stability and strongly supports the lack of water molecule(s) [crystalliferous, lattice, or coordinated (Figures Figures77a and S21)]. Exceeding 220 °C, it was sharply decomposed by losing almost entire organic 2,3-pdca2– ligands with a weight loss (wt loss) of 53.99%. The remaining dark-brown scorched compound (unidentified) is obtained at 800 °C, which may be the metal oxides or metal carbonates. Overall, TGA analysis indicates good thermal stability of 1–3 and excellent thermal stability of 4.
TGA (a) and DSC (b) profile of 1–4.
In addition, DSC curves for 1–3 exhibited endothermic peaks followed by exothermic peaks (collapse/desolvation) of the framework (Figures Figures77b and S22). The values of ΔHf (J/g) and ΔSf were calculated from DSC endothermic peaks (DTGmax = 128 °C; ΔH = +181.2 J/g, ΔSf = 1.42 and DTGmax = 210.8 °C; ΔH = +185.8; ΔSf = 0.88; DTGmax = 320 °C; ΔH = 21.36 J/g, ΔSf = 0.067) for the first stage while an exothermic peak (DTGmax = 378.18, 552.49 °C, ΔHm = −1687 J/g, ΔSf = −3.63) for the second stage for 1. In contrast, 2 displays an endothermic peak (DTGmax = 165 °C; ΔHf = +154.9 J/g; ΔSf = 0.94) in the first stage and an exothermic peak (DTGmax = 388.93, 569.13 °C, ΔHm = −4118 J/g; ΔSf = −8.59) in the second stage. On the other hand, ΔHf and ΔSf for 3 have been calculated from endothermic peaks (DTGmax = 174.9, 366.7, and 519 °C; ΔH = 27.85, 65.83, and 36.63 J/g; ΔSf = 0.16, 0.18, and 0.071) in the first stage and (DTGmax = 337.80, 452.55, and 542.58 °C, ΔHm −730.6 J/g, ΔSf = −1.64) in the second stage. Additionally, 4 displayed a sharp endothermic peak at 257.7 °C followed by breakdown of the framework. The ΔHf and ΔSf for 4 were calculated from an endothermic peak (DTGmax = 257.7 °C; ΔH = +198.6 J/g, ΔSf = 0.77) for the first stage while in the second step, DTGmax = 401.16 and 564.59 °C, ΔH = −3015 J/g; ΔSf = −6.24. Overall, the DSC studies suggest a better stability of 4 over 1–3, whereas 1–3 follow the stability order 3 > 2 > 1 (Figures Figures77b and S22). The greater stability of 4 over 1–3 is also associated with the absence of coordinated water molecules in 4. Moreover, intermolecular associations may be the major factor of stability order 3 > 2 > 1.
While correlating DSC studies with the crystal structure, it can be stated that the framework structure converts from stable six-coordinated distorted Oh to less-stable four-coordinated Td geometry upon removal of two water molecules; hence, the process is endothermic in 1–3. Eventually, the remaining dark-brown scorched compound (unidentified) obtained at 800 °C may be the more-stable metal oxides or metal carbonates; hence, this process is exothermic. On the other hand, DSC of 4 shows one endothermic peak at 257.7 °C which may be attributed to the conversion of more-stable to less-stable species upon removal of lattice solvent/guest molecule followed by exothermic breakdown of the framework to attain metal oxides/carbonates.
2.7. Catalytic Studies on 1–4
The lability of ligands provides coordinately unsaturated active catalytic centers to carry out various catalytic reactions. The Knoevenagel condensation and C–H activation reactions are one of the most studied heterogeneous catalytic reactions performed for porous and framework materials of various metal centers, that is, Co, Cu, Zn, Ag, Cd, In, and so forth. The PCPs connected to several flexible ligands containing distinct aromatic rings are appropriate scaffolds for such catalytic reactions because metal centers exhibit variable oxidation states and coordination numbers.161 The Knoevenagel reaction is well-known not only as a weak base-catalyzed model reaction but also as a C–C bond formation reaction.89,162−166 In the present work, catalytic synthesis of 2-benzylidenemalononitrile has been chosen mainly because these intermediates are often used in polymers, perfumes, cosmetics, fine chemicals, pharmaceuticals, and drugs.141,182,185−191
2.7.1. Activation Method
Catalysts 1–4 were heated in an oven at 100 °C for 24 h under vacuum and a N2 atmosphere to remove the air/solvent molecules from the pores of CPs. The heating temperature was selected considering thermal analyses so as to avoid structural rupture.
2.7.2. Knoevenagel Condensation Reaction Catalyzed by 1–4
The optimized activated catalysts 1–4 (5.0 mol %) were added in the reaction mixture of benzaldehyde (1.0 mmol) and malononitrile (1.1 mmol) and the resulting mixture was stirred at rt for a different time scale depending upon progress of the reaction monitored by thin layer chromatography (TLC). Information on the product formation was analyzed using 1H and 13C NMR and FT-IR techniques (Figures S42–S46). Upon reaction completion, the mixture was diluted with 5 mL of CH3OH to dissolve the organic products which was followed by centrifugation cum filtration and the supernatant liquid was evaporated to dryness. The pure product was obtained by recrystallization in MeOH. The catalyst was removed by filtration and washed with EtOAc which was recovered, dried, and reused as required (Scheme 4). 2-Benzylidenemalononitrile (Table 2, entry 1) mp: 83.5 °C; 1H NMR (500 MHz, CDCl3; δ, ppm): 7.89 (d, J = 8.0 Hz, 2H), 7.78 (s, 1H), 7.63 (t, J = 7.5 Hz, 1H), 7.54 (t, J = 7.8 Hz, 2H). 13C NMR (125 MHz, CDCl3; δ, ppm): 160.03, 134.76, 131.01, 130.83, 129.68, 113.83, 112.67, 82.93. FT-IR (KBr, cm–1): 3426, 3033, 2956, 2867, 2777, 1695, 1668, 1592, 1569, 1491, 1461, 1375, 1336, 1300, 1231, 1202, 1182, 1163, 1144, 1101, 1001, 972, 776, 756.
2.7.3. Optimization of the Catalyst and Solvent for the Knoevenagel Condensation Reaction
The objective of these optimizations was to develop economical and most effective catalyst and solvent system for the Knoevenagel reaction. To seek for the possibility of heterogeneous catalytic behavior of 1–4, the one-pot Knoevenagel reaction was carried out in different optimized solvents. At the onset, catalysts 1–4 were separately employed in different sets of the model Knoevenagel reaction using benzaldehyde and malononitrile reactants to yield 2-benzylidenemalononitrile at rt under solvent-free conditions. The reaction process can be constantly monitored by TLC, illustrating that this catalytic reaction indicated a significant amount of product after 25 min. Taking a random amount of catalysts for the fixed timescale of 25 min, 1–4 provided the product yields 61, 68, 59, and 53%, respectively. Notably, the said reaction completes in 4 h under catalyst-free conditions. To select the most appropriate reaction condition, the parameters such as catalyst amount and best solvent were optimized (Tables S1–S4). The performance of 1–4 was examined by varying the catalytic amount to 1, 2, 3, 4, 5, and 10 mol % in the reaction and observed that increasing the catalytic loading from 1 to 5 mol % leads to the enhanced yield of the product; however, escalating the amount from 5 to 10 mol % could not significantly increase the product yield at the same time scale. The kinetics of conversion profiles show that the initial reaction rates and the final product yield were higher with 5 mol % relative to the other catalytic loadings; hence, the best catalytic loading of 1–4 chosen was 5 mol % (Figure S47, Tables S1–S4, entry 6). In addition, the reaction was investigated with various solvents, that is, H2O, EtOH, CH2Cl2, CH3CN, toluene, and benzene, and also under solvent-free conditions wherein moderate yields were observed using these solvents (Tables S1–S4, entries 8–14), whereas solvent-free conditions afforded excellent yields of the product in the 25 min time scale. The lower yields in H2O and EtOH relative to that of the solvent-free reaction may be attributed to the solvation of the active functional groups by these solvents as well as due to hydrogen-bonding interaction between active protonic sites of 1–4, thereby diminishing in the catalytic efficiency. Therefore, 5 mol % catalytic loading of 1–4 under the solvent-free conditions at rt was designated as the optimum condition (Tables S1–S4).
Among the tested solvents, ethanol has been observed as the best solvent for the Knovenegal reaction; hence, further experiments for the optimization of catalyst loading were performed in ethanol. A blank-controlled experiment afforded 38% conversion of benzaldehyde after 4 h in ethanol at rt, whereas 95–98% conversion could be accomplished using catalysts 1–4 under the same conditions and 25 min time scale (Figures S52 and S53). The time-conversion plot exhibiting the comparative reaction rate in the presence and absence of 1–4 clearly suggests that the reaction is promoted only in the presence of catalysts (Figure S53). Furthermore, leaching experiments have also been conducted under identical conditions to assure whether the reaction is stimulated by the heterogeneous catalysts not due to the active sites leached into the solution. Therefore, the reaction between benzaldehyde and malononitrile was initiated in the presence of 1–4 under identical conditions and the solid catalyst was removed by filtration after 10 min while the resulting solution was allowed to continue up to 25 min (Figure S55). Notably, the reaction rate was significantly reduced in the absence of a catalyst which indicates that the reaction is exclusively catalyzed by 1–4. Comparison of the reaction rates for 1–4 clearly indicates a higher initial reaction rate for 2 relative to those of 1, 3, and 4 which may be attributed to either the lack of diffusion restrictions or possibility of increasing coordination number for the Cd(II) center. Furthermore, recovered catalysts have also been analyzed by PXRD which revealed the structural and morphological stability of 1–4 (Figure Figure88).
PXRD patterns of 1–4 freshly prepared, recovered after the first cycle, and recycled after seven (1–3) and five (4) cycles.
Hence, the stability of 1–4 was examined by recycling the catalyst in the successive runs up to seven cycles and observed consistent performance for 1–3; however, 4 displayed consistent performance up to five cycles only (Figure S50). Relatively lower reusability observed for 4 may be attributed to the presence of K(I) centers along with Cu(II) centers in the framework. Moreover, the stability of these catalysts during the reusability experiments was also ascertained by comparing the PXRD pattern of the fresh with those of recovered catalysts up to the respective consistent performance (Figure Figure88). The catalytic efficiency of a heterogeneous catalyst with respect to the previously reported catalysts can be best assessed through calculation of turnover number or turnover frequency; therefore, 1–4 have been exhaustively compared with earlier reports. However, the yield achieved in the presence of 1–4 at rt is preferable over the catalysts which operate either at 60–130 °C or involve large time scale reactions (12–24 h).23a High yield (98%), ambient temperature (rt), and shorter time (4 h) along with catalyst stability up to many cycles demonstrate the improvement of catalysts 1–4 relative to the earlier reports (Table S11).23b,62 The salient features of 1–4 comprise high performance in the Knovenagel reaction under solvent-free conditions, functioning under mild reaction conditions, short reaction time, wide substrate scope, and high stability.
2.7.4. Plausible Reaction Mechanism
CPs can act as Lewis bases or acids in the catalytic medium depending on the nature of the ligands and metal ions as well as the coordination environment. In 1–4, metal centers Zn(II)/Cd(II)/Co(II)/Cu(II) impart Lewis acidic sites and the carboxylate group present in the 2,3-pdca linker can act as a weak Bronsted base. Thus, 1–4 can be considered as a potential acid–base catalyst for the Knoevenagel condensation reaction in which acidic and basic sites can synergistically catalyze the reaction to improve its efficiency. As observed in the SC-XRD data, the offset packing of the networks in 1–3 perhaps blocks the channels supporting the nonporous nature and hence, the condensation reaction may be occurring on the catalyst surface. On the basis of crystal structure and based on the previous reports,75,167 a plausible mechanism for the Knoevenagel reaction on the Lewis acidic site has been illustrated (Scheme 5). The reaction is plausibly initiated by the attack of the polarized carbonyl oxygen from the aldehyde with the metal center of the respective CP, followed by subsequent opening of the weakly coordinated chelating carboxylate oxygen from the Lewis acid site. Simultaneously, detachment of an acidic proton of the methylene group of the malononitrile produces a carbonium anion. In the next step, the carbonium anion reacts with the carbonyl group of benzaldehyde to give an intermediate which undergoes rearrangement and elimination of water to afford the final product.
