Amide Functionalized Mesoporous MOF LOCOM-1 as a Stable Highly Active Basic Catalyst for Knoevenagel Condensation Reaction

Acyl-amide is extensively used as functional group and is a superior contender for the design of MOFs with the guest accessible functional organic sites. A novel acyl-amide-containing tetracarboxylate ligand, bis(3,5-dicarboxy-pheny1)terephthalamide, has been successfully synthesized. The H₄L linker has some fascinating attributes as follows: (i) four carboxylate moieties as the coordination sites confirm affluent coordination approaches to figure a diversity of structure; (ii) two acyl-amide groups as the guest interaction sites can engender guest molecules integrated into the MOF networks through H-bonding interfaces and have a possibility to act as functional organic sites for the condensation reaction. A mesoporous MOF ([Cu₂(L)(H₂O)₃]·4DMF·6H₂O) has been prepared in order to produce the amide FOS within the MOF, which will work as guest accessible sites. The prepared MOF was characterized by CHN analysis, PXRD, FTIR spectroscopy, and SEM analysis. The MOF showed superior catalytic activity for Knoevenagel condensation. The catalytic system endures a broad variety of the functional groups and presents high to modest yields of aldehydes containing electron withdrawing groups (4-chloro, 4-fluoro, 4-nitro), offering a yield > 98 in less reaction time as compared to aldehydes with electron donationg groups (4-methyl). The amide decorated MOF (LOCOM-1-) as a heterogeneous catalyst can be simply recovered by centrifugation and recycled again without a flagrant loss of its catalytic efficiency.

Zinc(II) Carboxylate Coordination Polymers with Versatile Applications

This review considers the applications of Zn(II) carboxylate-based coordination polymers (Zn-CBCPs), such as sensors, catalysts, species with potential in infections and cancers treatment, as well as storage and drug-carrier materials. The nature of organic luminophores, especially both the rigid carboxylate and the ancillary N-donor bridging ligand, together with the alignment in Zn-CBCPs and their intermolecular interaction modulate the luminescence properties and allow the sensing of a variety of inorganic and organic pollutants. The ability of Zn(II) to act as a good Lewis acid allowed the involvement of Zn-CBCPs either in dye elimination from wastewater through photocatalysis or in pathogenic microorganism or tumor inhibition. In addition, the pores developed inside of the network provided the possibility for some species to store gaseous or liquid molecules, as well as to deliver some drugs for improved treatment.

Two Cu(i) coordination polymers based on a new benzimidazolyl-tetrazolyl heterotopic ligand for visible-light-driven photocatalytic dye degradation

Two Cu(i) CPs based on a new heterotopic tripodal ligand were constructed and their visible-light-driven photocatalytic performance were studied.

Syntheses, crystal structures, and fluorescent properties of three coordination polymers with 5-sulfoisophthalic acid anion and 4-phenylpyridine

Three coordination polymers—{[Ag2(SIP)(4-pp)]·[Ag(4-pp)2]·H2O}n, [Pb4(SIP)2( μ3-OH)2(H2O)2]n, and {[Zn2(SIP)2(4-pp)4][Zn(4-pp)2(H2O)4]·4H2O}n (SIP = 5-sulfoisophthalic acid anion, 4-pp = 4-phenylpyridine)—are constructed under hydrothermal or solvothermal conditions using sodium m-phthalate 5-sulfonate (NaH2SIP) and 4-phenylpyridine as ligands. The structures of the three complexes are determined by single-crystal X-ray diffraction, powder X-ray diffraction, thermogravimetric analyses, Fourier-transform infrared analysis, and photoluminescence. The fluorescent properties of the complexes in the solid state are investigated at room temperature, and the results indicate that they all show photoluminescent properties.

