Effects of two benzenedicarboxylic acids on the construction of CdII coordination polymers incorporating a flexible N‐donor ligand

Compared with the monomorphic type of ligand, combining mixed ligands in one coordination polymer offers greater tunability of the structural framework. Employment of N‐heterocyclic ligands and aromatic polycarboxylates is an effective approach for the construction of metal–organic frameworks (MOFs). Two new coordination polymers incorporating both 2‐[(1H‐imidazol‐1‐yl)methyl]‐1H‐benzimidazole (imb) and benzenedicarboxylic acid isomers, namely, catena‐poly[[[di‐μ‐chlorido‐bis[(2‐carboxybenzoato‐κ²O¹,O^1′)cadmium(II)]]‐bis{μ‐2‐[(1H‐imidazol‐1‐yl)methyl]‐1H‐benzimidazole‐κ²N:N′}] dihydrate], {[Cd(C₈H₅O₄)Cl(C₁₁H₁₀N₄)]·H₂O}_n, (I), and poly[[aqua(μ₂‐benzene‐1,3‐dicarboxylato‐κ³O¹,O^1′:O³){μ₂‐2‐[(1H‐imidazol‐1‐yl)methyl]‐1H‐benzimidazole‐κ²N:N′}cadmium(II)] dihydrate], {[Cd(C₈H₄O₄)(C₁₁H₁₀N₄)(H₂O)]·2H₂O}_n, (II), have been prepared and structurally characterized by single‐crystal X‐ray diffraction. In polymer (I), imb ligands bridge Cd^II ions, forming a one‐dimensional chain, and 2‐carboxybenzoate anions coordinate to the Cd^II ions in a terminal fashion. Polymer (II) exhibits a two‐dimensional network structure in which imb ligands and the benzene‐1,3‐dicarboxylate anions join Cd^II ions co‐operatively. This indicates that changing of the aromatic dicarboxylic acids can result in polymers with different compositions and architectures. Moreover, their IR spectra, PXRD (powder X‐ray diffraction) patterns, thermogravimetric analyses and fluorescence properties were also investigated.     

A new one‐dimensional CdII coordination polymer with a two‐dimensional layered structure incorporating 2‐[(1H‐imidazol‐1‐yl)methyl]‐1H‐benzimidazole and benzene‐1,2‐dicarboxylate ligands

The N‐heterocyclic ligand 2‐[(1H‐imidazol‐1‐yl)methyl]‐1H‐benzimidazole (imb) has a rich variety of coordination modes and can lead to polymers with intriguing structures and interesting properties. In the coordination polymer catena‐poly[[cadmium(II)‐bis[μ‐benzene‐1,2‐dicarboxylato‐κ⁴O¹,O^1′:O²,O^2′]‐cadmium(II)‐bis{μ‐2‐[(1H‐imidazol‐1‐yl)methyl]‐1H‐benzimidazole}‐κ²N²:N³;κ²N³:N²] dimethylformamide disolvate], {[Cd(C₈H₄O₄)(C₁₁H₁₀N₄)]·C₃H₇NO}_n, (I), each Cd^II ion exhibits an irregular octahedral CdO₄N₂ coordination geometry and is coordinated by four O atoms from two symmetry‐related benzene‐1,2‐dicarboxylate (1,2‐bdic²⁻) ligands and two N atoms from two symmetry‐related imb ligands. Two Cd^II ions are connected by two benzene‐1,2‐dicarboxylate ligands to generate a binuclear [Cd₂(1,2‐bdic)₂] unit. The binuclear units are further connected into a one‐dimensional chain by pairs of bridging imb ligands. These one‐dimensional chains are further connected through N—H…O hydrogen bonds and π–π interactions, leading to a two‐dimensional layered structure. The dimethylformamide solvent molecules are organized in dimeric pairs via weak interactions. In addition, the title polymer exhibits good fluorescence properties in the solid state at room temperature.     