2.7.5. Recyclability of Catalysts 1–4
Catalysts 1–4 might have provided lodgings for activated guests in their channels, consequently, the prominent Knoevenagel condensation reaction was selectively stimulated to afford the product in good yield. To examine the recyclability of 1–4 upon reaction completion, the solid catalysts were collected and separated dissolving the reaction mixture in ethanol followed by filtering and drying to reuse for another set of the same reaction. After filtration and drying, the catalysts were subjected to a vacuum oven at 80 °C for 4–6 h to remove adsorbed guests. The vacuum-dried catalyst was then reused for the next cycle of the same reaction. This experiment was repeated seven times and found that 1–3 perform quite well, whereas 4 starts decreasing in its catalytic activity after five catalytic cycles (Figure Figure88). The deactivation of the catalysts after the seventh and fifth cycle may be attributed to the pore blocking by the generated product.178,179 Remarkably, PXRD patterns of the recycled CPs 1–4 after the seventh and fifth runs, respectively, exhibited peak profiles similar to those of the fresh compounds (Figure Figure88). Relative performances of 1–4 with some previously reported catalysts for the Knoevenagel condensation suggested that our catalysts are comparative in terms of cost-effectiveness, ambient temperature, and short time scale of the reaction (Tables S11 and 3).33,88,168,180,181
Table 3
| entry | catalyst (mol %) | optimized catalyst quantity | time (m) | yield (%) |
|---|---|---|---|---|
| 1 | [Zn(pdca)·(H2O)2] | 5 mol % | 5 | 47 |
| 10 | 67 | |||
| 15 | 82 | |||
| 20 | 92 | |||
| 25 | 97 | |||
| 2 | [Cd(pdca)·(H2O)2] | 5 mol % | 5 | 59 |
| 10 | 83 | |||
| 15 | 92 | |||
| 20 | 95 | |||
| 25 | 98 | |||
| 3 | [Co(pdca)·(H2O)2] | 5 mol % | 5 | 53 |
| 10 | 69 | |||
| 15 | 83 | |||
| 20 | 93 | |||
| 25 | 96 | |||
| 4 | [(CH3)2NH2][CuK(pdca)(PA)(NO3)2] | 5 mol % | 5 | 51 |
| 10 | 74 | |||
| 15 | 85 | |||
| 20 | 92 | |||
| 25 | 95 |
2.7.6. Hot-Filtration Experiments
To confirm the heterogeneous nature of the catalysts, hot-filtration experiments were also performed.169−174 In this context, the solid catalysts 1–4 were removed from a hot solution by filtration for 10 min after initiating the catalytic run. The reaction of the filtrate was then monitored for another 15 min wherein insignificant catalytic conversion was observed (Figure S55). It indicates almost no leaching of metal from the catalyst and thus the heterogeneous nature of the catalysts. The filtrate was also analyzed by atomic absorption spectroscopy (AAS), which indicated a very low concentration of free metal(II) ions (0.000017–0.000079%) from catalysts 1–4 that leached out into the reaction solution (Table S9).175−177
2.7.7. Synthesis of Benzoic Anhydrides via Aldehydic C–H Activation Using Catalysts 1–4
To a solution of benzaldehyde (1.0 mmol) and catalyst 1/2/3/4 (5 mol %) in CH3CN (2 mL), a 70% solution of TBHP (1.5 equiv) in CH3CN was added gradually over 10 min under stirring. Furthermore, the reaction temperature was increased to 70 °C followed by stirring for another 1 h under a N2 atmosphere and the progress of the reaction was monitored by TLC (Scheme 6). After reaction completion, the solvent was evaporated under reduced pressure and the residue was purified using silica gel column chromatography (hexane/EtOAc, 4.5:0.5). Benzoic anhydride: Colorless crystalline powder; yield: 98%; Anal. Calcd for C14H10O3 (226.23): C, 74.33; H, 4.46; N, 0.0. Found: C, 74.36; H, 4.48, N, 0.0. Rf = 0.5797, 1H NMR (500 MHz, CDCl3): δ 8.13 (d, J = 7.5 Hz, 2H), 7.63 (t, J = 7.5 Hz, 1H), 7.50 (t, J = 7.8 Hz, 2H). 13C NMR (125 MHz, CDCl3): δ 162.48, 134.66, 130.67, 128.99, 128.59. IR (KBr, cm–1): ν = 3438, 3065, 3036, 3011, 1789, 1725, 1686, 1650, 1599, 1493, 1452, 1345, 1314, 1279, 1173, 1098, 1076, 1049, 996, 870, 801, 778, 702.
To employ 1–4 as heterogeneous catalysts for the production of benzoic anhydrides via C–H bond activation, the best reaction conditions and various other parameters such as solvent, oxidant, amount of catalyst, and reaction time were optimized.182,183
2.7.8. Optimizations for C–H Bond Activation Reactions in the Presence of 1–4
The effect of various solvents such as CH2Cl2, ClCH2CH2Cl, chloroform, ethanol, water, diethyl ether, THF, DMF, and CH3CN was investigated independently for the C–H activation of benzaldehyde in the presence of the catalyst and TBHP, as a model reaction (Table 2). There are definite evidences on solvent-dependent C–H bond activation of benzaldehyde. The results of the present study revealed the maximum yield obtained using a CH3CN solvent; therefore, it was chosen as an ideal solvent for this reaction (Tables 1 and 4).
Table 4
| entry | solvent/medium of the reaction | temp (°C) | conversion (%) | selectivity (%) |
|---|---|---|---|---|
| 1 | CH3OH | 18 | 45 | |
| 2 | C2H5OH | 19 | 48 | |
| 3 | CH2Cl2 | trace | 52 | |
| 4 | C2H4Cl2 | 5 | 58 | |
| 4 | DMF | 23 | 64 | |
| 5 | THF | 12 | 72 | |
| 6 | H2O | 24 | 78 | |
| 7 | benzene | rt | 29 | 35 |
| 8 | toluene | 35 | 93 | |
| 9 | diethyl ether | 70 | 96 | |
| 10 | CH3CN | 89 | 98 |
2.7.9. Optimization of the Oxidant
Among oxidants such as air, TBHP, H2O2, and oxone, TBHP was optimized as the best oxidant for the abovementioned reaction (Table 5, entry 7). It is worth mentioning that using H2O2 as an oxidant leads to the conversion of a large part of aldehyde to carboxylic acid and the negligible desired product was observed.
Table 5
| entry | oxidant used for desired product | % age yield |
|---|---|---|
| 1 | air/oxygen | N.O. |
| 2 | CHP | N.O. |
| 3 | oxone | N.O. |
| 4 | K2S2O8 | N.O. |
| 5 | H2O2 | 16 |
| 6 | TEMPO | N.O. |
| 7 | TBHP | 83 |
2.7.10. Effect of the Catalyst Quantity
The amount of the catalysts 1–4 was optimized in CH3CN in the presence of TBHP as an oxidant. The best results obtained using 5 mol % of catalysts, whereas the exceeding catalytic quantity does not show any noticeable enhancement in the product yield (Table 6).
Table 6
| entry | catalyst | amount of catalyst (mol %) | (%) yield |
|---|---|---|---|
| 1.1 | 1 | 1 | 43 |
| 1.2 | 2 | 54 | |
| 1.3 | 3 | 65 | |
| 1.4 | 4 | 73 | |
| 1.5 | 5 | 97 | |
| 1.6 | 10 | 97 | |
| 2.1 | 2 | 1 | 58 |
| 2.2 | 2 | 69 | |
| 2.3 | 3 | 77 | |
| 2.4 | 4 | 84 | |
| 2.5 | 5 | 98 | |
| 2.6 | 10 | 98 | |
| 3.1 | 3 | 1 | 39 |
| 3.2 | 2 | 46 | |
| 3.3 | 3 | 52 | |
| 3.4 | 4 | 78 | |
| 3.5 | 5 | 96 | |
| 3.6 | 10 | 96 | |
| 4.1 | 4 | 1 | 61 |
| 4.2 | 2 | 69 | |
| 4.3 | 3 | 73 | |
| 4.4 | 4 | 76 | |
| 4.5 | 5 | 95 | |
| 4.6 | 10 | 96 |
After optimization of the model reaction, generality of the reaction was examined using benzaldehyde with both electron-rich and electron-poor substituents and the results showed high catalyst proficiency for C–H bond activation cum formation of anhydrides. Reportedly, the aldehydes with a NO2 substituent at para- or ortho-positions in the presence of CuO nanoparticles resulted in the NO-product formation.27 Other literature reports illustrate the reaction of benzaldehyde in the presence of CuO, CuCl, Cu-MOFs, CuCl2, and TBHP which yielded 35–75% of the anhydrides, after 3 h63,184 (Table S12, entries 6–8 and 10). Notably, in the presence of 1–4, aldehydes having electron-withdrawing groups lead to the formation of the corresponding anhydrides in relatively good yields, whereas aldehydes with electron-donating groups were converted to the respective anhydrides with good-to-excellent yields (Table S12 entry 13–16). After reaction completion, the catalysts were feasibly separated by filtration and recycled several times. On the other hand, utmost of the reported methods used an equivalent amount of reagents which are expensive and environmentally alarming (Table S12, entry 1–5).
2.7.11. Catalyst Recycling of 1–4
Reusability with consistent performance is one of the important concerns in heterogeneous catalysts. Notably, 1–4 could be recovered simply by filtration, washing with methanol, and drying under a vacuum oven @ 80 °C for 4–6 h and these recovered 1–4 were used for the same C–H bond activation reaction up to four cycles. However, the results indicate that 1–4 can be used for several cycles with minimal loss of activity which is also evident from unchanged HRTEM structural morphology even after seven catalytic cycles (Figure S58). The HRTEM images strongly suggested preserved crystallinity as well as morphology even after seven catalytic cycles of 1–3 and five catalytic cycles of 4. Likewise, no framework degradation of the hydrolysis reaction63 could be significantly observed in the PXRD patterns (Table 7).
Table 7
| entry | catalyst | time (min) | yield (%) |
|---|---|---|---|
| 1 | [Zn(pdca)·(H2O)2] | 2 | 38 |
| 5 | 56 | ||
| 10 | 77 | ||
| 15 | 89 | ||
| 20 | 97 | ||
| 2 | [Cd(pdca)·(H2O)2] | 2 | 42 |
| 5 | 61 | ||
| 10 | 87 | ||
| 15 | 94 | ||
| 20 | 99 | ||
| 3 | [Co(pdca)·(H2O)2] | 2 | 36 |
| 5 | 51 | ||
| 10 | 68 | ||
| 15 | 92 | ||
| 20 | 97 | ||
| 4 | [(CH3)2NH2][CuK(pdca)(PA)(NO3)2] | 2 | 41 |
| 5 | 53 | ||
| 10 | 71 | ||
| 15 | 93 | ||
| 20 | 98.5 |
2.7.12. Hot-Filtration Test
Furthermore, leaching of metal ions from the heterogeneous surface of catalysts 1–4 was examined through the hot-filtration test. Hence, the reaction was initiated under the optimized reaction conditions and the reaction mixture was filtered off to separate the solid catalysts after 5 min under hot conditions. The filtrate in the absence of solid was continued up to 20 min (Table S10). The analysis of the reaction mixture indicated that the yield of the reaction was insignificantly improved (Figure S56). It strongly indicated the heterogeneous nature of the catalysts 1–4. Moreover, the filtrates were also analyzed by AAS which exhibited a complete absence of free metal(II) ions (0.000000–0.000000) indicating no leaching from catalysts 1–4 (Table S10).
It is noteworthy to mention that the catalytic performance for the Knoevenagel condensation reaction follows the order of 2 > 1 > 3 > 4. The literature reveals that many factors including the particle size, shape, chemical composition, metal–support interaction, and metal–reactant/solvent interaction can have significant influences on the catalytic properties of the catalysts. It is worth stating that since all the catalysts comprise the same pdca2– ligand and 1–3 are isostructural, the difference in product yield is small (95–99%) which may be attributable to the feasibility of basic sites, ionic-covalent nature of the metal–oxygen bonds, ready production of “Mn+–O2 Lewis acid–base” pair, and so forth. All the metal centers [Zn(II), Cd(II), and Co(II)] are six-coordinated and possess entirely the same coordination environment by pdca2– and aqua ligands; therefore, small variation in catalytic performance may be attributed to the size of the metal ions and their electronic configuration. The ionic radii order for these metal ions follows order Cd(II) > Zn(II) > Co(II) which is analogous to their catalytic performances. Therefore, better catalytic performance of 2 over 1, 3, and 4 may be ascribed to the larger size of Cd(II) and its possibility to extend coordination no up to 7-, 8-, and 9-coordination. On the other hand, the catalytic efficiency order follows 2 > 4 > 1 > 3 for the C–H activation reaction which may be attributed to the rms roughness (Rq) which has been calculated to be 0.332, 2.71, 0.328, and 2.17 nm for 1–4, respectively. In addition, five-coordinated Cu(II) in 4 may offer a better binding site for the substrate over six-coordinated metal centers in 1–3. Moreover, the catalytic activities of 1–4 may be ascribed to the combined effect of the metal atom involved in the respective CP and/or porosity of the framework. The CPs 1–4 contain both Lewis acid (Zn, Cd, Co, and Cu center) and Lewis basic (carboxylate and free pyridyl groups) sites, which makes them suitable for bifunctional catalysis.
