Selective and Multicyclic CO2 Adsorption with Visible Light-Driven Photodegradation of Organic Dyes in a Robust Metal-Organic Framework Embracing Heteroatom-Affixed Pores

Pore environment modulation with polarizing groups is one of the essential prerequisites for selective carbon dioxide (CO₂) adsorption in metal-organic frameworks (MOFs), wherein judicious installation of the photocatalytic feature can promise visible light-triggered degradation of toxic organic dye molecules. However, astute amalgamation of both these attributes over a single MOF is rather rare, yet much anticipated in view of sustainable applications. Pore engineering is effectively harnessed in a Zn(II)-based three-dimensional (3D) MOF, CSMCRI-16 (CSMCRI = Central Salt and Marine Chemicals Research Institute), through mixed-ligand assembly of a N-rich linker (L), 4,4'-oxybis(benzoic acid) (H₂oba) ligand, and [Zn₂(CO₂)₄N₂] paddle-wheel secondary building units (SBUs). The noninterpenetrated structure contains unbound nitrogen and accessible oxygen atom-decorated porous channels and exhibits admirable stability in diverse organic solvents, open air, and at elevated temperatures. The heteroatom-decorated porous channels facilitated excellent CO₂ uptake in the activated MOF (16a) with high selectivity over N₂ (CO₂/N₂: 155.3) at 273 K. The framework further exhibits reasonable CO₂ affinity and multicyclic CO₂ sorption recurrence without a significant loss in the uptake capacity. Benefitting from the presence of the [Zn₂(CO₂)₄N₂] cluster in conjugation with π-conjugated organic ligands, the extended 3D network revealed an optical band gap energy of 2.55 eV, which makes the MOF an efficient photocatalyst toward the degradation of the cationic dyes crystal violet (CV) and methylene blue (MB) in the presence of a simple 40 W visible light lamp without any assistance of external oxidants. The catalyst exhibits multicyclic performance and short reaction time in addition to the fact that catalytic efficiencies (CV: 97.2%, MB: 97.8%) are comparable to those of contemporary materials.

Assembly, photocatalytic and fluorescence properties of three new coordination complexes of zinc(II) and nickel(II) with two kinds of flexible bis(pyridyl)-bis(amide) ligands

Three new coordination complexes [Zn(btec)0.5(L1)0.5(H2O)] n (1), [Ni(H2btec)(L1)(H2O)2] n (2), and {[Ni(btec)0.5(L2)(H2O)3]·2H2O} n (3) [H4btec = 1,2,4,5-benzenetetracarboxylic acid), L1 = N,N′-bis(3-pyridyl)adipamide, L2 = N,N′-bis(3-pyridyl)octanediamide] have been obtained under hydrothermal conditions. Single-crystal X-ray diffraction analysis has revealed that complex 1 has a layer structure based on [Zn(btec)0.5] n ribbons and the μ 2-bridging ligands L 1 . Complex 2 possesses a layered framework constructed by [Ni(H2btec)] n linear chains and [Ni(L1)] n wave-like chains. Complex 3 forms layers based on [Ni(L2)] n helical chains and μ 2-bridging L2 ligands, representing an interesting 4-fold interpenetrating 2D braided framework. The three different 2D frameworks exhibit 3,4-connected {4.62}2{42.62.82} topology for 1, 4-connected {44.62} topology for 2 and 3-connected {63} topology for 3. Their adjacent layers are further linked by hydrogen bonding interactions to generate 3D supramolecular structures. The differences in the nature of both the metal ions and the organic ligands lead to various coordination modes in the final structures. The photocatalytic activities and the fluorescence properties of complexes 1–3 were investigated.

Hydrogen and Halogen Bond Mediated Coordination Polymers of Chloro-Substituted Pyrazin-2-Amine Copper(I) Bromide Complexes