An unusual partial occupancy of labile chloride and aqua ligands in cocrystallized isomers of a nickel(II) complex bearing a tripodal N4‐donor ligand

A novel Ni²⁺ complex with the N₄‐donor tripodal ligand bis[(1‐methyl‐1H‐imidazol‐2‐yl)methyl][2‐(pyridin‐2‐yl)ethyl]amine (L), namely, aqua{bis[(1‐methyl‐1H‐imidazol‐2‐yl‐κN³)methyl][2‐(pyridin‐2‐yl‐κN)ethyl]amine‐κN}chloridonickel(II) perchlorate, [NiCl(C₁₇H₂₂N₆)(H₂O)]ClO₄ or [NiCl(H₂O)(L)Cl]ClO₄ ( 1 ), was synthesized and characterized by spectroscopic and spectrometric methods. The crystal structure of 1 reveals an interesting and unusual cocrystallization of isomeric complexes, which are crystallographically disordered with partial occupancy of the labile cis aqua and chloride ligands. The Ni²⁺ centre exhibits a distorted octahedral environment, with similar bond lengths for the two Ni—N(imidazole) bonds. The bond length increases for Ni—N(pyridine) and Ni—N(amine), which is in agreement with literature examples. The bond lengths of the disordered labile sites are also in the expected range and the Ni—Cl and Ni—O bond lengths are comparable with similar compounds. The electronic, redox and solution stability behaviour of 1 were also evaluated, and the data obtained suggest the maintenance of structural integrity, with no sign of demetalation or decomposition under the studied conditions.     

In situ synthesis of mononuclear copper(II) complexes of the new tridentate ligand bis[(3,5‐dimethyl‐1H‐pyrazol‐1‐yl)methyl]amine

Two mononuclear copper complexes, {bis[(3,5‐dimethyl‐1H‐pyrazol‐1‐yl‐κN²)methyl]amine‐κN}(3,5‐dimethyl‐1H‐pyrazole‐κN²)(perchlorato‐κO)copper(II) perchlorate, [Cu(ClO₄)(C₅H₈N₂)(C₁₂H₁₉N₅)]ClO₄, (I), and {bis[(3,5‐dimethyl‐1H‐pyrazol‐1‐yl‐κN²)methyl]amine‐κN}bis(3,5‐dimethyl‐1H‐pyrazole‐κN²)copper(II) bis(hexafluoridophosphate), [Cu(C₅H₈N₂)₂(C₁₂H₁₉N₅)](PF₆)₂, (II), have been synthesized by the reactions of different copper salts with the tripodal ligand tris[(3,5‐dimethyl‐1H‐pyrazol‐1‐yl)methyl]amine (TDPA) in acetone–water solutions at room temperature. Single‐crystal X‐ray diffraction analysis revealed that they contain the new tridentate ligand bis[(3,5‐dimethyl‐1H‐pyrazol‐1‐yl)methyl]amine (BDPA), which cannot be obtained by normal organic reactions and has thus been captured in the solid state by in situ synthesis. The coordination of the Cu^II ion is distorted square pyramidal in (I) and distorted trigonal bipyramidal in (II). The new in situ generated tridentate BDPA ligand can act as a meridional or facial ligand during the process of coordination. The crystal structures of these two compounds are stabilized by classical hydrogen bonding as well as intricate nonclassical hydrogen‐bond interactions.     

3D semiconducting Co–MOFs based on 5‐(hydroxymethyl)isophthalic acid and imidazole derivatives: syntheses and crystal structures

Two three‐dimensional cobalt‐based metal–organic frameworks with 5‐(hydroxymethyl)isophthalic acid (H₂HIPA), namely poly[[μ₂‐1,4‐bis(2‐methyl‐1H‐imidazol‐1‐yl)benzene‐κ²N³:N^3′][μ₂‐5‐(hydroxymethyl)isophthalato‐κ²O¹:O³]cobalt(II)], [Co(C₉H₆O₅)(C₁₄H₁₄N₄)]_n ( 1 ), and poly[tris[μ₂‐1,4‐bis(1H‐imidazol‐1‐yl)benzene‐κ²N³:N^3′]bis[μ₃‐5‐(hydroxymethyl)isophthalato‐κ²O¹:O³:O⁵]dicobalt(II)], [Co₂(C₉H₆O₅)₂(C₁₂H₁₀N₄)₃]_n ( 2 ), were synthesized under similar hydrothermal conditions. Single‐crystal X‐ray diffraction analyses revealed that 5‐(hydroxymethyl)isophthalate (HIPA^2?) and 1,4‐bis(2‐methyl‐1H‐imidazol‐1‐yl)benzene (1,4‐BMIB) are simple linkers connecting cobalt centres to build a fourfold interpenetration dia framework in complex 1 . However, complex 2 is a pillared‐layer framework with a (3,6)‐connected network constructed by 1,4‐bis(1H‐imidazol‐1‐yl)benzene (1,4‐DIB) linkers, 3‐connected HIPA^2? ligands and 6‐connected Co^II centres. The above significant structural differences can be ascribed to the introduction of the different auxiliary N‐donor ligands. Moreover, UV–Vis spectroscopy and Mott–Schottky measurements confirmed that complexes 1 and 2 are typical n‐type semiconductors.     