3. Experimental Section
3.1. Chemicals and Reagents
All the chemicals including Zn(NO3)2·6H2O, Cd(NO3)2·4H2O, Co(NO3)2·6H2O, Cu(NO3)2·3H2O ≥ 99.00%, and potassium hydroxide (KOH) were procured from HiMedia Chemicals Pvt. Ltd., India. Rare chemical pyridine-2,3-dicarboxylic acid or quinolinic acid was purchased from Sigma-Aldrich Pvt. Ltd., USA. All the solvents such as ethanol and distilled water were purchased from Merck Life Science Pvt Ltd (India). The reagents were procured from commercial sources and used as received. The chemicals and reagents were pure, whereas the solvents were dried and distilled following standard literature procedures.123
4. Conclusions
Four CPs [M(pdca)·(H2O)2] [M = Zn(II), Cd(II), Co(II)] (1–3), and [(CH3)2NH2][CuK(pdca)(pa)(NO3)2] (4) have been synthesized implementing a solvothermal reaction strategy. CPs 1–4 have been thoroughly characterized using various spectral techniques, that is, elemental analyses and thermal and spectral techniques. Moreover, the structural information on 1–4 have been obtained by PXRD and X-ray single-crystal analyses, whereas morphological insights were acquired by FESEM, AFM, EDX, and HRTEM analyses and BET surface area analysis. The roughness parameter was calculated from AFM, whereas HRTEM aided in defining the dimensions of small domains and in measuring the interplanar spacing in the CPs. The structurally similar 1–3 are 1D coordination frameworks, whereas 4 is a 3D network. In addition, all 1–4 display good luminescence at rt. Furthermore, feasibly prepared 1–4 serve as efficient and economic porous heterogeneous catalysts for the Knoevenagel condensation and C–H bond activation reaction under mild conditions. Using catalysts 1–4 in Knoevenagel condensation and in C–H activation reaction leads to the product yields in the range of 95–98 and 97–99%, respectively. Notably, catalytic performance of 1–4 was also reconnoitered through reusability and percolating experiments and observed that 1–3 can be reused up to seven cycles with almost consistent catalytic efficiency, whereas 4 retains its catalytic efficacy up to five cycles. The relative catalytic efficiency of 1–4 toward the Knoevenagel condensation reaction has been observed in the order 2 > 1 > 3 > 4, whereas the efficiency for C–H activation follows the order 2 > 4 > 1 > 3. Overall, the present result demonstrates synthetic, structural, morphological, optical, and catalytic aspects of CPs 1–4.
Acknowledgments
R.P. acknowledges the support from the Department of Science and Technology (DST), New Delhi, for providing financial assistance through DST Inspire Faculty grant (IFA12-CH-66) and D.S. acknowledges UGC for providing research fellowship for Central Universities. Authors are also thankful to the Department of Chemistry, Dr HS Gour Central University, Sagar, and Department of Chemistry, National Institute of Technology Uttarakhand, for providing necessary support in carrying out the research.
Supporting Information Available
The Supporting Information is available free of charge at https://pubs.acs.org/doi/10.1021/acsomega.1c01155.
Experimental section; details of the synthesis and characterization; packing diagram of CPs 1, 2, and 4; Crystallographic data: CCDC-2053914, 2053915, and 2053916 for 1, 2, and 4, respectively; coordination modes of the 2,3-pdca linker; structure figures; TGA curves; SEM, HRTEM, and AFM images; UV/vis and fluorescence spectra of 1–4; PXRD patterns for 1–4; CCDC reference numbers 2053914, 2053915 and 2053916 for 1, 2, and 4, respectively; and 1H and 13C NMR spectra of the products 2-benzylidenemalononitrile and benzoic anhydride (PDF)
Crystallographic information files (CIF)
References
- Qiu Q.; Chen H.; Wang Y.; Ying Y. Recent Advances in the Rational Synthesis and Sensing Applications of Metal-Organic Framework Biocomposites. Coord. Chem. Rev. 2019, 387, 60–78. 10.1016/j.ccr.2019.02.009. [CrossRef] [Google Scholar]
- Zheng C.; Greer H. F.; Chiang C.-Y.; Zhou W. Microstructural Study of the Formation Mechanism of Metal-Organic Framework MOF-5. CrystEngComm 2014, 16, 1064–1070. 10.1039/c3ce41291a. [CrossRef] [Google Scholar]
- O’Keeffe M.; Yaghi O. M. Deconstructing the Crystal Structures of Metal–Organic Frameworks and Related Materials into Their Underlying Nets. Chem. Rev. 2012, 112, 675–702. 10.1021/cr200205j. [Abstract] [CrossRef] [Google Scholar]
- Li H.; Eddaoudi M.; O’Keeffe M.; Yaghi O. M. Design and Synthesis of an Exceptionally Stable and Highly Porous Metal- Organic Framework. Nature 1999, 402, 276–279. 10.1038/46248. [CrossRef] [Google Scholar]
- Yaghi O. M.; O’Keeffe M.; Ockwig N. W.; Chae H. K.; Eddaoudi M.; Kim J. Reticular Synthesis and the Design of New Materials. Nature 2003, 423, 705–714. 10.1038/nature01650. [Abstract] [CrossRef] [Google Scholar]
- Yaghi O. M.; O’Keeffe M.; Kanatzidis M. Design of Solids from Molecular Building Blocks: Golden Opportunities for Solid State Chemistry. J. Solid State Chem. 2000, 152, 1–2. 10.1006/jssc.2000.8733. [CrossRef] [Google Scholar]
- Bigdeli F.; Lollar C. T.; Morsali A.; Zhou H. C. Switching in Metal–Organic Frameworks. Angew. Chem., Int. Ed. 2020, 59, 4652–4669. 10.1002/anie.201900666. [Abstract] [CrossRef] [Google Scholar]
- He Z.; Zhao X.; Pan X.; Li Y.; Wang X.; Xu H.; Xu Z. Ligand Geometry Controlling Zn-MOF Partial Structures for Their Catalytic Performance in Knoevenagel Condensation. RSC Adv. 2019, 9, 25170–25176. 10.1039/c9ra04499j. [CrossRef] [Google Scholar]
- Khandelwal G.; Maria Joseph Raj N. P.; Kim S. J. Zeolitic Imidazole Framework: Metal–Organic Framework Subfamily Members for Triboelectric Nanogenerators. Adv. Funct. Mater. 2020, 30, 1910162.10.1002/adfm.201910162. [CrossRef] [Google Scholar]
- Han Y.-H.; Zhou Z.-Y.; Tian C.-B.; Du S.-W. A Dual-Walled Cage MOF as an Efficient Heterogeneous Catalyst for the Conversion of CO2 under Mild and Co-Catalyst Free Conditions. Green Chem. 2016, 18, 4086–4091. 10.1039/c6gc00413j. [CrossRef] [Google Scholar]
- Li X.; Wang B.; Cao Y.; Zhao S.; Wang H.; Feng X.; Zhou J.; Ma X. Water Contaminant Elimination Based on Metal–Organic Frameworks and Perspective on Their Industrial Applications. ACS Sustainable Chem. Eng. 2019, 7, 4548–4563. 10.1021/acssuschemeng.8b05751. [CrossRef] [Google Scholar]
- Chen Z.; Hanna S. L.; Redfern L. R.; Alezi D.; Islamoglu T.; Farha O. K. Reticular Chemistry in the Rational Synthesis of Functional Zirconium Cluster-Based MOFs. Coord. Chem. Rev. 2019, 386, 32–49. 10.1016/j.ccr.2019.01.017. [CrossRef] [Google Scholar]
- Baumann A. E.; Burns D. A.; Liu B.; Thoi V. S. Metal-Organic Framework Functionalization and Design Strategies for Advanced Electrochemical Energy Storage Devices. Commun. Chem. 2019, 2, 86.10.1038/s42004-019-0184-6. [CrossRef] [Google Scholar]
- Fu H.-R.; Wang F.; Zhang J. A Stable Zinc-4-Carboxypyrazole Framework with High Uptake and Selectivity of Light Hydrocarbons. Dalton Trans. 2015, 44, 2893–2896. 10.1039/c4dt03594a. [Abstract] [CrossRef] [Google Scholar]
- Li J.-R.; Kuppler R. J.; Zhou H.-C. Selective Gas Adsorption and Separation in Metal–Organic Frameworks. Chem. Soc. Rev. 2009, 38, 1477–1504. 10.1039/b802426j. [Abstract] [CrossRef] [Google Scholar]
- Bao Z.; Chang G.; Xing H.; Krishna R.; Ren Q.; Chen B. Potential of Microporous Metal-Organic Frameworks for Separation of Hydrocarbon Mixtures. Energy Environ. Sci. 2016, 9, 3612–3641. 10.1039/c6ee01886f. [CrossRef] [Google Scholar]
- Pal A.; Chand S.; Boquera J. C.; Lloret F.; Lin J.-B.; Pal S. C.; Das M. C. Three Co(II) Metal-Organic Frameworks with Diverse Architectures for Selective Gas Sorption and Magnetic Studies. Inorg. Chem. 2019, 58, 6246–6256. 10.1021/acs.inorgchem.9b00471. [Abstract] [CrossRef] [Google Scholar]
- Li H.-Y.; Wei Y.-L.; Dong X.-Y.; Zang S.-Q.; Mak T. C. W. Novel Tb-MOF Embedded with Viologen Species for Multi-Photofunctionality: Photochromism, Photomodulated Fluorescence, and Luminescent PH Sensing. Chem. Mater. 2015, 27, 1327–1331. 10.1021/cm504350q. [CrossRef] [Google Scholar]
- Pal S.; Bharadwaj P. K. A Luminescent Terbium MOF Containing Hydroxyl Groups Exhibits Selective Sensing of Nitroaromatic Compounds and Fe(III) Ions. Cryst. Growth Des. 2016, 16, 5852–5858. 10.1021/acs.cgd.6b00930. [CrossRef] [Google Scholar]
- Hou B.-L.; Tian D.; Liu J.; Dong L.-Z.; Li S.-L.; Li D.-S.; Lan Y.-Q. A Water-Stable Metal-Organic Framework for Highly Sensitive and Selective Sensing of Fe3+ Ion. Inorg. Chem. 2016, 55, 10580–10586. 10.1021/acs.inorgchem.6b01809. [Abstract] [CrossRef] [Google Scholar]
- Li H.-Y.; Xu H.; Zang S.-Q.; Mak T. C. W. A Viologen-Functionalized Chiral Eu-MOF as a Platform for Multifunctional Switchable Material. Chem. Commun. 2016, 52, 525–528. 10.1039/c5cc08168h. [Abstract] [CrossRef] [Google Scholar]
- Stavila V.; Talin A. A.; Allendorf M. D. MOF-Based Electronic and Opto-Electronic Devices. Chem. Soc. Rev. 2014, 43, 5994–6010. 10.1039/c4cs00096j. [Abstract] [CrossRef] [Google Scholar]
- a. Dolgopolova E. A.; Shustova N. B.
Metal-Organic Framework
Photophysics: Optoelectronic Devices, Photoswitches, Sensors, and
Photocatalysts. MRS Bull.