A new class of six mono- (1; 3-Cl-, 2; 5-Cl-, 3; 6-Cl-) and di-(4; 3,6-Cl, 5; 5,6-Cl-, 6; 3,5-Cl-) chloro-substituted pyrazin-2-amine ligands (1–6) form complexes with copper (I) bromide, to give 1D and 2D coordination polymers through a combination of halogen and hydrogen bonding that were characterized by X-ray diffraction analysis. These Cu(I) complexes were prepared indirectly from the ligands and CuBr2 via an in situ redox process in moderate to high yields. Four of the pyrazine ligands, 1, 4–6 were found to favor a monodentate mode of coordination to one CuI ion. The absence of a C6-chloro substituent in ligands 1, 2 and 6 supported N1–Cu coordination over the alternative N4–Cu coordination mode evidenced for ligands 4 and 5. These monodentate systems afforded predominantly hydrogen bond (HB) networks containing a catenated (μ3-bromo)-CuI ‘staircase’ motif, with a network of ‘cooperative’ halogen bonds (XB), leading to infinite polymeric structures. Alternatively, ligands 2 and 3 preferred a μ2-N,N’ bridging mode leading to three different polymeric structures. These adopt the (μ3-bromo)-CuI ‘staircase’ motif observed in the monodentate ligands, a unique single (μ2-bromo)-CuI chain, or a discrete Cu2Br2 rhomboid (μ2-bromo)-CuI dimer. Two main HB patterns afforded by self-complimentary dimerization of the amino pyrazines described by the graph set notation R22(8) and non-cyclic intermolecular N–H∙∙∙N’ or N–H∙∙∙Br–Cu leading to infinite polymeric structures are discussed. The cooperative halogen bonding between C–Cl∙∙∙Cl–C and the C–Cl∙∙∙Br–Cu XB contacts are less than the sum of the van der Waals radii of participating atoms, with the latter ranging from 3.4178(14) to 3.582(15) Å. In all cases, the mode of coordination and pyrazine ring substituents affect the pattern of HBs and XBs in these supramolecular structures.

Structural diversity and modification in Ni(ii) coordination polymers: a peculiar phenomenon of reversible structural transformation between a 1D ladder and 2D layer

The coordination of 5-tert-IPA²⁻ ligands, the relaxation of the interdigitated 2D net and the breaking and connecting of the bis-pyridyl-bis-amide ligand demonstrate the peculiar reversible structural transformation between a 1D ladder and 2D layer.

Building coordination polymers using dipyridone ligands

Structural determination of the self-assemblies of 1H,1′H-[3,3′]bipyridinyl-6,6′-dione and its coordination chemistry with cobalt ions forming a novel coordination polymer.

A novel cadmium metal–organic framework-based multiresponsive fluorescent sensor demonstrating outstanding sensitivities and selectivities for detecting NB, Fe3+ ions and Cr2O72− anions

A Cd(ii) metal–organic framework (MOF) [Cd₃(L)(NTB)₂(DMA)₂]·2DMA was solvothermal prepared in the presence of ligand L (L = (E)-4,4′-(ethene-1,2-diyl)bis[(N-pyridin-3-yl)benzamide]) and ligand H₃NTB (H₃NTB = 4,4′,4′′-nitrilotribenzoic acid).

Metal/Carboxylate-Induced Versatile Structures of Nine 0D → 3D Complexes with Different Fluorescent and Electrochemical Behaviors

To investigate the effect of the polycarboxylates and metal ions on the assembly and structures of complexes based on a thiophene-containing bis-pyridyl-bis-amide N,N'-bis(pyridine-3-yl)thiophene-2,5-dicarboxamide (3-bptpa) ligand, nine 0D → 3D complexes of [Ni₂(3-bptpa)₄(1,2-BDC)₂(H₂O)₂] (1), [Ni(3-bptpa)(IP)(H₂O)₂]·H₂O (2), [Ni(3-bptpa)(5-MIP)(H₂O)₂]·H₂O (3), [Ni(3-bptpa)(5-NIP)(H₂O)] (4), [Ni(3-bptpa)(5-AIP)]·2H₂O (5), [Ni₂(OH)(3-bptpa)(1,3,5-BTC)]·DMA·5H₂O (6), [Cu(3-bptpa)(5-MIP)]·3H₂O (7), [Cu(3-bptpa)(5-AIP)(H₂O)_0.25]·H₂O (8), and [Cu(3-bptpa)(1,3,5-HBTC)] (9) (1,2-H₂BDC = 1,2-benzenedicarboxylic acid, H₂IP = 1,3-benzenedicarboxylic acid, 5-H₂MIP = 5-methylisophthalic acid, 5-H₂NIP = 5-nitroisophthalic acid, 5-H₂AIP = 5-aminoisophthalic acid, DMA = N,N'-dimethylacetamide, and 1,3,5-H₃BTC = 1,3,5-benzenetricarboxylic acid) have been hydrothermally/solvothermally synthesized and structurally characterized by IR, thermogravimetric, powder X-ray diffraction, and single-crystal X-ray diffraction. Complex 1 is a zero-dimensional (0D) bimetallic complex. Complexes 2 and 3 feature two similar one-dimensional ladderlike structures. Complex 4 displays a two-dimensional (2D) 4-connected network based on single-metallic nodes. Complex 5 shows a 2D double-layer structure containing a pair of 6³ [Ni(5-AIP)] honeycomblike sheets. Complex 6 is a 3,5-connected three-dimensional (3D) framework derived from bimetallic nodes and 6³ [Ni₂(OH)(1,3,5-BTC)] honeycomblike sheets. Complex 7 displays a 2D 4-connected grid based on bimetallic nodes. Complex 8 features a 2D double-layer structure based on two 4-connected [Cu(3-bptpa)(5-AIP)] sheets and bridging coordinated water molecules. Complex 9 is a 2D structure extended by incomplete deprotonation of 1,3,5-HBTC and 3-bptpa linkers. The effect of the metal ions and polycarboxylates on the structures of the title complexes was discussed, and the fluorescent properties of 1-9 were investigated. The carbon paste electrodes bulk-modified by complexes 3, 5, and 6-9 show different electrocatalytic activities for the oxidation of ascorbic acid as well as the reduction of hydrogen peroxide, nitrites, and bromates.