Three AgI,CuI and CdII coordination polymers based on the new asymmetrical ligand 2‐{4‐[(1H‐imidazol‐1‐yl)methyl]phenyl}‐5‐(pyridin‐4‐yl)‐1,3,4‐oxadiazole: syntheses,characterization and emission properties

The new asymmetrical organic ligand 2‐{4‐[(1H‐imidazol‐1‐yl)methyl]phenyl}‐5‐(pyridin‐4‐yl)‐1,3,4‐oxadiazole ( L , C₁₇H₁₃N₅O), containing pyridine and imidazole terminal groups, as well as potential oxdiazole coordination sites, was designed and synthesized. The coordination chemistry of L with soft Ag^I, Cu^I and Cd^II metal ions was investigated and three new coordination polymers (CPs), namely, catena‐poly[[silver(I)‐μ‐2‐{4‐[(1H‐imidazol‐1‐yl)methyl]phenyl}‐5‐(pyridin‐4‐yl)‐1,3,4‐oxadiazole] hexafluoridophosphate], {[Ag( L )]PF₆}_n, catena‐poly[[copper(I)‐di‐μ‐iodido‐copper(I)‐bis(μ‐2‐{4‐[(1H‐imidazol‐1‐yl)methyl]phenyl}‐5‐(pyridin‐4‐yl)‐1,3,4‐oxadiazole)] 1,4‐dioxane monosolvate], {[Cu₂I₂( L )₂]·C₄H₈O₂}_n, and catena‐poly[[[dinitratocopper(II)]‐bis(μ‐2‐{4‐[(1H‐imidazol‐1‐yl)methyl]phenyl}‐5‐(pyridin‐4‐yl)‐1,3,4‐oxadiazole)]–methanol–water (1/1/0.65)], {[Cd( L )₂(NO₃)₂]·2CH₄O·0.65H₂O}_n, were obtained. The experimental results show that ligand L coordinates easily with linear Ag^I, tetrahedral Cu^I and octahedral Cd^II metal atoms to form one‐dimensional polymeric structures. The intermediate oxadiazole ring does not participate in the coordination interactions with the metal ions. In all three CPs, weak π–π interactions between the nearly coplanar pyridine, oxadiazole and benzene rings play an important role in the packing of the polymeric chains.     

Four NiII complexes with the new cyclam–methylimidazole ligand 1‐[(1‐methyl‐1H‐imidazol‐2‐yl)methyl]‐1,4,8,11‐tetraazacyclotetradecane

Although it has not proved possible to crystallize the newly prepared cyclam–methylimidazole ligand 1‐[(1‐methyl‐1H‐imidazol‐2‐yl)methyl]‐1,4,8,11‐tetraazacyclotetradecane (L^Im1), the trans and cis isomers of an Ni^II complex, namely trans‐aqua{1‐[(1‐methyl‐1H‐imidazol‐2‐yl)methyl]‐1,4,8,11‐tetraazacyclotetradecane}nickel(II) bis(perchlorate) monohydrate, [Ni(C₁₅H₃₀N₆)(H₂O)](ClO₄)₂·H₂O, (1), and cis‐aqua{1‐[(1‐methyl‐1H‐imidazol‐2‐yl)methyl]‐1,4,8,11‐tetraazacyclotetradecane}nickel(II) bis(perchlorate), [Ni(C₁₅H₃₀N₆)(H₂O)](ClO₄)₂, (2), have been prepared and structurally characterized. At different stages of the crystallization and thermal treatment from which (1) and (2) were obtained, a further two compounds were isolated in crystalline form and their structures also analysed, namely trans‐{1‐[(1‐methyl‐1H‐imidazol‐2‐yl)methyl]‐1,4,8,11‐tetraazacyclotetradecane}(perchlorato)nickel(II) perchlorate, [Ni(ClO₄)(C₁₅H₃₀N₆)]ClO₄, (3), and cis‐{1,8‐bis[(1‐methyl‐1H‐imidazol‐2‐yl)methyl]‐1,4,8,11‐tetraazacyclotetradecane}nickel(II) bis(perchlorate) 0.24‐hydrate, [Ni(C₂₀H₃₆N₆)](ClO₄)₂·0.24H₂O, (4); the 1,8‐bis[(1‐methyl‐1H‐imidazol‐2‐yl)methyl]‐1,4,8,11‐tetraazacyclotetradecane ligand is a minor side product, probably formed in trace amounts in the synthesis of L^Im1. The configurations of the cyclam macrocycles in the complexes have been analysed and the structures are compared with analogues from the literature.     