2016, 41, 890–896. 10.1557/mrs.2016.246. [CrossRef] [Google Scholar]
b. Liu H.; Wang Y.; Qin Z.; Liu D.; Xu H.; Dong H.; Hu W. Electrically Conductive Coordination Polymers for Electronic and Optoelectronic Device Applications. J. Phys. Chem. Lett. 2021, 12, 1612–1630. 10.1021/acs.jpclett.0c02988. [Abstract] [CrossRef] [Google Scholar] - Yang F.; Cheng S.; Zhang X.; Ren X.; Li R.; Dong H.; Hu W. Organic Optoelectronics: 2D Organic Materials for Optoelectronic Applications. Adv. Mater. 2018, 30, 1870012.10.1002/adma.201870012. [Abstract] [CrossRef] [Google Scholar]
- Li P.; Guo M.-Y.; Yin X.-M.; Gao L. L.; Yang S.-L.; Bu R.; Gong T.; Gao E.-Q. Interpenetration-Enabled Photochromism and Fluorescence Photomodulation in a Metal–Organic Framework with the Thiazolothiazole Extended Viologen Fluorophore. Inorg. Chem. 2019, 58, 14167–14174. 10.1021/acs.inorgchem.9b02220. [Abstract] [CrossRef] [Google Scholar]
- Zhang T.; Lin W. Metal-Organic Frameworks for Artificial Photosynthesis and Photocatalysis. Chem. Soc. Rev. 2014, 43, 5982–5993. 10.1039/c4cs00103f. [Abstract] [CrossRef] [Google Scholar]
- Tan Y.-X.; He Y.-P.; Yuan D.; Zhang J. Use of Aligned Triphenylamine-Based Radicals in a Porous Framework for Promoting Photocatalysis. Appl. Catal., B 2018, 221, 664–669. 10.1016/j.apcatb.2017.09.054. [CrossRef] [Google Scholar]
- Dhakshinamoorthy A.; Opanasenko M.; Čejka J.; Garcia H. Metal Organic Frameworks as Heterogeneous Catalysts for the Production of Fine Chemicals. Catal. Sci. Technol. 2013, 3, 2509–2540. 10.1039/c3cy00350g. [CrossRef] [Google Scholar]
- Sabale S.; Zheng J.; Vemuri R. S.; Yu X.-Y.; McGrail B P.; Motkuri R. K.Recent Advances in Metal-Organic Frameworks for Heterogeneous Catalyzed Organic Transformations. Synth. Catal. 2016, 01.10.4172/2574-0431.100005. [CrossRef] [Google Scholar]
- Madasamy K.; Kumaraguru S.; Sankar V.; Mannathan S.; Kathiresan M. A Zn Based Metal Organic Framework as a Heterogeneous Catalyst for C-C Bond Formation Reactions. New J. Chem. 2019, 43, 3793–3800. 10.1039/c8nj05953e. [CrossRef] [Google Scholar]
- Zhang S.; He H.; Sun F.; Zhao N.; Du J.; Pan Q.; Zhu G. A Novel Adenine-Based Zinc(II) Metal-Organic Framework Featuring the Lewis Basic Sites for Heterogeneous Catalysis. Inorg. Chem. Commun. 2017, 79, 55–59. 10.1016/j.inoche.2016.11.011. [CrossRef] [Google Scholar]
- Zhu L.; Liu X.-Q.; Jiang H.-L.; Sun L.-B. Metal–Organic Frameworks for Heterogeneous Basic Catalysis. Chem. Rev. 2017, 117, 8129–8176. 10.1021/acs.chemrev.7b00091. [Abstract] [CrossRef] [Google Scholar]
- Xu C.; Fang R.; Luque R.; Chen L.; Li Y. Functional Metal–Organic Frameworks for Catalytic Applications. Coord. Chem. Rev. 2019, 388, 268–292. 10.1016/j.ccr.2019.03.005. [CrossRef] [Google Scholar]
- Huang C.; Zhang Y.; Yang H.; Wang D.; Mi L.; Shao Z.; Liu M.; Hou H. Oriented Controllable Fabrication of Metal-Organic Frameworks Membranes as Solid Catalysts for Cascade Indole Acylation-Nazarov Cyclization for Cyclopentenone[ b]Indoles. Cryst. Growth Des. 2018, 18, 5674–5681. 10.1021/acs.cgd.8b01050. [CrossRef] [Google Scholar]
- Li F.-L.; Shao Q.; Huang X.; Lang J.-P. Nanoscale Trimetallic Metal-Organic Frameworks Enable Efficient Oxygen Evolution Electrocatalysis. Angew. Chem. 2018, 130, 1906–1910. 10.1002/ange.201711376. [Abstract] [CrossRef] [Google Scholar]
- Xue J.-Y.; Li C.; Li F.-L.; Gu H.-W.; Braunstein P.; Lang J.-P. Recent Advances in Pristine Tri-Metallic Metal-Organic Frameworks toward the Oxygen Evolution Reaction. Nanoscale 2020, 12, 4816–4825. 10.1039/c9nr10109h. [Abstract] [CrossRef] [Google Scholar]
- Cao X.; Tan C.; Sindoro M.; Zhang H. Hybrid Micro-/Nano-Structures Derived from Metal-Organic Frameworks: Preparation and Applications in Energy Storage and Conversion. Chem. Soc. Rev. 2017, 46, 2660–2677. 10.1039/c6cs00426a. [Abstract] [CrossRef] [Google Scholar]
- Xia W.; Mahmood A.; Zou R.; Xu Q. Metal-Organic Frameworks and Their Derived Nanostructures for Electrochemical Energy Storage and Conversion. Energy Environ. Sci. 2015, 8, 1837–1866. 10.1039/c5ee00762c. [CrossRef] [Google Scholar]
- Wu H. B.; Lou X. W. Metal-Organic Frameworks and Their Derived Materials for Electrochemical Energy Storage and Conversion: Promises and Challenges. Sci. Adv. 2017, 3, eaap925210.1126/sciadv.aap9252. [Europe PMC free article] [Abstract] [CrossRef] [Google Scholar]
- Zhang L.; Liu H.; Shi W.; Cheng P. Synthesis Strategies and Potential Applications of Metal-Organic Frameworks for Electrode Materials for Rechargeable Lithium Ion Batteries. Coord. Chem. Rev. 2019, 388, 293–309. 10.1016/j.ccr.2019.02.030. [CrossRef] [Google Scholar]
- Cui Y.; Yue Y.; Qian G.; Chen B. Luminescent Functional Metal-Organic Frameworks. Chem. Rev. 2012, 112, 1126.10.1021/cr200101d. [Abstract] [CrossRef] [Google Scholar]
- Cui Y.; Chen B.; Qian G. Luminescent Properties and Applications of Metal-Organic Frameworks. Struct. Bonding 2013, 157, 27–88. 10.1007/430_2013_133. [CrossRef] [Google Scholar]
- Zhang L.; Kang Z.; Xin X.; Sun D. Metal-Organic Frameworks Based Luminescent Materials for Nitroaromatics Sensing. CrystEngComm 2016, 18, 193–206. 10.1039/C5CE01917F. [CrossRef] [Google Scholar]
- Phadungsak N.; Kielar F.; Dungkaew W.; Sukwattanasinitt M.; Zhou Y.; Chainok K. A New Luminescent Anionic Metal-Organic Framework Based on Heterometallic Zinc(II)-Barium(II) for Selective Detection of Fe3+ and Cu2+ Ions in Aqueous Solution. Acta Crystallogr., Sect. C: Struct. Chem. 2019, 75, 1372–1380. 10.1107/s2053229619011987. [Abstract] [CrossRef] [Google Scholar]
- Shen W.-J.; Zhuo Y.; Chai Y.-Q.; Yuan R. Cu-Based Metal–Organic Frameworks as a Catalyst To Construct a Ratiometric Electrochemical Aptasensor for Sensitive Lipopolysaccharide Detection. Anal. Chem. 2015, 87, 11345–11352. 10.1021/acs.analchem.5b02694. [Abstract] [CrossRef] [Google Scholar]
- Huang C.; Lu G.; Zhang Y.; Zhu K.; Cui S.; Chen W.; Wu Z.; Qiu M.; Mi L. Programmable Triboelectric Nanogenerators Dependent on the Secondary Building Units in Cadmium Coordination Polymers. Inorg. Chem. 2021, 60, 550–554. 10.1021/acs.inorgchem.0c02946. [Abstract] [CrossRef] [Google Scholar]
- Santoro S.; Kozhushkov S. I.; Ackermann L.; Vaccaro L. Heterogeneous Catalytic Approaches in C-H Activation Reactions. Green Chem. 2016, 18, 3471–3493. 10.1039/c6gc00385k. [CrossRef] [Google Scholar]
- Gao W. Y.; Wu H.; Leng K.; Sun Y.; Ma S. Inserting CO 2 into Aryl C–H Bonds of Metal-Organic Frameworks: CO2 Utilization for Direct Heterogeneous C–H Activation. Angew. Chem., Int. Ed. 2016, 55, 5472–5476. 10.1002/anie.201511484. [Abstract] [CrossRef] [Google Scholar]
- Pascanu V.; Carson F.; Solano M. V.; Su J.; Zou X.; Johansson M. J.; Martín-Matute B. Selective Heterogeneous C–H Activation/Halogenation Reactions Catalyzed by Pd@MOF Nanocomposites. Chem.—Eur. J. 2016, 22, 3729–3737. 10.1002/chem.201502918. [Abstract] [CrossRef] [Google Scholar]
- Olivos-Suarez A. I.; Szécsényi À.; Hensen E. J. M.; Ruiz-Martinez J.; Pidko E. A.; Gascon J. Strategies for the Direct Catalytic Valorization of Methane Using Heterogeneous Catalysis: Challenges and Opportunities. ACS Catal. 2016, 6, 2965–2981. 10.1021/acscatal.6b00428. [CrossRef] [Google Scholar]
- Bai C.; Yao X.; Li Y. Easy Access to Amides through Aldehydic C-H Bond Functionalization Catalyzed by Heterogeneous Co-Based Catalysts. ACS Catal. 2015, 5, 884–891. 10.1021/cs501822r. [CrossRef] [Google Scholar]
- Karmakar A.; Pombeiro A. J. L. Recent Advances in Amide Functionalized Metal Organic Frameworks for Heterogeneous Catalytic Applications. Coord. Chem. Rev. 2019, 395, 86–129. 10.1016/j.ccr.2019.05.022. [CrossRef] [Google Scholar]
- Karmakar A.; Paul A.; Rúbio G. M. D. M.; Soliman M. M. A.; Guedes da Silva M. F. C.; Pombeiro A. J. L. Highly Efficient Bifunctional Amide Functionalized Zn and Cd Metal Organic Frameworks for One-Pot Cascade Deacetalization–Knoevenagel Reactions. Front. Chem. 2019, 7, 699.10.3389/fchem.2019.00699. [Europe PMC free article] [Abstract] [CrossRef] [Google Scholar]
- Dincǎ M.; Long J. R. Introduction: Porous Framework Chemistry. Chem. Rev. 2020, 120, 8037–8038. 10.1021/acs.chemrev.0c00836. [Abstract] [CrossRef] [Google Scholar]
- Wang J.; Han Y.; Xu H.; Xu Z. L. Microporous Assembly and Shape Control of a New Zn Metal–Organic Framework: Morphology-Dependent Catalytic Performance. Appl. Organomet. Chem. 2018, 32, e409710.1002/aoc.4097. [CrossRef] [Google Scholar]
- Zhang Y.; Yang X.; Zhou H.-C. Synthesis of MOFs for Heterogeneous Catalysis via Linker Design. Polyhedron 2018, 154, 189–201. 10.1016/j.poly.2018.07.021. [CrossRef] [Google Scholar]
- Reddy K. R.; Rajgopal K.; Maheswari C. U.; Lakshmi Kantam M. Chitosan Hydrogel: A Green and Recyclable Biopolymer Catalyst for Aldol and Knoevenagel Reactions. New J. Chem. 2006, 30, 1549–1552. 10.1039/b610355c. [CrossRef] [Google Scholar]
- Dong H.; Liu J.; Ma L.; Ouyang L. Chitosan Aerogel Catalyzed Asymmetric Aldol Reaction in Water: Highly Enantioselective Construction of 3-Substituted-3-Hydroxy-2-Oxindoles. Catalysts 2016, 6, 186.10.3390/catal6120186. [CrossRef] [Google Scholar]
- Kühbeck D.; Saidulu G.; Reddy K. R.; Díaz D. D. Critical Assessment of the Efficiency of Chitosan Biohydrogel Beads as Recyclable and Heterogeneous Organocatalyst for C-C Bond Formation. Green Chem. 2012, 14, 378–392. 10.1039/c1gc15925a. [CrossRef] [Google Scholar]
- Zhu C.; Tang H.; Yang K.; Wu X.; Luo Y.; Wang J.; Li Y. A Urea-Containing Metal-Organic Framework as a Multifunctional Heterogeneous Hydrogen Bond-Donating Catalyst. Catal. Commun. 2020, 135, 105837.10.1016/j.catcom.2019.105837. [CrossRef] [Google Scholar]