Versatile carboxylate-directed structures of ten 1D → 3D Ni(ii) coordination polymers: fluorescence behaviors and electrochemical activities

Ten 1D → 3D Ni(ii) coordination polymers based on a phenyl/methylene-mixed-bridged ligand have been obtained and structurally directed by carboxylates; they show different fluorescence behaviors and electrochemical activities.

Crystal-to-crystal transformation and linker exchange in Cd(ii) coordination polymers based on flexible bis-pyridyl-bis-amide and 1,4-naphthalenedicarboxylate

Solvothermal reactions of Cd(ii) salts and naphthalene-1,4-dicarboxylic acid with bis(N-pyrid-3-ylmethyl)adipoamide and bis(N-pyrid-3-ylmethyl)suberoamide yield three Cd(ii) coordination polymers that undergo reversible crystal-to-crystal transformation and linker exchange.

Structural Diversity of Six Coordination Polymers Based on the Designed X-Shaped Ligand 1,1,1,1-Tetrakis[(3-pyridiniourea)methyl]methane

In this study, six coordination polymers (CPs), {[Ag₂(L)(CF₃SO₃)]·CF₃SO₃·2H₂O·DMF}_n (1), {[Ag(L)]·SbF₆·4DMF·H₂O}_n (2), {[Zn(L)_0.5(I)₂]·3.75H₂O}_n (3), {[Cd₂(L)(I)₄(H₂O)(DMF)]·4H₂O·3DMF}_n (4), {[Hg₂(L)(I)₄]·H₂O·4DMF}_n (5) and {[Hg₂(L)(Cl)₄]·2H₂O·3DMF}_n (6), were obtained based on the designed X-shaped urea-based ligand. X-ray single crystal diffraction analysis revealed that complex 1 displayed a 3D (3,4)-connected {6·8²}{6⁴·8²}-tcj net. Complex 2 featured a 2D 4-connected {4³·6³} sheet. Complexes 3 and 5 exhibited a 1D polymeric loop chain. Complex 4 displayed a 1D polymeric fishbone chain. Complex 6 showed a 2D 4-connected {4⁴·6²}-sql sheet. Structural comparison revealed that not only the metal ions, but also the anions played crucial roles in the control of final structures.

Tuning structures and emissive properties in a series of Zn(ii) and Cd(ii) coordination polymers containing dicarboxylic acids and nicotinamide pillars

The influence of the metal, ligand, and solvent on structures and emission properties was monitored.

Polycarboxylate-directed semi-rigid pyridyl-amide-based various NiII complexes: electrochemical properties and enhancements of photocatalytic activities by calcination

Four different pyridyl-amide-based Ni-complexes were synthesized by tuning polycarboxylates, displaying bifunctional electrocatalytic properties and enhancements of photocatalytic activities by calcination.

Cooperative effects of metal cations and coordination modes on luminescent s-block metal–organic complexes constructed from V-shaped 4,4′-sulfonyldiphenol

Thirteen s-block metal–organic complexes with different supramolecular networks arising from the coordination modes of the ligands and properties of the metal cations have been synthesized and exhibit violet and blue luminescence in the solid state at room temperature.