A triangular palladium(II) supramolecular coordination complex based on 1,4‐bis(1H‐imidazol‐1‐yl)benzene and (2,2′‐bipyridyl)palladium(II) nitrate: synthesis and crystal structure

The self‐assembly of ditopic bis(1H‐imidazol‐1‐yl)benzene ligands ( L ^H) and the complex (2,2′‐bipyridyl‐κ²N,N′)bis(nitrato‐κO)palladium(II) affords the supramolecular coordination complex tris[μ‐bis(1H‐imidazol‐1‐yl)benzene‐κ²N³:N^3′]‐triangulo‐tris[(2,2′‐bipyridyl‐κ²N,N′)palladium(II)] hexakis(hexafluoridophosphate) acetonitrile heptasolvate, [Pd₃(C₁₀H₈N₂)₃(C₁₂H₁₀N₄)₃](PF₆)₆·7CH₃CN, 2 . The structure of 2 was characterized in acetonitrile‐d₃ by ¹H/¹³C NMR spectroscopy and a DOSY experiment. The trimeric nature of supramolecular coordination complex 2 in solution was ascertained by cold spray ionization mass spectrometry (CSI–MS) and confirmed in the solid state by X‐ray structure analysis. The asymmetric unit of 2 comprises the trimetallic Pd complex, six PF₆^? counter‐ions and seven acetonitrile solvent molecules. Moreover, there is one cavity within the unit cell which could contain diethyl ether solvent molecules, as suggested by the crystallization process. The packing is stabilized by weak inter‐ and intramolecular C—H…N and C—H…F interactions. Interestingly, the crystal structure displays two distinct conformations for the L ^H ligand (i.e. syn and anti), with an all‐syn‐[Pd] coordination mode. This result is in contrast to the solution behaviour, where multiple structures with syn/anti‐ L ^H and syn/anti‐[Pd] are a priori possible and expected to be in rapid equilibrium.     

Complexation du 2‐[(5‐méthyl­pyrazolyl)méthyle]benzimidazole par les chlorures de cuivre et de cadmium

The structures of dichloro{2‐[(5‐methyl‐1H‐pyrazol‐3‐yl‐κN²)methyl]‐1H‐1,3‐benzimidazole‐κN³}copper(II), [CuCl₂(C₁₂H₁₂N₄)], and di‐μ‐chloro‐bis(chloro{2‐[(5‐methyl‐1H‐pyrazol‐3‐yl‐κN²)methyl]‐1H‐1,3‐benzimidazole‐κN³}­cadmium(II)), [Cd₂Cl₄(C₁₂H₁₂N₄)₂], show that these compounds have the structural formula [ML(Cl)₂]_n, where L is 2‐[(5‐methylpyra­zolyl)methyl]benzimidazole. When M is copper, the complex is a monomer (n = 1), with a tetrahedral coordination for the Cu atom. When M is cadmium (n = 2), the complex lies about an inversion centre giving rise to a centrosymmetric dimer in which the Cd atoms are bridged by two chloride ions and are pentacoordinated.     

A twofold interpenetrating two‐dimensional zinc(II) coordination polymer: synthesis,crystal structure and physical properties

A novel twofold interpenetrating two‐dimensional (2D) Zn^II coordination framework, poly[[(μ‐1,3‐bis(2‐methyl‐1H‐imidazol‐1‐yl)benzene‐κ²N³:N³)(μ‐naphthalene‐2,6‐dicarboxylato‐κ²O²:O⁶)zinc(II)] dimethylformamide monosolvate], {[Zn(C₁₂H₆O₄)(C₁₄H₁₄N₄)]·C₃H₇NO}_n or {[Zn(1,3‐BMIB)(NDC)]·DMF}_n (I), where H₂NDC is naphthalene‐2,6‐dicarboxylic acid, 1,3‐BMIB is 1,3‐bis(2‐methyl‐1H‐imidazol‐1‐yl)benzene and DMF is dimethylformamide, was prepared and characterized through IR spectroscopy, elemental analysis, thermal analysis and single‐crystal X‐ray diffraction. Single‐crystal X‐ray diffraction analysis revealed that (I) exhibits an unusual twofold interpenetrating 2D network. In addition, it displays strong fluorescence emissions and a high photocatalytic activity for the degradation of Rhodamine B (RhB) under UV‐light irradiation.     