- Ugale B.; Dhankhar S. S.; Nagaraja C. M. Construction of 3D Homochiral Metal-Organic Frameworks (MOFs) of Cd(II): Selective CO2 Adsorption and Catalytic Properties for the Knoevenagel and Henry Reaction. Inorg. Chem. Front. 2017, 4, 348–359. 10.1039/c6qi00506c. [CrossRef] [Google Scholar]
- Sahu P. K.; Sahu P. K.; Gupta S. K.; Agarwal D. D. Chitosan: An Efficient, Reusable, and Biodegradable Catalyst for Green Synthesis of Heterocycles. Ind. Eng. Chem. Res. 2014, 53, 2085–2091. 10.1021/ie402037d. [CrossRef] [Google Scholar]
- Ahmadzadeh Z.; Mokhtari J.; Rouhani M. Cu-MOF: An Efficient Heterogeneous Catalyst for the Synthesis of Symmetric Anhydrides: Via the C-H Bond Activation of Aldehydes. RSC Adv. 2018, 8, 24203–24208. 10.1039/c8ra03870h. [CrossRef] [Google Scholar]
- Phan N. T. S.; Le K. K. A.; Phan T. D. MOF-5 as an Efficient Heterogeneous Catalyst for Friedel-Crafts Alkylation Reactions. Appl. Catal., A 2010, 382, 246–253. 10.1016/j.apcata.2010.04.053. [CrossRef] [Google Scholar]
- Zhang Y.; Huang C.; Mi L. Metal-Organic Frameworks as Acid- and/or Base-Functionalized Catalysts for Tandem Reactions. Dalton Trans. 2020, 49, 14723–14730. 10.1039/d0dt03025b. [Abstract] [CrossRef] [Google Scholar]
- Sakthivel B.; Dhakshinamoorthy A. Chitosan as a Reusable Solid Base Catalyst for Knoevenagel Condensation Reaction. J. Colloid Interface Sci. 2017, 485, 75–80. 10.1016/j.jcis.2016.09.020. [Abstract] [CrossRef] [Google Scholar]
- Rani D.; Singla P.; Agarwal J. “Chitosan in Water” as an Eco-Friendly and Efficient Catalytic System for Knoevenagel Condensation Reaction. Carbohydr. Polym. 2018, 202, 355–364. 10.1016/j.carbpol.2018.09.008. [Abstract] [CrossRef] [Google Scholar]
- Anbu N.; Hariharan S.; Dhakshinamoorthy A. Knoevenagel-Doebner Condensation Promoted by Chitosan as a Reusable Solid Base Catalyst. Mol. Catal. 2020, 484, 110744.10.1016/j.mcat.2019.110744. [CrossRef] [Google Scholar]
- Xu Q.; Niu Y.; Wang G.; Li Y.; Zhao Y.; Singh V.; Niu J.; Wang J. Polyoxoniobates as a Superior Lewis Base Efficiently Catalyzed Knoevenagel Condensation. Mol. Catal. 2018, 453, 93–99. 10.1016/j.mcat.2018.05.002. [CrossRef] [Google Scholar]
- Jia H.; Zhao Y.; Niu P.; Lu N.; Fan B.; Li R. Amine-Functionalized MgAl LDH Nanosheets as Efficient Solid Base Catalysts for Knoevenagel Condensation. Mol. Catal. 2018, 449, 31–37. 10.1016/j.mcat.2018.02.004. [CrossRef] [Google Scholar]
- Zhu C.; Yuan G.; Chen X.; Yang Z.; Cui Y. Chiral Nanoporous Metal–Metallosalen Frameworks for Hydrolytic Kinetic Resolution of Epoxides. J. Am. Chem. Soc. 2012, 134, 8058–8061. 10.1021/ja302340b. [Abstract] [CrossRef] [Google Scholar]
- Zhu C.; Xia Q.; Chen X.; Liu Y.; Du X.; Cui Y. Chiral Metal–Organic Framework as a Platform for Cooperative Catalysis in Asymmetric Cyanosilylation of Aldehydes. ACS Catal. 2016, 6, 7590–7596. 10.1021/acscatal.6b02359. [CrossRef] [Google Scholar]
- Song F.; Wang C.; Falkowski J. M.; Ma L.; Lin W. Isoreticular Chiral Metal–Organic Frameworks for Asymmetric Alkene Epoxidation: Tuning Catalytic Activity by Controlling Framework Catenation and Varying Open Channel Sizes. J. Am. Chem. Soc. 2010, 132, 15390–15398. 10.1021/ja1069773. [Abstract] [CrossRef] [Google Scholar]
- Saravanamurugan S.; Palanichamy M.; Hartmann M.; Murugesan V. Knoevenagel Condensation over β and Y Zeolites in Liquid Phase under Solvent Free Conditions. Appl. Catal., A 2006, 298, 8–15. 10.1016/j.apcata.2005.09.014. [CrossRef] [Google Scholar]
- Wojtaszek-Gurdak A.; Calvino-Casilda V.; Grzesinska A.; Martin-Aranda R.; Ziolek M. Impact of BrØnsted Acid Sites in MWW Zeolites Modified with Cesium and Amine Species on Knoevenagel Condensation. Microporous Mesoporous Mater. 2019, 280, 288–296. 10.1016/j.micromeso.2019.02.007. [CrossRef] [Google Scholar]
- Roy P.; Das N. Synthesis of NaX Zeolite-Graphite Amine Fiber Composite Membrane: Role of Graphite Amine in Membrane Formation for H2 /CO2 Separation. Appl. Surf. Sci. 2019, 480, 934–944. 10.1016/j.apsusc.2019.03.038. [CrossRef] [Google Scholar]
- Liang J.; Liang Z.; Zou R.; Zhao Y. Heterogeneous Catalysis in Zeolites, Mesoporous Silica, and Metal-Organic Frameworks. Adv. Mater. 2017, 29, 1701139.10.1002/adma.201701139. [Abstract] [CrossRef] [Google Scholar]
- Katkar S. S.; Lande M. K.; Arbad B. R.; Rathod S. B. Indium Modified Mesoporous Zeolite AlMCM-41 as a Heterogeneous Catalyst for the Knoevenagel Condensation Reaction. Bull. Korean Chem. Soc. 2010, 31, 1301–1304. 10.5012/bkcs.2010.31.5.1301. [CrossRef] [Google Scholar]
- Shakil M. R.; Meguerdichian A. G.; Tasnim H.; Shirazi-Amin A.; Seraji M. S.; Suib S. L. Syntheses of ZnO with Different Morphologies: Catalytic Activity toward Coumarin Synthesis via the Knoevenagel Condensation Reaction. Inorg. Chem. 2019, 58, 5703–5714. 10.1021/acs.inorgchem.9b00053. [Abstract] [CrossRef] [Google Scholar]
- Bigi F.; Chesini L.; Maggi R.; Sartori G. Montmorillonite KSF as an Inorganic, Water Stable, and Reusable Catalyst for the Knoevenagel Synthesis of Coumarin-3-Carboxylic Acids. J. Org. Chem. 1999, 64, 1033–1035. 10.1021/jo981794r. [Abstract] [CrossRef] [Google Scholar]
- Ballabeni M.; Ballini R.; Bigi F.; Maggi R.; Parrini M.; Predieri G.; Sartori G. Synthesis of Symmetrical N,N’-Disubstituted Thioureas and Heterocyclic Thiones from Amines and CS2 over a ZnO/Al2O3 Composite as Heterogeneous and Reusable Catalyst. J. Org. Chem. 1999, 64, 1029–1032. 10.1021/jo981629b. [Abstract] [CrossRef] [Google Scholar]
- Yan K.; Yang D.; Wei W.; Wang F.; Shuai Y.; Li Q.; Wang H. Silver-Mediated Radical Cyclization of Alkynoates and α-Keto Acids Leading to Coumarins via Cascade Double c-c Bond Formation. J. Org. Chem. 2015, 80, 1550–1556. 10.1021/jo502474z. [Abstract] [CrossRef] [Google Scholar]
- Siddiqui Z. N.; Musthafa T. N. M.; Praveen S.; Farooq F. Zn(Proline) 2-Catalyzed Knoevenagel Condensation under Solventfree/Aqueous Conditions and Biological Evaluation of Products. Med. Chem. Res. 2011, 20, 1438–1444. 10.1007/s00044-010-9376-4. [CrossRef] [Google Scholar]
- Davies T. E.; Taylor S. H.; Graham A. E. Nanoporous Aluminosilicate-Catalyzed Telescoped Acetalization-Direct Aldol Reactions of Acetals with 1,3-Dicarbonyl Compounds. ACS Omega 2018, 3, 15482–15491. 10.1021/acsomega.8b02047. [Europe PMC free article] [Abstract] [CrossRef] [Google Scholar]
- Sharma M. K.; Singh P. P.; Bharadwaj P. K. Two-Dimensional Rhombus Grid Coordination Polymer Showing Heterogeneous Catalytic Activities. J. Mol. Catal. A: Chem. 2011, 342–343, 6–10. 10.1016/j.molcata.2011.04.016. [CrossRef] [Google Scholar]
- Almáši M.; Zeleňák V.; Opanasenko M.; Čejka J. A Novel Nickel Metal-Organic Framework with Fluorite-like Structure: Gas Adsorption Properties and Catalytic Activity in Knoevenagel Condensation. Dalton Trans. 2014, 43, 3730–3738. 10.1039/C3DT52698D. [Abstract] [CrossRef] [Google Scholar]
- Tan Y.; Fu Z.; Zhang J. A Layered Amino-Functionalized Zinc-Terephthalate Metal Organic Framework: Structure, Characterization and Catalytic Performance for Knoevenagel Condensation. Inorg. Chem. Commun. 2011, 14, 1966–1970. 10.1016/j.inoche.2011.09.022. [CrossRef] [Google Scholar]
- Zhai Z.-W.; Yang S.-H.; Lv Y.-R.; Du C.-X.; Li L.-K.; Zang S.-Q. Amino Functionalized Zn/Cd-Metal-Organic Frameworks for Selective CO2 Adsorption and Knoevenagel Condensation Reactions. Dalton Trans. 2019, 48, 4007–4014. 10.1039/c9dt00391f. [Abstract] [CrossRef] [Google Scholar]
- Li C.; Zhong D.; Huang X.; Shen G.; Li Q.; Du J.; Li Q.; Wang S.; Li J.; Dou J. Two Organic-Inorganic Hybrid Polyoxovanadates as Reusable Catalysts for Knoevenagel Condensation. New J. Chem. 2019, 43, 5813–5819. 10.1039/c8nj06460a. [CrossRef] [Google Scholar]
- Larock R. C.; Yao T.Formation of Nitriles, Carboxylic Acids, and Derivatives by Oxidation, Substitution, and Addition. Comprehensive Organic Transformations; John Wiley & Sons, 2017; pp 1–85. [Google Scholar]
- Li Y.; Xue D.; Wang C.; Liu Z.-T.; Xiao J. Carboxylic Acid Anhydrides via Pd-Catalyzed Carbonylation of Aryl Halides at Atmospheric CO Pressure. Chem. Commun. 2012, 48, 1320–1322. 10.1039/c2cc16611a. [Abstract] [CrossRef] [Google Scholar]
- Luz I.; Corma A.; Llabrés i Xamena F. X. Cu-MOFs as Active, Selective and Reusable Catalysts for Oxidative C-O Bond Coupling Reactions by Direct C-H Activation of Formamides, Aldehydes and Ethers. Catal. Sci. Technol. 2014, 4, 1829–1836. 10.1039/c4cy00032c. [CrossRef] [Google Scholar]
- Pham P. H.; Doan S. H.; Tran H. T. T.; Nguyen N. N.; Phan A. N. Q.; Le H. V.; Tu T. N.; Phan N. T. S. A New Transformation of Coumarins: Via Direct C-H Bond Activation Utilizing an Iron-Organic Framework as a Recyclable Catalyst. Catal. Sci. Technol. 2018, 8, 1267–1271. 10.1039/c7cy02139a. [CrossRef] [Google Scholar]
- Shiina I. An Effective Use of Benzoic Anhydride and Its Derivatives for the Synthesis of Carboxylic Esters and Lactones - Powerful and Convenient Mixed Anhydride Methods Promoted by Lewis Acids or Basic Catalysts. Yuki Gosei Kagaku Kyokaishi 2005, 63, 2–17. 10.5059/yukigoseikyokaishi.63.2. [Abstract] [CrossRef] [Google Scholar]
- Mukaiyama T.; Izumi J.; Miyashita M.; Shiina I. Facile Synthesis of Lactones from Silyl ω-Siloxycarboxylates Using p -Trifluoromethylbenzoic Anhydride and a Catalytic Amount of Active Lewis Acid. Chem. Lett. 1993, 22, 907–910. 10.1246/cl.1993.907. [CrossRef] [Google Scholar]
- Shiina I. An Effective Method for the Synthesis of Carboxylic Esters and Lactones Using Substituted Benzoic Anhydrides with Lewis Acid Catalysts. Tetrahedron 2004, 60, 1587–1599. 10.1016/j.tet.2003.12.013. [CrossRef] [Google Scholar]
- Shiina I.; Nakata K. The First Asymmetric Esterification of Free Carboxylic Acids with Racemic Alcohols Using Benzoic Anhydrides and Tetramisole Derivatives: An Application to the Kinetic Resolution of Secondary Benzylic Alcohols. Tetrahedron Lett. 2007, 48, 8314–8317. 10.1016/j.tetlet.2007.09.135. [CrossRef] [Google Scholar]