Cobalt-Based Metal-Organic Frameworks for Adsorption of CO2 and C2 Hydrocarbons: Effect of Auxiliary Ligands with Different Functional Groups

Recently, metal-organic frameworks (MOFs) have been investigated as potential materials for CO₂ capture and light hydrocarbon storage/separation due to their high porosity, large surface area, and tunable skeleton structures. In this work, the six cobalt-based MOFs 1-6 were successfully synthesized under solvothermal conditions by a mixed-ligand strategy. 1 and 2 have the same framework structure with a topology of {4²·5}₂{4⁴·5¹⁰·6⁷·7⁶·8}, while the structures of the 3-6 frameworks are the same with a topology of {4²·5}₂{4⁴·5¹⁰·6⁹·7⁴·8}. The adsorption properties of these MOFs for CO₂ and C₂ hydrocarbons were then investigated, and the effect of the functional groups was discussed. The results revealed that the introduction of amino and bromo groups could effectively strengthen the adsorption performance.

Luminescent coordination polymers constructed using a mixed-ligand strategy for highly selective luminescence sensing of nitrobenzene, Fe3+ and Cr2O72− ions and photodegradation of rhodamine B

Using a mixed ligand strategy, ten new LCPs were constructed. They all display highly sensitive and selective luminescence sensing for NB, Cr₂O₇²⁻and Fe³⁺ ions. Moreover, 3–10 also exhibit high photocatalytic activities toward the degradation of RhB.

Coordination Assemblies of Zn(II) Coordination Polymers: Positional Isomeric Effect and Optical Properties

Two Zn(II) coordination polymers (CPs) [Zn(L)(pphda)] (1) and [Zn(L)(ophda)]·H2O (2) were prepared by reactions of ZnSO4·7H2O based on the N-donor 1,4-di(1H-imidazol-4-yl)benzene (L) ligand and two flexible carboxylic acids isomers of 1,4-phenylenediacetic acid (H2pphda) and 1,2-phenylenediacetic acid (H2ophda) as mixed ligands, respectively. Structures of CPs 1 and 2 were characterized by elemental analysis, Infrared spectroscopy (IR), thermogravimetric analysis and single-crystal X-ray diffraction. The CP 1 is a fourfold interpenetrating 66-diamond (dia) architecture, while 2 is a 2D (4, 4) square lattice (sql) layer based on the Zn2(cis-1,2-ophda2−)2 binuclear Zn(II) subunits. The luminescent property, including luminescence lifetime and quantum yield (QY), have been investigated for CPs 1 and 2.

Series of Cadmium(II) Coordination Polymers Based on a Versatile Multi-N-Donor Tecton or Mixed Carboxylate Ligands: Synthesis, Structure, and Selectively Sensing Property

Five Cd(II) metal-organic frameworks (MOFs), [Cd(HL)₂] (1), [Cd(HL)₂(H₂O)₂] (2), [Cd₃(HL)₂(obda)₂] (3), [Cd₂(HL)₂(ohmbda)(DMA)(H₂O)] (4), and [Cd₂(HL)(btc)(H₂O)₂]·3H₂O (5), were prepared by reactions of Cd(NO₃)₂·4H₂O with 1-(1H-imidazol-4-yl)-4-(4H-tetrazol-5-yl)benzene (H₂L) or mixed carboxylate ancillary ligands of 1,2-benzenedicarboxylic acid (H₂obda), 5-hydroxy-1,3-benzenedicarboxylic acid (H₂ohmbda), and 1,3,5-benzenetricarboxylic acid (H₃btc), respectively. Their structures have been characterized by single-crystal X-ray diffraction, elemental analysis, infrared spectroscopy (IR), thermogravimetric analysis, and powder X-ray diffraction. Compounds 1 and 2 are supramolecular isomeric frameworks without consideration of the solvent molecules. Complex 1 exhibits a binodal (3, 5)-connected two-dimensional (2D) layer structure with the point (Schläfli) symbol of (5²·6)(5⁵·6⁴·7), while complex 2 shows a 2D + 2D → 3D (three-dimensional) framework. Complex 3 is a (3, 5, 6)-connected tetranodal 3D net with the point (Schläfli) symbol of (4·8²)₂(4⁵·6·8⁴)₂(4⁵·6⁵)₂(4⁸·6⁶·8). Compound 4 is a (3, 3, 8)-connected trinodal 3D net with the point (Schläfli) symbol based on a binuclear [Cd₂N₂O] subunit, while 5 is a 2-nodal (3, 4)-connected 2D V₂O₅-type network based on [Cd₂N₂(COO)₂] SBU. The studies of molecular sensing properties show that the luminescent MOFs can be employed as fluorescent sensors for the detection of Fe³⁺ and nitro compounds. Compound 1 and 3 exhibit quenching responses for Fe³⁺ in dimethylformamide solution with detection limits of 2.3 × 10^-6 and 8.6 × 10^-7 M, respectively. Meanwhile, compound 5 can sense 4-nitrophenol with a detection limit as low as 5.75 × 10^-7 M.