Two nickel(II) bis[(pyridin‐2‐yl)methyl]amine complexes with homophthalic and benzene‐1,2,4,5‐tetracarboxylic acids

Two new Ni^II complexes involving the ancillary ligand bis[(pyridin‐2‐yl)methyl]amine (bpma) and two different carboxylate ligands, i.e. homophthalate [hph; systematic name: 2‐(2‐carboxylatophenyl)acetate] and benzene‐1,2,4,5‐tetracarboxylate (btc), namely catena‐poly[[aqua{bis[(pyridin‐2‐yl)methyl]amine‐κ³N,N′,N′′}nickel(II)]‐μ‐2‐(2‐carboxylatophenyl)aceteto‐κ²O:O′], [Ni(C₉H₆O₄)(C₁₂H₁₃N₃)(H₂O)]_n, and (μ‐benzene‐1,2,4,5‐tetracarboxylato‐κ⁴O¹,O²:O⁴,O⁵)bis(aqua{bis[(pyridin‐2‐yl)methyl]amine‐κ³N,N′,N′′}nickel(II)) bis(triaqua{bis[(pyridin‐2‐yl)methyl]amine‐κ³N,N′,N′′}nickel(II)) benzene‐1,2,4,5‐tetracarboxylate hexahydrate, [Ni₂(C₁₀H₂O₈)(C₁₂H₁₃N₃)₂(H₂O)₂]·[Ni(C₁₂H₁₃N₃)(H₂O)₃]₂(C₁₀H₂O₈)·6H₂O, (II), are presented. Compound (I) is a one‐dimensional polymer with hph acting as a bridging ligand and with the chains linked by weak C—H...O interactions. The structure of compound (II) is much more complex, with two independent Ni^II centres having different environments, one of them as part of centrosymmetric [Ni(bpma)(H₂O)]₂(btc) dinuclear complexes and the other in mononuclear [Ni(bpma)(H₂O)₃]²⁺ cations which (in a 2:1 ratio) provide charge balance for btc⁴⁻ anions. A profuse hydrogen‐bonding scheme, where both coordinated and crystal water molecules play a crucial role, provides the supramolecular linkage of the different groups.     

A new one‐dimensional ZnII coordination polymer based on 2‐[(1H‐imidazol‐1‐yl)methyl]‐1H‐benzimidazole and benzene‐1,2‐dicarboxylate

Multidentate N‐heterocyclic compounds form a variety of metal complexes with many intriguing structures and interesting properties. The title coordination polymer, catena‐poly[zinc(II)‐bis{μ‐2‐[(1H‐imidazol‐1‐yl)methyl]‐1H‐benzimidazole}‐κ²N³:N^3′;N^3′:N³‐zinc(II)‐bis(μ‐benzene‐1,2‐dicarboxylato)‐κ²O¹:O²;κ³O¹,O^1′:O²], [Zn₂(C₈H₄O₄)₂(C₁₁H₁₀N₄)₂]_n, has been synthesized by the reaction of Zn(NO₃)₂ with 2‐[(1H‐imidazol‐1‐yl)methyl]‐1H‐benzimidazole (imb) and benzene‐1,2‐dicarboxylic acid (H₂bdic) under hydrothermal conditions. There are two crystallographically distinct imb ligands [imb(A) and imb(B)] in the structure which adopt very similar coordination geometries. The imb(A) ligand bridges two symmetry‐related Zn1 ions, yielding a binuclear [(Zn1)₂{imb(A)}₂] unit, and the imb(B) ligand bridges two symmetry‐related Zn2 ions resulting in a binuclear [(Zn2)₂{imb(B)}₂] unit. The above‐mentioned binuclear units are further connected alternately by pairs of bridging bdic²⁻ ligands, forming an infinite one‐dimensional chain. These one‐dimensional chains are further connected through N—H...O hydrogen bonds, leading to a two‐dimensional layered structure. In addition, the title polymer exhibits good fluorescence properties in the solid state at room temperature.     