- Shiina I.; Nakata K.; Onda Y.-s. Kinetic Resolution of Racemic Carboxylic Acids Using Achiral Alcohols by the Promotion of Benzoic Anhydrides and Tetramisole Derivatives: Production of Chiral Nonsteroidal Anti-Inflammatory Drugs and Their Esters. Eur. J. Org. Chem. 2008, 2008, 5887–5890. 10.1002/ejoc.200800942. [CrossRef] [Google Scholar]
- Sidoli S.; Yuan Z.-F.; Lin S.; Karch K.; Wang X.; Bhanu N.; Arnaudo A. M.; Britton L.-M.; Cao X.-J.; Gonzales-Cope M.; et al. Drawbacks in the Use of Unconventional Hydrophobic Anhydrides for Histone Derivatization in Bottom-up Proteomics PTM Analysis. Proteomics 2015, 15, 1459–1469. 10.1002/pmic.201400483. [Europe PMC free article] [Abstract] [CrossRef] [Google Scholar]
- Chen F. M. F.; Stainauer R.; Benoiton N. L. Mixed Anhydrides in Peptide Synthesis. Reduction of Urethane Formation and Racemization Using N-Methylpiperidine as the Tertiary Amine Base. J. Org. Chem. 1983, 48, 2939–2941. 10.1021/jo00165a036. [CrossRef] [Google Scholar]
- Phan N. T. S.; Vu P. H. L.; Nguyen T. T. Expanding Applications of Copper-Based Metal-Organic Frameworks in Catalysis: Oxidative C-O Coupling by Direct C-H Activation of Ethers over Cu2(BPDC)2(BPY) as an Efficient Heterogeneous Catalyst. J. Catal. 2013, 306, 38–46. 10.1016/j.jcat.2013.06.006. [CrossRef] [Google Scholar]
- Liu M.; Wu J.; Hou H. Metal–Organic Framework (MOF)-Based Materials as Heterogeneous Catalysts for C–H Bond Activation. Chem.—Eur. J. 2019, 25, 2935–2948. 10.1002/chem.201804149. [Abstract] [CrossRef] [Google Scholar]
- Van Velthoven N.; Waitschat S.; Chavan S. M.; Liu P.; Smolders S.; Vercammen J.; Bueken B.; Bals S.; Lillerud K. P.; Stock N.; et al. Single-Site Metal-Organic Framework Catalysts for the Oxidative Coupling of Arenes: Via C-H/C-H Activation. Chem. Sci. 2019, 10, 3616–3622. 10.1039/c8sc05510f. [Europe PMC free article] [Abstract] [CrossRef] [Google Scholar]
- Mondal J.; Modak A.; Bhaumik A. Highly Efficient Mesoporous Base Catalyzed Knoevenagel Condensation of Different Aromatic Aldehydes with Malononitrile and Subsequent Noncatalytic Diels-Alder Reactions. J. Mol. Catal. A: Chem. 2011, 335, 236–241. 10.1016/j.molcata.2010.11.039. [CrossRef] [Google Scholar]
- Otomo R.; Osuga R.; Kondo J. N.; Kamiya Y.; Yokoi T. Cs-Beta with an Al-Rich Composition as a Highly Active Base Catalyst for Knoevenagel Condensation. Appl. Catal., A 2019, 575, 20–24. 10.1016/j.apcata.2019.02.014. [CrossRef] [Google Scholar]
- Beach G. J.; Hogan C. E.; Besong B. N.; Hogan G. A. Inclusion of Alkyl Alcohol Guest Molecules into a Copper (II)-Based Hydrogen-Bonded Metal-Organic Framework. J. Mol. Struct. 2019, 1195, 744–746. 10.1016/j.molstruc.2019.06.023. [CrossRef] [Google Scholar]
- Zhang D.-J.; Song T.-Y.; Wang L.; Shi J.; Xu J.-N.; Wang Y.; Ma K.-R.; Yin W.-R.; Zhang L.-R.; Fan Y. Hydrothermal Synthesis, Structure and Rare Ferromagnetic Property of a 3-D Nd(III) Metal-Organic Framework Based on Mixed Pyridine-2,5-Dicarboxylic Acid/Nicotinic Acid Ligands. Inorg. Chim. Acta 2009, 362, 299–302. 10.1016/j.ica.2008.03.103. [CrossRef] [Google Scholar]
- Zou G.-D.; Gong L.-K.; Liu L.; Zhang Q.; Zhao X.-H. Two Low-Dimensional Transition Metal Coordination Polymers Constructed from Thiophene-2,5-dicarboxylic Acid and N/O-Donor Ligands: Syntheses, Structures and Magnetic Property. Inorg. Chem. Commun. 2019, 99, 140–144. 10.1016/j.inoche.2018.11.018. [CrossRef] [Google Scholar]
- Yang T.; Xiang Q.; Feng L.; Dong C.; Zhang X.; Ning Z.; Lai X.; Gao D. Yttrium-Based Metal-Organic Frameworks: Controllable Synthesis, Growth Mechanism and the Phase Transformation to Y2O3:Eu3+ Phosphors. J. Lumin. 2019, 214, 116567.10.1016/j.jlumin.2019.116567. [CrossRef] [Google Scholar]
- Gao H.-L.; Yi L.; Zhao B.; Zhao X.-Q.; Cheng P.; Liao D.-Z.; Yan S.-P. Synthesis and Characterization of Metal–Organic Frameworks Based on 4-Hydroxypyridine-2,6-Dicarboxylic Acid and Pyridine-2,6-Dicarboxylic Acid Ligands. Inorg. Chem. 2006, 45, 5980–5988. 10.1021/ic060550j. [Abstract] [CrossRef] [Google Scholar]
- Wang Y.-P.; Li X.-Y.; Li H.-H.; Zhang H.-Z.; Sun H.-Y.; Guo Q.; Li H.; Niu Z. A Novel 3D Nd(III) Metal-Organic Frameworks Based on Furan-2,5-Dicarboxylic Acid Exhibits New Topology and Rare near-Infrared Luminescence Property. Inorg. Chem. Commun. 2016, 70, 27–30. 10.1016/j.inoche.2016.05.008. [CrossRef] [Google Scholar]
- Wang Z.; Huang Y.; Yang J.; Li Y.; Zhuang Q.; Gu J. The Water-Based Synthesis of Chemically Stable Zr-Based MOFs Using Pyridine-Containing Ligands and Their Exceptionally High Adsorption Capacity for Iodine. Dalton Trans. 2017, 46, 7412–7420. 10.1039/c7dt01084b. [Abstract] [CrossRef] [Google Scholar]
- Lin X.-M.; Niu J.-L.; Lin J.; Hu L.; Zhang G.; Cai Y.-P. A Luminescent Tb(III)-MOF Based on Pyridine-3, 5-Dicarboxylic Acid for Detection of Nitroaromatic Explosives. Inorg. Chem. Commun. 2016, 72, 69–72. 10.1016/j.inoche.2016.08.009. [CrossRef] [Google Scholar]
- Dai C.; Zhou X.; Jing X.; Li G.; Huo Q.; Liu Y. Assembly of Two Cu-Based Coordination Polymers from 2-(Pyridine-3-Yl)-1H-4,5-Imidazoledicarboxylate Ligand. Inorg. Chem. Commun. 2015, 52, 69–72. 10.1016/j.inoche.2015.01.010. [CrossRef] [Google Scholar]
- Zhao D.; Yue D.; Jiang K.; Zhang L.; Li C.; Qian G. Isostructural Tb3+ /Eu3+ Co-Doped Metal–Organic Framework Based on Pyridine-Containing Dicarboxylate Ligands for Ratiometric Luminescence Temperature Sensing. Inorg. Chem. 2019, 58, 2637–2644. 10.1021/acs.inorgchem.8b03225. [Abstract] [CrossRef] [Google Scholar]
- Bazargan M.; Mirzaei M.; Aghamohamadi M.; Tahmasebi M.; Frontera A. Supramolecular Assembly of a 2D Coordination Polymer Bearing Pyridine-N-Oxide-2,5-Dicarboxylic Acid and Copper Ion: X-Ray Crystallography and DFT Calculations. J. Mol. Struct. 2020, 1202, 127243.10.1016/j.molstruc.2019.127243. [CrossRef] [Google Scholar]
- Zhou X.; Wang H.; Jiang S.; Xiang G.; Tang X.; Luo X.; Li L.; Zhou X. Multifunctional Luminescent Material Eu(III) and Tb(III) Complexes with Pyridine-3,5-Dicarboxylic Acid Linker: Crystal Structures, Tunable Emission, Energy Transfer, and Temperature Sensing. Inorg. Chem. 2019, 58, 3780–3788. 10.1021/acs.inorgchem.8b03319. [Abstract] [CrossRef] [Google Scholar]
- Semerci F.; Yeşilel O. Z.; Soylu M. S.; Keskin S.; Büyükgüngör O. A Two-Dimensional Photoluminescent Cadmium(II) Coordination Polymer Containing a New Coordination Mode of Pyridine-2,3-Dicarboxylate: Synthesis, Structure and Molecular Simulations for Gas Storage and Separation Applications. Polyhedron 2013, 50, 314–320. 10.1016/j.poly.2012.10.009. [CrossRef] [Google Scholar]
- Han Z.-B.; Cheng X.-N.; Li X.-F.; Chen X.-M. Hydrothermal Syntheses and Structural Studies of Lanthanide Coordination Polymers InvolvingIn-Situ Decarboxylation and Their Luminescence Properties. Z. Anorg. Allg. Chem. 2005, 631, 937–942. 10.1002/zaac.200400462. [CrossRef] [Google Scholar]
- Han Z.-B.; Song Y.-J.; Ji J.-W.; Zhang W.; Han G.-X. A 3D Porous Indium(III) Coordination Polymer Involving in-Situ Ligand Synthesis. J. Solid State Chem. 2009, 182, 3067–3070. 10.1016/j.jssc.2009.08.024. [CrossRef] [Google Scholar]
- Zhang Y.; Wang Y.; Liu L.; Wei N.; Gao M.-L.; Zhao D.; Han Z.-B. Robust Bifunctional Lanthanide Cluster Based Metal–Organic Frameworks (MOFs) for Tandem Deacetalization–Knoevenagel Reaction. Inorg. Chem. 2018, 57, 2193–2198. 10.1021/acs.inorgchem.7b03084. [Abstract] [CrossRef] [Google Scholar]
- Amarante S. F.; Freire M. A.; Mendes D. T. S. L.; Freitas L. S.; Ramos A. L. D. Evaluation of Basic Sites of ZIFs Metal Organic Frameworks in the Knoevenagel Condensation Reaction. Appl. Catal., A 2017, 548, 47–51. 10.1016/j.apcata.2017.08.006. [CrossRef] [Google Scholar]
- Armarego W. L. F.; Chai C.Purification of Laboratory Chemicals, 2nd ed.; Butterworth-Heinemann Linacre House, Pergamon Press: Jordan Hill, Oxford, 2009; pp 1–529. [Google Scholar]
- Rajak R.; Saraf M.; Mobin S. M. Robust Heterostructures of a Bimetallic Sodium-Zinc Metal-Organic Framework and Reduced Graphene Oxide for High-Performance Supercapacitors. J. Mater. Chem. A 2019, 7, 1725–1736. 10.1039/c8ta09528k. [CrossRef] [Google Scholar]
- Dai P.-X.; Yang E.-C.; Wang X.-G.; Zhao X.-J. Synthesis, Crystal Structures and Fluorescent Properties of Two 2,2′-Biquinoline-4,4′-Dicarboxylate-Based Cadmium(II) and Cobalt(II) Complexes. Z. Anorg. Allg. Chem. 2008, 634, 1581–1586. 10.1002/zaac.200800008. [CrossRef] [Google Scholar]
- Shi Q.; Cao R.; Sun D.-F.; Hong M.-C.; Liang Y.-C. Solvothermal Syntheses and Crystal Structures of Two Metal Coordination Polymers with Double-Chain Structures. Polyhedron 2001, 20, 3287–3293. 10.1016/s0277-5387(01)00945-7. [CrossRef] [Google Scholar]
- Feng Y.; Han Z.; Peng J.; Hao X. Hydrothermal Synthesis and Crystal Structure of a Mixed-Valence Cu(I)/Cu(II) Complex: [Cu4(Ophen)4(Mtp)] (Hophen=2-Hydroxy-1,10′-Phenanthroline, Mtp=2-Methyl-Terephthalate Acid). J. Mol. Struct. 2005, 734, 171–176. 10.1016/j.molstruc.2004.09.017. [CrossRef] [Google Scholar]
- Rajak R.; Mohammad A.; Chandra P.; Mobin S. M. Catalytic Application of Tactically Aligned Cd(II)-Based Luminescent 3D-Supramolecular Networks. ChemistrySelect 2019, 4, 7162–7172. 10.1002/slct.201901214. [CrossRef] [Google Scholar]
- Kar A. K.; Srivastava R. An Efficient and Sustainable Catalytic Reduction of Carbon-Carbon Multiple Bonds, Aldehydes, and Ketones Using a Cu Nanoparticle Decorated Metal Organic Framework. New J. Chem. 2018, 42, 9557–9567. 10.1039/c8nj01704b. [CrossRef] [Google Scholar]