Metal(II) Coordination Polymers Derived from Mixed 4-Imidazole Ligands and Carboxylates: Syntheses, Topological Structures, and Properties

Four new metal⁻organic coordination polymers [Cu(L)(mpa)]·3H₂O (1), [Co(L)(mpa)]·H₂O (2), [Zn(L)(mpa)]·H₂O (3), and [Cd(L)(mpa)(H₂O)]·H₂O (4) were synthesized by reactions of the corresponding metal(II) salts based on mixed ligands of 1,4-di(1H-imidazol-4-yl)benzene (L) and 4-methylphthalic acid (H₂mpa), respectively. The structures of the complexes were characterized by elemental analysis, FT-IR spectroscopy, and single-crystal X-ray diffraction. Compound 1 exhibits a binodal 4-connected three dimensional (3D) architecture with (6⁵·8)-CdSO₄ topology, while complexes 2 and 3 are isostructural and have two-dimensional (2D) layer structure with (4, 4) sql topology based on the binuclear metal subunits. Complex 4 has the same 2D layer structure with (4, 4) sql topology as complexes 2 and 3, but the inclined interpenetration of parallel sets of layers result in the formation with 2D + 2D → 3D framework. The activated sample 1 shows selective CO₂ uptake over N₂. The photoluminiscent properties together with quantum yield (QY) and luminescence lifetime are also investigated for complexes 3 and 4 in the solid state at room temperature.

Three new Zn-based metal–organic frameworks exhibiting selective fluorescence sensing and photocatalytic activity

Three MOFs with different 2D networks have been crystallised in a one-pot solvothermal reaction. They all display high sensitivity in the detection of ACE and relatively good photocatalytic activity in the degradation of RhB.

Set of Multifunctional Azo Functionalized Semiconducting Cd(II)-MOFs Showing Photoswitching Property and Selective CO2 Adsorption

Syntheses, structural characterizations, photoluminescence, and adsorption properties of three new azo-functionalized Cd(II)-MOFs, namely, {[Cd(azbpy)(msuc)]·2.5(H₂O)}_n (2), {[Cd(azbpy)(mglu)]·5(H₂O)}_n (3), and {[Cd_1.5(azbpy)₂(glu)]·(NO₃)·MeOH}_n (4) [where msuc^2- = methylsuccinate; mglut^2- = methylglutarate; glut^2- = glutarate; azbpy = 4,4'-azobispyridine] have been reported. The compounds show different structures only with the variation of aliphatic dicarboxylates. The photoswitching behavior for the above-mentioned newly synthesized Cd(II)-MOFs along with one of our previously reported other azo-functionalized Cd(II)-MOF, namely, {[Cd(azbpy)(suc)]·2(H₂O)}_n (1), has been studied extensively. At photoilluminated condition, the conductivity values can draw a clear structure-property relationship among the structures of compounds 1-4. Single crystal structural analysis reveals that all the compounds exhibit a three-dimensional (3D) framework connected by azbpy linker and respective aliphatic dicarboxylate through their bis-chelating mono/bis oxo-bridging fashion. Compounds 1-3 exhibit an iso-structural honeycomb like 3D framework showing the same coordination environments, where the metal-carboxylate 2D sheets of compounds 1-3 are pillared by N,N'-donor azbpy linkers. On the other hand, compound 4 exhibits a 2-fold interpenetrated 3D framework with a little difference in its coordination environment and the pillaring of 1D metal-carboxylate ladder by azbpy linkers. All the compounds significantly demonstrate their enhanced sensitivity under light rather than the dark condition. The gas and solvent vapor sorption studies have been performed for the synthesized compounds 2-4. Moreover, compound 2 exhibits an enhanced type IV selective CO₂ adsorption isotherm over N₂ along with the appearance of gate opening phenomena in that.