Band gap,sorption properties and fluorescence sensing behaviour of a novel 1D→2D cathenane‐like cobalt(II)–organic framework

A novel hydrolytic stable Co^II–organic framework, namely poly[[bis(2‐amino‐4‐sulfonatobenzoato‐κO¹)tetraaquatris{μ‐1,4‐bis[(imidazol‐1‐yl)methyl]benzene‐κ²N³:N^3′}dicobalt(II)] tetrahydrate], {[Co(C₇H₅NO₅S)(C₁₄H₁₄N₄)_1.5(H₂O)₂]·2H₂O}_n, ( 1 ), based on multifunctional 2‐amino‐5‐sulfobenzoic acid (H₂asba) and the auxiliary flexible ligand 1,4‐bis[(imidazol‐1‐yl)methyl]benzene (bix), was prepared using the solution evaporation method. The purity of ( 1 ) was confirmed by elemental analysis and powder X‐ray diffraction (PXRD) analysis. Complex ( 1 ) shows a novel 1D→2D interpenetrating network, which is further extended into a 3D supramolecular framework with channels occupied by the lattice water molecules. The 2‐amino‐4‐sulfonatobenzoate (asba^2?) ligand adopts a monodentate coordination mode. The bix ligands exhibit gauche–gauche (GG) and trans–trans (TT) conformations. A detailed analysis of the solid‐state diffuse‐reflectance UV–Vis spectrum reveals that an indirect band gap exists in the complex. The band structure, the total density of states (TDOS) and the partial density of states (PDOS) were calculated using the CASTEP program. The calculated band gap (E_g) matches well with the experimental one. The complex exhibits a reversible dehydration–rehydration behaviour. Interestingly, gas sorption experiments demonstrate that the new fully anhydrous compound obtained by activating complex ( 1 ) at 400 K shows selective adsorption of CO₂ over N₂. Complex ( 1 ) retains excellent framework stability in a variety of solvents and manifests distinct solvent‐dependent fluorescence properties. Moreover, the complex shows multiresponsive fluorescence sensing for some nitroaromatics in aqueous medium.     

Synthesis,structure, thermostability and luminescence properties of ZnII and CdII coordination polymers based on dimethysuccinate and flexible 1,4‐bis(imidazol‐1‐ylmethyl)benzene ligands

The design and synthesis of functional coordination polymers is motivated not only by their structural beauty but also by their potential applications. Zn^II and Cd^II coordination polymers are promising candidates for producing photoactive materials because these d¹⁰ metal ions not only possess a variety of coordination numbers and geometries, but also exhibit luminescence properties when bound to functional ligands. It is difficult to predict the final structure of such polymers because the assembly process is influenced by many subtle factors. Bis(imidazol‐1‐yl)‐substituted alkane/benzene molecules are good bridging ligands because their flexibility allows them to bend and rotate when they coordinate to metal centres. Two new Zn^II and Cd^II coordination polymers based on mixed ligands, namely, poly[[μ₂‐1,4‐bis(imidazol‐1‐ylmethyl)benzene‐κ²N³:N^3′]bis(μ₃‐2,2‐dimethylbutanoato‐κ³O¹:O⁴:O^4′)dizinc(II)], [Zn₂(C₆H₈O₄)₂(C₁₄H₁₄N₄)]_n, and poly[[μ₂‐1,4‐bis(imidazol‐1‐ylmethyl)benzene‐κ²N³:N^3′]bis(μ₃‐2,2‐dimethylbutanoato‐κ⁵O¹,O^1′:O⁴,O^4′:O⁴)dicadmium(II)], [Cd₂(C₆H₈O₄)₂(C₁₄H₁₄N₄)]_n, have been synthesized under hydrothermal conditions and characterized by single‐crystal X‐ray diffraction, elemental analysis, IR spectroscopy and thermogravimetric analysis. Both complexes crystallize in the monoclinic space group C2/c with similar unit‐cell parameters and feature two‐dimensional structures formed by the interconnection of S‐shaped Zn(Cd)–2,2‐dimethylsuccinate chains with 1,4‐bis(imidazol‐1‐ylmethyl)benzene bridges. However, the Cd^II and Zn^II centres have different coordination numbers and the 2,2‐dimethylsuccinate ligands display different coordination modes. Both complexes exhibit a blue photoluminescence in the solid state at room temperature.     