- Rajak R.; Saraf M.; Verma S. K.; Kumar R.; Mobin S. M. Dy(III)-Based Metal–Organic Framework as a Fluorescent Probe for Highly Selective Detection of Picric Acid in Aqueous Medium. Inorg. Chem. 2019, 58, 16065–16074. 10.1021/acs.inorgchem.9b02611. [Abstract] [CrossRef] [Google Scholar]
- Lu J.-L.; Zhang D.-S.; Li L.; Liu B.-P. Bis(Dimethylammonium) Bis(Pyridine-2,5-Dicarboxylato)Copper(II). Acta Crystallogr., Sect. E: Struct. Rep. Online 2006, 62, m3321–m3322. 10.1107/s1600536806047180. [CrossRef] [Google Scholar]
- Chen W.; Wang J.-Y.; Chen C.; Yue Q.; Yuan H.-M.; Chen J.-S.; Wang S.-N. Photoluminescent Metal-Organic Polymer Constructed from Trimetallic Clusters and Mixed Carboxylates. Inorg. Chem. 2003, 42, 944–946. 10.1021/ic025871j. [Abstract] [CrossRef] [Google Scholar]
- Xie L.; Liu S.; Gao B.; Zhang C.; Sun C.; Li D.; Su Z. A Three-Dimensional Porous Metal-Organic Framework with the Rutile Topology Constructed from Triangular and Distorted Octahedral Building Blocks. Chem. Commun. 2005, 18, 2402–2404. 10.1039/b501477h. [Abstract] [CrossRef] [Google Scholar]
- Rosi N. L.; Kim J.; Eddaoudi M.; Chen B.; O’Keeffe M.; Yaghi O. M. Rod Packings and Metal-Organic Frameworks Constructed from Rod-Shaped Secondary Building Units. J. Am. Chem. Soc. 2005, 127, 1504–1518. 10.1021/ja045123o. [Abstract] [CrossRef] [Google Scholar]
- Yen C.-H.; Chen C.-Y.; Shiu K.-B. Hydrothermal Synthesis and X-Ray Structural Characterization of Manganese, Nickel, and Cadmium Coordination Polymers Containing 2,3-Pyridinedicarboxylate as Multidentate Ligands. J. Chin. Chem. Soc. 2007, 54, 903–910. 10.1002/jccs.200700130. [CrossRef] [Google Scholar]
- Burrows A. D.; Cassar K.; Friend R. M. W.; Mahon M. F.; Rigby S. P.; Warren J. E. Solvent hydrolysis and templating effects in the synthesis of metal–organic frameworks. CrystEngComm 2005, 7, 548–550. 10.1039/b509460g. [CrossRef] [Google Scholar]
- Zhang B.-F.; Xie C.-Z.; Wang X.-Q.; Shen G.-Q.; Shen D.-Z. Poly[[Hexaaquabis(Μ3-Pyidine-2,5-Dicarboxylato-κ 4O:O′,N:O″) Bis(μ 2-Pyridine-2,5-Dicarboxylato-κ 3O:O′,N)Dieuropium(III)Copper(II)]Dihydrate]. Acta Crystallogr., Sect. E: Struct. Rep. Online 2006, 62, m297–m299. 10.1107/s1600536806000948. [CrossRef] [Google Scholar]
- Mao L.; Rettig S. J.; Thompson R. C.; Trotter J.; Xia S. 2,3-Pyrazinedicarboxylates of Cobalt(II), Nickel(II), and Copper(II); Magnetic Properties and Crystal Structures. Can. J. Chem. 1996, 74, 433–444. 10.1139/v96-047. [CrossRef] [Google Scholar]
- Baca S. G.; Malinovskii S. T.; Franz P.; Ambrus C.; Stoeckli-Evans H.; Gerbeleu N.; Decurtins S. Synthesis, Structure and Magnetic Properties of Cobalt(II) and Copper(II) Coordination Polymers Assembled by Phthalate and 4-Methylimidazole. J. Solid State Chem. 2004, 177, 2841–2849. 10.1016/j.jssc.2004.05.001. [CrossRef] [Google Scholar]
- Wei J.; Qiu C.; Tang C. Y.; Wang R.; Fane A. G. Synthesis and Characterization of Flat-Sheet Thin Film Composite Forward Osmosis Membranes. J. Membr. Sci. 2011, 372, 292–302. 10.1016/j.memsci.2011.02.013. [CrossRef] [Google Scholar]
- Wang R.; Shi L.; Tang C. Y.; Chou S.; Qiu C.; Fane A. G. Characterization of Novel Forward Osmosis Hollow Fiber Membranes. J. Membr. Sci. 2010, 355, 158–167. 10.1016/j.memsci.2010.03.017. [CrossRef] [Google Scholar]
- Sukitpaneenit P.; Chung T.-S. Molecular Elucidation of Morphology and Mechanical Properties of PVDF Hollow Fiber Membranes from Aspects of Phase Inversion, Crystallization and Rheology. J. Membr. Sci. 2009, 340, 192–205. 10.1016/j.memsci.2009.05.029. [CrossRef] [Google Scholar]
- De R. R. L.; Albuquerque D. A. C.; Cruz T. G. S.; Yamaji F. M.; Leite F. L. Measurement of the Nanoscale Roughness by Atomic Force Microscopy: Basic Principles and Applications. At. Force Microsc.: Imaging, Meas. Manipulating Surf. At. Scale 2012, 256, 147.10.5772/37583. [CrossRef] [Google Scholar]
- Panda S.; Panzade A.; Sarangi M.; Roy Chowdhury S. K. Spectral Approach on Multiscale Roughness Characterization of Nominally Rough Surfaces. J. Tribol. 2016, 139, 031402.10.1115/1.4034215. [CrossRef] [Google Scholar]
- Sonkar P. K.; Prakash K.; Yadav M.; Ganesan V.; Sankar M.; Gupta R.; Yadav D. K. Co(II)-Porphyrin-Decorated Carbon Nanotubes as Catalysts for Oxygen Reduction Reactions: An Approach for Fuel Cell Improvement. J. Mater. Chem. A 2017, 5, 6263–6276. 10.1039/c6ta10482g. [CrossRef] [Google Scholar]
- Farokh Payam A.. Application of Atomic Force Microscopy to Study Metal–Organic Frameworks Materials and Composites; Springer: Singapore, 2018; pp 37–73. [Google Scholar]
- Yam V. W.-W.; Wong K. M.-C. Luminescent Metal Complexes of d6, d8 and d10 Transition Metal Centres. Chem. Commun. 2011, 47, 11579–11592. 10.1039/c1cc13767k. [Abstract] [CrossRef] [Google Scholar]
- Chakkaradhari G.; Chen Y.-T.; Karttunen A. J.; Dau M. T.; Jänis J.; Tunik S. P.; Chou P.-T.; Ho M.-L.; Koshevoy I. O. Luminescent Triphosphine Cyanide d10 Metal Complexes. Inorg. Chem. 2016, 55, 2174–2184. 10.1021/acs.inorgchem.5b02581. [Abstract] [CrossRef] [Google Scholar]
- Cui Y.; Yue Y.; Qian G.; Chen B. Luminescent Functional Metal–Organic Frameworks. Chem. Rev. 2012, 112, 1126–1162. 10.1021/cr200101d. [Abstract] [CrossRef] [Google Scholar]
- Kreno L. E.; Leong K.; Farha O. K.; Allendorf M.; Van Duyne R. P.; Hupp J. T. Metal À Organic Framework Materials as Chemical Sensors. Chem. Rev. 2012, 112, 1105–1125. 10.1021/cr200324t. [Abstract] [CrossRef] [Google Scholar]
- Ghorai P.; Dey A.; Hazra A.; Dutta B.; Brandão P.; Ray P. P.; Banerjee P.; Saha A. Cd(II) Based Coordination Polymer Series: Fascinating Structures, Efficient Semiconductors, and Promising Nitro Aromatic Sensing. Cryst. Growth Des. 2019, 19, 6431–6447. 10.1021/acs.cgd.9b00891. [CrossRef] [Google Scholar]
- Natour R. A.; Ali Z. K.; Assoud A.; Hmadeh M. Two-Dimensional Metal-Organic Framework Nanosheets as a Dual Ratiometric and Turn-off Luminescent Probe. Inorg. Chem. 2019, 58, 10912–10919. 10.1021/acs.inorgchem.9b01315. [Abstract] [CrossRef] [Google Scholar]
- Pamei M.; Puzari A. Luminescent Transition Metal–Organic Frameworks: An Emerging Sensor for Detecting Biologically Essential Metal Ions. Nano-Struct. Nano-Objects 2019, 19, 100364.10.1016/j.nanoso.2019.100364. [CrossRef] [Google Scholar]
- Li F.; Sun M.-L.; Zhang X.; Yao Y.-G. Diverse Structures and Luminescence Properties of Nine Novel Zn/Cd(II)-Organic Architectures Assembled by Two Different Rigid Ligands. Cryst. Growth Des. 2019, 19, 4404–4416. 10.1021/acs.cgd.9b00202. [CrossRef] [Google Scholar]
- Yin W.-X.; Liu Y.-T.; Ding Y.-J.; Lin Q.; Lin X.-M.; Wu C.-L.; Yao X.-D.; Cai Y.-P. Construction of Variable Dimensional Cadmium(Ii) Coordination Polymers from Pyridine-2,3-Dicarboxylic Acid. CrystEngComm 2015, 17, 3619–3626. 10.1039/c5ce00378d. [CrossRef] [Google Scholar]
- Lin J.-G.; Zang S.-Q.; Tian Z.-F.; Li Y.-Z.; Xu Y.-Y.; Zhu H.-Z.; Meng Q.-J. Metal-Organic Frameworks Constructed from Mixed-Ligand 1,2,3,4-Tetra-(4- Pyridyl)-Butane and Benzene-Polycarboxylate Acids: Syntheses, Structures and Physical Properties. CrystEngComm 2007, 9, 915–921. 10.1039/b708389k. [CrossRef] [Google Scholar]
- Lu W.-G.; Jiang L.; Feng X.-L.; Lu T.-B. Three 3D Coordination Polymers Constructed by Cd(II) and Zn(II) with Imidazole-4,5-Dicarboxylate and 4,4‘-Bipyridyl Building Blocks. Cryst. Growth Des. 2006, 6, 564–571. 10.1021/cg0505158. [CrossRef] [Google Scholar]
- Saracini C.; Malik D. D.; Sankaralingam M.; Lee Y.-M.; Nam W.; Fukuzumi S. Enhanced Electron-Transfer Reactivity of a Long-Lived Photoexcited State of a Cobalt–Oxygen Complex. Inorg. Chem. 2018, 57, 10945–10952. 10.1021/acs.inorgchem.8b01571. [Abstract] [CrossRef] [Google Scholar]
- Vallejos J.; Brito I.; Cárdenas A.; Bolte M.; Conejeros S.; Alemany P.; Llanos J. Self-Assembly of Discrete Metallocycles versus Coordination Polymers Based on Cu(I) and Ag(I) Ions and Flexible Ligands: Structural Diversification and Luminescent Properties. Polymers 2016, 8, 46.10.3390/polym8020046. [Europe PMC free article] [Abstract] [CrossRef] [Google Scholar]
- Huang F.-P.; Yang Z.-M.; Yao P.-F.; Yu Q.; Tian J.-L.; Bian H.-D.; Yan S.-P.; Liao D.-Z.; Cheng P. Coordination Assemblies of the CdII-BDC/Bpt Mixed-Ligand System: Positional Isomeric Effect, Structural Diversification and Luminescent Properties. CrystEngComm 2013, 15, 2657–2668. 10.1039/c3ce26905a. [CrossRef] [Google Scholar]
- Budagumpi S.; Kim K.-H.; Kim I. Catalytic and Coordination Facets of Single-Site Non-Metallocene Organometallic Catalysts with N-Heterocyclic Scaffolds Employed in Olefin Polymerization. Coord. Chem. Rev. 2011, 255, 2785–2809. 10.1016/j.ccr.2011.04.013. [CrossRef] [Google Scholar]
- Cai K.; Tan W.; Zhao N.; He H. Design and Assembly of a Hierarchically Micro-and Mesoporous MOF as a Highly Efficient Heterogeneous Catalyst for Knoevenagel Condensation Reaction. Cryst. Growth Des. 2020, 20, 4845–4851. 10.1021/acs.cgd.0c00636. [CrossRef] [Google Scholar]
- Jadhav A. L.; Yadav G. D. Clean Synthesis of Benzylidenemalononitrile by Knoevenagel Condensation of Benzaldehyde and Malononitrile: Effect of Combustion Fuel on Activity and Selectivity of Ti-Hydrotalcite and Zn-Hydrotalcite Catalysts. J. Chem. Sci. 2019, 131, 79.10.1007/s12039-019-1641-6. [CrossRef] [Google Scholar]
- Das A.; Anbu N.; Dhakshinamoorthy A.; Biswas S. A Highly Catalytically Active Hf(IV) Metal-Organic Framework for Knoevenagel Condensation. Microporous Mesoporous Mater. 2019, 284, 459–467. 10.1016/j.micromeso.2019.04.057. [CrossRef] [Google Scholar]
- Yao N.; Tan J.; Liu Y.; Hu Y. L. An Efficient and Reusable Multifunctional Composite Magnetic Nanocatalyst for Knoevenagel Condensation. Synlett 2019, 30, 699–702. 10.1055/s-0037-1612076. [CrossRef] [Google Scholar]