Two hybrid transition metal triphosphonates decorated with a tripodal imidazole ligand: synthesis, structures and properties

Two transition-metal triphosphonates with pillar-layered structures were synthesized and characterized. The luminescence, magnetic and proton conductive properties were investigated.

Sorption and sensing properties of coordination polymers with mixed 1,3,5-tri(1-imidazolyl)benzene and 2,6-naphthalenedicarboxylate ligands

Cd(ii) and Zn(ii) frameworks with mixed dicarboxylate and imidazole-containing ligands show selective adsorption and sensing properties.

Hydrogen Uptake by an Inclined Polycatenated Dynamic Metal-Organic Framework Based Material

A 2D + 2D → 3D inclined polycatenated dynamic metal-organic framework of {[Cu(4-bpe)(2-ntp)(H₂O)₂]·2H₂O}_n [1, where 2-ntp^2- = 2-nitroterephthalate and 4-bpe = 1,2-bis-(4-pyridyl)ethane] has been synthesized and characterized. The variable-temperature powder X-ray diffraction study indicates the dynamic nature of the inclined polycatenated framework, and the dehydrated framework with exposed metal centers exhibits excellent type I H₂ adsorption of 1.94 wt % at 77 K and 1 bar of pressure.

Solvent-dependent zinc(II) coordination polymers with mixed ligands: selective sorption and fluorescence sensing

Starting from the same metal salts and mixed organic ligands of 1,3,5-tris(1-imidazolyl)benzene (tib) and 2-bromo-1,4-benzenedicarboxylic acid (H2BDC-Br), two novel zinc(II) coordination polymers [Zn2(tib)2(BDC-Br)]2·2SO4·17H2O (1) and [Zn4(tib)2(BDC-Br)3(H2O)4SO4]·7.5H2O·2.5DMF (2) (DMF = N,N-dimethylformamide) were obtained by using different solvent systems of DMF/H2O and DMF/EtOH/H2O, respectively. 1 is an unusual (3,4)-connected 3D net with a Point symbol of {4·8·10(4)}{4·8·10}, while 2 is a complicated 1D chain, which is further connected to form a 3D supramolecular architecture by hydrogen bonding interactions. In particular, 1 and 2 exhibit selective adsorption of CO2 over N2 and show good selectivity for detection of acetone via fluorescence quenching.

Coordination assemblies of Zn(NO3)2 with 4-pyr-poly-2-ene and polycarboxylates: structural diversification and photoluminescence properties

Reactions of Zn(NO₃)₂·6H₂O with 4-pyr-poly-2-ene and five polycarboxylates afforded a series of coordination polymers with different architectures. Their thermal and photoluminescence properties were also investigated.

Functional group effects on structure and topology of cadmium(ii) frameworks with mixed organic ligands

Cadmium(ii) complexes were obtained by tuning functional groups of benzenedicarboxylate and reaction conditions, their ferroelectric and photoluminescence properties were studied.

Tuned synthesis of two coordination polymers of Cd(ii) using substituted bent 3-pyridyl linker and succinate: structures and their applications in anion exchange and sorption properties

Two new coordination polymers of Cd(ii) have been synthesized using disodium succinate and a substituted bent N,N'-donor ligand where the substitution on N,N'-donor ligand controlled the formation of the product.

Structures and properties of coordination polymers involving asymmetric biphenyl-3,2′,5′-tricarboxylate

The conformation stability and coordination modes of an asymmetric polycarboxylate ligand (H₃bptc) and the properties of its compounds have been investigated.