Synthesis,structure and properties of a new three‐dimensional interpenetrated metal–organic framework with 3,3′‐azodibenzoic acid (H2azdc) and 1,4‐bis(1H‐imidazol‐1‐yl)butane (bimb): {[Cd(azdc)(bimb)2]·H2O}n

A new three‐dimensional interpenetrated Cd^II–organic framework based on 3,3′‐azodibenzoic acid [3,3′‐(diazenediyl)dibenzoic acid, H₂azdc] and the auxiliary flexible ligand 1,4‐bis(1H‐imidazol‐1‐yl)butane (bimb), namely poly[[bis[μ₂‐1,4‐bis(1H‐imidazol‐1‐yl)butane‐κ²N³:N^3′][μ₂‐3,3′‐(diazenediyl)dibenzoato‐κ²O:O′]cadmium(II)] monohydrate], {[Cd(C₁₄H₈N₂O₄)(C₁₀H₁₄N₂)₂]·H₂O}_n, (1), was obtained by a typical solution reaction in mixed solvents (water and N,N′‐dimethylformamide). Each Cd^II centre is six‐coordinated by two O atoms of bis‐monodentate bridging carboxylate groups from two azdc²⁻ ligands and by four N atoms from four bimb ligands, forming an octahedral coordination environment. The Cd^II ions are connected by the bimb ligands, resulting in two‐dimensional (4,4) layers, which are further pillared by the azdc²⁻ ligands, affording a threefold interpenetrated three‐dimensional α‐Po topological framework with the Schläfli symbol 4¹²6³. The thermal stability and solid‐state fluorescence properties of (1) have been investigated.     

Two isomorphous ZnII/CoII complexes with tri‐tert‐butoxysilanethiol and histamine,and (4‐hydroxymethyl‐1H‐imidazole‐κN)bis(tri‐tert‐butoxysilanethiolato‐κ2O,S)zinc(II)

The complexes [2‐(1H‐imidazol‐4‐yl‐κN³)ethylamine‐κN]bis(tri‐tert‐butoxysilanethiolato‐κS)cobalt(II), [Co(C₁₂H₂₇O₃SSi)₂(C₅H₉N₃)], and [2‐(1H‐imidazol‐4‐yl‐κN³)ethylamine‐κN]bis(tri‐tert‐butoxysilanethiolato‐κS)zinc(II), [Zn(C₁₂H₂₇O₃SSi)₂(C₅H₉N₃)], are isomorphous. The central Zn^II/Co^II ions are surrounded by two S atoms from the tri‐tert‐butoxysilanethiolate ligand and by two N atoms from the chelating histamine ligand in a distorted tetrahedral geometry, with two intramolecular N—H...O hydrogen‐bonding interactions between the histamine NH₂ groups and tert‐butoxy O atoms. Molecules of the complexes are joined into dimers via two intermolecular bifurcated N—H...(S,O) hydrogen bonds. The Zn^II atom in [(1H‐imidazol‐4‐yl‐κN³)methanol]bis(tri‐tert‐butoxysilanethiolato‐κ²O,S)zinc(II), [Zn(C₁₂H₂₇O₃SSi)₂(C₄H₆N₂O)], is five‐coordinated by two O and two S atoms from the O,S‐chelating silanethiolate ligand and by one N atom from (1H‐imidazol‐4‐yl)methanol; the hydroxy group forms an intramolecular hydrogen bond with sulfur. Molecules of this complex pack as zigzag chains linked by N—H...O hydrogen bonds. These structures provide reference details for cysteine‐ and histidine‐ligated metal centers in proteins.     

A new three‐dimensional CdII supramolecular framework constructed from the 1‐[(1H‐tetrazol‐5‐yl)methyl]‐1,4‐diazoniabicyclo[2.2.2]octane ligand

A new tetrazole–metal supramolecular compound, di‐μ‐chlorido‐bis(trichlorido{1‐[(1H‐tetrazol‐5‐yl‐κN²)methyl]‐1,4‐diazoniabicyclo[2.2.2]octane}cadmium(II)), [Cd₂(C₈H₁₆N₆)₂Cl₈], has been synthesized and structurally characterized by single‐crystal X‐ray diffraction. In the structure, each Cd^II cation is coordinated by five Cl atoms (two bridging and three terminal) and by one N atom from the 1‐[(1H‐tetrazol‐5‐yl)methyl]‐1,4‐diazoniabicyclo[2.2.2]octane ligand, adopting a slightly distorted octahedral coordination geometry. The bridging bicyclo[2.2.2]octane and chloride ligands link the Cd^II cations into one‐dimensional ribbon‐like N—H...Cl hydrogen‐bonded chains along the b axis. An extensive hydrogen‐bonding network formed by N—H...Cl and C—H...Cl hydrogen bonds, and interchain π–π stacking interactions between adjacent tetrazole rings, consolidate the crystal packing, linking the poymeric chains into a three‐dimensional supramolecular network.     