Metal and Ligand Effects on the Construction of Divalent Coordination Polymers Based on bis-Pyridyl-bis-amide and Polycarboxylate Ligands

Ten coordination polymers constructed from divalent metal salts, polycarboxylic acids, and bis-pyridyl-bis-amide ligands with different donor atom positions and flexibility are reported. They were structurally characterized by single-crystal X-ray diffraction. The ten coordination polymers are as follows: (1) {[Ni(L¹)(3,5-PDA)(H₂O)₃]·2H₂O}_n (L¹ = N,N′-di(3-pyridyl)suberoamide, 3,5-H₂PDA = 3,5-pyridinedicarboxylic acid); (2) {[Ni₂(L¹)₂(1,3,5-HBTC)₂(H₂O)₄]·H₂O}_n (1,3,5-H₃BTC = 1,3,5-benzenetricarboxylic acid); (3) {[Ni(L²)(5-tert-IPA)(H₂O)₂]·2H₂O}_n (L² = N,N′-di(3-pyridyl)adipoamide, 5-tert-H₂IPA = 5-tert-butylisophthalic acid); (4) [Ni(L³)_1.5(5-tert-IPA)]_n (L³ = N,N′-di(4-pyridyl)adipoamide); (5) [Co(L¹)(1,3,5-HBTC)(H₂O)]_n; (6) {[Co₃(L¹)₃(1,3,5-BTC)₂(H₂O)₂]·6H₂O}_n; (7) [Cu(L⁴)(AIPA)]_n (L⁴ = N,N′-bis(3-pyridinyl)terephthalamide, H₂AIPA = 5-acetamido isophthalic acid); (8) {[Cu(L²)_0.5(AIPA)]·MeOH}_n; (9) {[Zn(L⁴)(AIPA)]·2H₂O}_n; and (10) {[Zn(L²)(AIPA)]·2H₂O}_n. Complex 1 forms a 1D chain and 2 is a two-fold interpenetrated 2D layer with the sql topology, while 3 is a 2D layer with the hcp topology and 4 shows a self-catenated 3D framework with the rare (4²·6⁷·8)-hxg-d-5-C2/c topology. Different Co/1,3,5-H₃BTC ratios were used to prepare 5 and 6, affording a 2D layer with the sql topology and a 2D layer with the (4·8⁵)₂(4)₂(8³)₂(8) topology that can be further simplified to an hcp topology. While complex 7 is a 2D layer with the (4²·6⁷·8)(4²·6)-3,5L2 topology and 8 is a 2-fold interpenetrated 3D framework with the pcu topology, complexes 9 and 10 are self-catenated 3D frameworks with the (4²⁴·6⁴)-8T2 and the (4⁴·6¹⁰·8)-mab topologies, respectively. The effects of the identity of the metal center, the ligand isomerism, and the flexibility of the spacer ligands on the structural diversity of these divalent coordination polymers are discussed. The luminescent properties of 9 and 10 and their photocatalytic effects on the degradation of dyes are also investigated.

A platinum(ii)–palladium(ii)–nickel(ii) heterotrimetallic coordination polymer showing a cooperative effect on catalytic hydrogen evolution

Stepwise construction of a 1D heterotrimetallic coordination polymer containing all three group 10 metal ions and its heterogeneous catalytic activity for electrochemical hydrogen evolution are reported.

Charge Localisation in Heavy Alkali Metal Ion Complexes of 4,4'-Biphenyldicarboxylate

Crystal structure determinations on the isomorphous RbI and CsI complexes of 4,4′-biphenyldicarboxylate have shown the carboxylate entities to be coordinated in an unusual fashion where both oxygen atoms are in a tetrahedral environment indicative of negative charge localisation on each. The metal ions also show a highly irregular form of six-coordination, while the biphenyl units are planar, seemingly as a result of attractive interactions between the ortho hydrogen atoms.

Polycarboxylate-directed various Co(ii) complexes based on a “V”-like bis-pyridyl-bis-amide derivative: construction, electrochemical and photocatalytic properties

Six Co(ii) complexes have been hydrothermally synthesized with mixed ligands. The effects of the polycarboxylates on the structures of the title complexes have been discussed.

Experimental and theoretical study of photoluminescence and magnetic properties of metal–organic polymers based on squarate and tetrazolate moieties containing linkers

Cd²⁺, Zn²⁺ or Co²⁺ based luminescence and magnetic properties of isostructural metal organic chains.