- Lolak N.; Kuyuldar E.; Burhan H.; Goksu H.; Akocak S.; Sen F. Composites of Palladium-Nickel Alloy Nanoparticles and Graphene Oxide for the Knoevenagel Condensation of Aldehydes with Malononitrile. ACS Omega 2019, 4, 6848–6853. 10.1021/acsomega.9b00485. [Europe PMC free article] [Abstract] [CrossRef] [Google Scholar]
- Varga G.; Kukovecz Á.; Kónya Z.; Sipos P.; Pálinkó I. Green and Selective Toluene Oxidation–Knoevenagel-Condensation Domino Reaction over Ce- and Bi-Based CeBi Mixed Oxide Mixtures. J. Catal. 2020, 381, 308–315. 10.1016/j.jcat.2019.11.011. [CrossRef] [Google Scholar]
- Yousefian M.; Rafiee Z. Cu-Metal-Organic Framework Supported on Chitosan for Efficient Condensation of Aromatic Aldehydes and Malononitrile. Carbohydr. Polym. 2020, 228, 115393.10.1016/j.carbpol.2019.115393. [Abstract] [CrossRef] [Google Scholar]
- Ghorbanloo M.; Safarifard V.; Morsali A. Heterogeneous Catalysis with a Coordination Modulation Synthesized MOF: Morphology-Dependent Catalytic Activity. New J. Chem. 2017, 41, 3957–3965. 10.1039/c6nj04065a. [CrossRef] [Google Scholar]
- Masoomi M. Y.; Beheshti S.; Morsali A. Shape Control of Zn(II) Metal–Organic Frameworks by Modulation Synthesis and Their Morphology-Dependent Catalytic Performance. Cryst. Growth Des. 2015, 15, 2533–2538. 10.1021/acs.cgd.5b00304. [CrossRef] [Google Scholar]
- Anbu N.; Maheswari R.; Elamathi V.; Varalakshmi P.; Dhakshinamoorthy A. Chitosan as a Biodegradable Heterogeneous Catalyst for Knoevenagel Condensation for Benzaldehydes and Ethylcyanoacetamide. Catal. Commun. 2020, 138, 105954.10.1016/j.catcom.2020.105954. [CrossRef] [Google Scholar]
- Liu H.; Xi F.-G.; Sun W.; Yang N.-N.; Gao E.-Q. Amino- and Sulfo-Bifunctionalized Metal–Organic Frameworks: One-Pot Tandem Catalysis and the Catalytic Sites. Inorg. Chem. 2016, 55, 5753–5755. 10.1021/acs.inorgchem.6b01057. [Abstract] [CrossRef] [Google Scholar]
- Dhakshinamoorthy A.; Heidenreich N.; Lenzen D.; Stock N. Knoevenagel Condensation Reaction Catalysed by Al-MOFs with CAU-1 and CAU-10-Type Structures. CrystEngComm 2017, 19, 4187–4193. 10.1039/c6ce02664h. [CrossRef] [Google Scholar]
- Ramaiah M. M.; Shivananju N. S.; Shubha P. B. A Facile, Efficient and Solvent-Free Titanium (IV) Ethoxide Catalysed Knoevenagel Condensation of Aldehydes and Active Methylenes. Lett. Org. Chem. 2020, 17, 107–115. 10.2174/1570178616666190401194641. [CrossRef] [Google Scholar]
- Jiang W.-L.; Fu Q.-J.; Yao B.-J.; Ding L.-G.; Liu C.-X.; Dong Y.-B. Smart PH-Responsive Polymer-Tethered and Pd NP-Loaded NMOF as the Pickering Interfacial Catalyst for One-Pot Cascade Biphasic Reaction. ACS Appl. Mater. Interfaces 2017, 9, 36438–36446. 10.1021/acsami.7b12166. [Abstract] [CrossRef] [Google Scholar]
- Opanasenko M.; Dhakshinamoorthy A.; Shamzhy M.; Nachtigall P.; Horáček M.; Garcia H.; Čejka J. Comparison of the Catalytic Activity of MOFs and Zeolites in Knoevenagel Condensation. Catal. Sci. Technol. 2013, 3, 500–507. 10.1039/c2cy20586f. [CrossRef] [Google Scholar]
- Hartmann M.; Fischer M. Amino-Functionalized Basic Catalysts with MIL-101 Structure. Microporous Mesoporous Mater. 2012, 164, 38–43. 10.1016/j.micromeso.2012.06.044. [CrossRef] [Google Scholar]
- Kim H.-C.; Huh S.; Kim S.-J.; Kim Y. Selective Carbon Dioxide Sorption and Heterogeneous Catalysis by a New 3D Zn-MOF with Nitrogen-Rich 1D Channels. Sci. Rep. 2017, 7, 17185.10.1038/s41598-017-17584-8. [Europe PMC free article] [Abstract] [CrossRef] [Google Scholar]
- Bai R.; Song Y.; Li Y.; Yu J. Creating Hierarchical Pores in Zeolite Catalysts. Trends Chem. 2019, 1, 601–611. 10.1016/j.trechm.2019.05.010. [CrossRef] [Google Scholar]
- Han X.; Xu Y.-X.; Yang J.; Xu X.; Li C.-P.; Ma J.-F. Metal-Assembled, Resorcin[4]Arene-Based Molecular Trimer for Efficient Removal of Toxic Dichromate Pollutants and Knoevenagel Condensation Reaction. ACS Appl. Mater. Interfaces 2019, 11, 15591–15597. 10.1021/acsami.9b02068. [Abstract] [CrossRef] [Google Scholar]
- Schejn A.; Mazet T.; Falk V.; Balan L.; Aranda L.; Medjahdi G.; Schneider R. Fe3O4@ZIF-8: Magnetically Recoverable Catalysts by Loading Fe3O4 Nanoparticles inside a Zinc Imidazolate Framework. Dalton Trans. 2015, 44, 10136–10140. 10.1039/c5dt01191d. [Abstract] [CrossRef] [Google Scholar]
- Basu D.; Kumar S.; Sudhir S.; Bandichhor R. Transition Metal Catalyzed C-H Activation for the Synthesis of Medicinally Relevant Molecules: A Review. J. Chem. Sci. 2018, 130, 71.10.1007/s12039-018-1468-6. [CrossRef] [Google Scholar]
- Gandeepan P.; Müller T.; Zell D.; Cera G.; Warratz S.; Ackermann L. 3d Transition Metals for C-H Activation. Chem. Rev. 2019, 119, 2192–2452. 10.1021/acs.chemrev.8b00507. [Abstract] [CrossRef] [Google Scholar]
- Saberi D.; Shojaeyan F.; Niknam K. Oxidative Self-Coupling of Aldehydes in the Presence of CuCl2/TBHP System: Direct Access to Symmetrical Anhydrides. Tetrahedron Lett. 2016, 57, 566–569. 10.1016/j.tetlet.2015.12.095. [CrossRef] [Google Scholar]
- Corma A.; Fornés V.; Martín-Aranda R. M.; García H.; Primo J. Zeolites as Base Catalysts: Condensation of Aldehydes with Derivatives of Malonic Esters. Appl. Catal. 1990, 59, 237–248. 10.1016/S0166-9834(00)82201-0. [CrossRef] [Google Scholar]
- Chen H.; Fan L.; Hu T.; Zhang X. 6s-3d {Ba3Zn4}–Organic Framework as an Effective Heterogeneous Catalyst for Chemical Fixation of CO2 and Knoevenagel Condensation Reaction. Inorg. Chem. 2021, 60, 3384–3392. 10.1021/acs.inorgchem.0c03736. [Abstract] [CrossRef] [Google Scholar]
- Appaturi J. N.; Ratti R.; Phoon B. L.; Batagarawa S. M.; Din I. U.; Selvaraj M.; Ramalingam R. J. A Review of the Recent Progress on Heterogeneous Catalysts for Knoevenagel Condensation. Dalton Trans. 2021, 50, 4445–4469. 10.1039/D1DT00456E. [Abstract] [CrossRef] [Google Scholar]
- Deng J.-B.; Wang X.; Ni Z.-Q.; Zhu F. Two Co(II)-Based Metal-Organic Frameworks: Catalytic Knoevenagel Condensation Reactions and Inhibitory Activity on the Scar Tissue Hyperplasia by Reducing the Activity of the VEGF Signaling Pathway. Arab. J. Chem. 2020, 13, 7482–7489. 10.1016/j.arabjc.2020.08.023. [CrossRef] [Google Scholar]
- Rahmati E.; Rafiee Z. Synthesis of Co-MOF/COF Nanocomposite: Application as a Powerful and Recoverable Catalyst in the Knoevenagel Reaction. J. Porous Mater. 2021, 28, 19–27. 10.1007/s10934-020-00965-2. [CrossRef] [Google Scholar]
- Chen S.-S.; Zhang Z.-Y.; Liao R.-B.; Zhao Y.; Wang C.; Qiao R.; Liu Z.-D. A Photoluminescent Cd(II) Coordination Polymer with Potential Active Sites Exhibiting Multiresponsive Fluorescence Sensing for Trace Amounts of NACs and Fe3+ and Al3+ Ions. Inorg. Chem. 2021, 60, 4945–4956. 10.1021/acs.inorgchem.1c00022. [Abstract] [CrossRef] [Google Scholar]
- Rafiee Z. Fabrication of Efficient Zn-MOF/COF Catalyst for the Knoevenagel Condensation Reaction. J. Iran. Chem. Soc. 2021, 10.1007/s13738-021-02221-z. [CrossRef] [Google Scholar]
Articles from ACS Omega are provided here courtesy of American Chemical Society
Full text links
Read article at publisher's site: https://doi.org/10.1021/acsomega.1c01155
Read article for free, from open access legal sources, via Unpaywall:
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8158822
Citations & impact
Impact metrics
Citations of article over time
Article citations
Urea-rich porous organic polymer as a hydrogen bond catalyst for Knoevenagel condensation reaction and synthesis of 2,3-dihydroquinazolin-4(1H)-ones.
RSC Adv, 14(2):1094-1105, 02 Jan 2024
Cited by: 0 articles | PMID: 38174287 | PMCID: PMC10759279
Solvent-free cross aldol condensation of aldehydes and ketones over SrMo1-xNixO3-δ perovskite nanocrystals as heterogeneous catalysts.
Heliyon, 9(10):e21038, 14 Oct 2023
Cited by: 0 articles | PMID: 37920271 | PMCID: PMC10618990
Electro-organic green synthesis of dicyano-2-(2-oxoindolin-3-ylidene) malononitriles using molecular iodine as catalyst.
RSC Adv, 13(22):15024-15030, 16 May 2023
Cited by: 0 articles | PMID: 37207098 | PMCID: PMC10189244
A Reusable Efficient Green Catalyst of 2D Cu-MOF for the Click and Knoevenagel Reaction.
Molecules, 26(17):5296, 31 Aug 2021
Cited by: 1 article | PMID: 34500728 | PMCID: PMC8434330
Data
Data behind the article
This data has been text mined from the article, or deposited into data resources.
BioStudies: supplemental material and supporting data
Similar Articles
To arrive at the top five similar articles we use a word-weighted algorithm to compare words from the Title and Abstract of each citation.
Highly Robust 3s-3d {CaZn}-Organic Framework for Excellent Catalytic Performance on Chemical Fixation of CO2 and Knoevenagel Condensation Reaction.
ACS Appl Mater Interfaces, 12(49):54884-54892, 24 Nov 2020
Cited by: 2 articles | PMID: 33231426
Highly Efficient Bifunctional Amide Functionalized Zn and Cd Metal Organic Frameworks for One-Pot Cascade Deacetalization-Knoevenagel Reactions.
Front Chem, 7:699, 25 Oct 2019
Cited by: 2 articles | PMID: 31709229 | PMCID: PMC6824099
Hydrothermal Assembly, Structural Multiplicity, and Catalytic Knoevenagel Condensation Reaction of a Series of Coordination Polymers Based on a Pyridine-Tricarboxylic Acid.
Molecules, 28(22):7474, 08 Nov 2023
Cited by: 0 articles | PMID: 38005197
Triazole-directed fabrication of polyoxovanadate-based metal-organic frameworks as efficient multifunctional heterogeneous catalysts for the Knoevenagel condensation and oxidation of alcohols.
Dalton Trans, 50(29):10082-10091, 01 Jul 2021
Cited by: 1 article | PMID: 34213516
An overview of metal-free sustainable nitrogen-based catalytic knoevenagel condensation reaction.
Org Biomol Chem, 20(11):2164-2186, 16 Mar 2022
Cited by: 3 articles | PMID: 35225313
Review
Funding
Funders who supported this work.
Department of Science and Technology, Ministry of Science and Technology (1)
Grant ID: IFA12-CH-66