Syntheses,structures and characterization of isomorphous CoII and NiII coordination polymers based on 2‐[(1H‐imidazol‐1‐yl)methyl]‐6‐methyl‐1H‐benzimidazole and benzene‐1,4‐dicarboxylate

Careful choice of the organic ligands is one of the most important parameters in the rational design and synthesis of coordination polymers. Aromatic polycarboxylates have been widely used in the preparation of metal–organic polymers since they can utilize various coordination modes to form diverse structures and can act as hydrogen‐bond acceptors and donors in the assembly of supramolecular structures. Nitrogen‐heterocyclic organic compounds have also been used extensively as ligands for the construction of polymers with interesting structures. In the polymers catena‐poly[[[diaquabis{2‐[(1H‐imidazol‐1‐yl)methyl]‐6‐methyl‐1H‐benzimidazole‐κN ³}cobalt(II)]‐μ₂‐benzene‐1,4‐dicarboxylato‐κ²O ¹:O ⁴] dihydrate], {[Co(C₈H₄O₄)(C₁₂H₁₁N₄)₂(H₂O)₂]·2H₂O}_n , (I), and catena‐poly[[[diaquabis{2‐[(1H‐imidazol‐1‐yl)methyl]‐6‐methyl‐1H‐benzimidazole‐κN ³}nickel(II)]‐μ₂‐benzene‐1,4‐dicarboxylato‐κ²O ¹:O ⁴] dihydrate], {[Ni(C₈H₄O₄)(C₁₂H₁₁N₄)₂(H₂O)₂]·2H₂O}_n , (II), the Co^II or Ni^II ion lies on an inversion centre and exhibits a slightly distorted octahedral coordination geometry, coordinated by two N atoms from two imidazole rings and four O atoms from two monodentate carboxylate groups and two water molecules. The dicarboxylate ligands bridge metal ions forming a polymeric chain. The 2‐[(1H‐imidazol‐1‐yl)methyl]‐6‐methyl‐1H‐benzimidazole ligands coordinate to the Co^II or Ni^II centres in monodentate modes through an imidazole N atom and are pendant on opposite sides of the main chain. The two structures are isomorphous. In the crystal, the one‐dimensional chains are further connected through O—H…O, O—H…N and N—H…O hydrogen bonds, leading to a three‐dimensional supramolecular architecture. In addition, the IR spectroscopic properties, PXRD patterns, thermogravimetric behaviours and fluorescence properties of both polymers have been investigated.     

Temperature‐induced solid‐to‐solid transformation in helical homochiral coordination polymers

The reactions of (R)‐ and (S)‐4‐(1‐carboxyethoxy)benzoic acid (H₂CBA) with 1,3‐bis(2‐methyl‐1H‐imidazol‐1‐yl)benzene (1,3‐BMIB) ligands afforded a pair of homochiral coordination polymers (CPs), namely, poly[[[μ‐1,3‐bis(2‐methyl‐1H‐imidazol‐1‐yl)benzene][μ‐(S)‐4‐(1‐carboxylatoethoxy)benzoato]zinc(II)] monohydrate], {[Zn(C₁₀H₈O₅)(C₁₄H₁₄N₄)]·H₂O}_n or {[Zn{(S)‐CBA}(1,3‐BMIB)]·H₂O}_n ( 1‐L ), and poly[[[μ‐1,3‐bis(2‐methyl‐1H‐imidazol‐1‐yl)benzene][μ‐(R)‐4‐(1‐carboxylatoethoxy)benzoato]zinc(II)] monohydrate] ( 1‐D ). Three kinds of helical chains exist in compounds 1‐D and 1‐L , which are constructed from Zn^II atoms, 1,3‐BMIB ligands and/or CBA^2? ligands. When the as‐synthesized crystals of 1‐L and 1‐D were further heated in the mother liquor or air, poly[[μ‐1,3‐bis(2‐methyl‐1H‐imidazol‐1‐yl)benzene][μ‐(S)‐4‐(1‐carboxylatoethoxy)benzoato]zinc(II)], [Zn(C₁₀H₈O₅)(C₁₄H₁₄N₄)]_n or [Zn{(S)‐CBA}(1,3‐BMIB)]_n ( 2‐L ), and poly[[μ‐1,3‐bis(2‐methyl‐1H‐imidazol‐1‐yl)benzene][μ‐(R)‐4‐(1‐carboxylatoethoxy)benzoato]zinc(II)] ( 2‐D ) were obtained, respectively. The single‐crystal structure analysis revealed that 2‐L and 2‐D only contained one type of helical chain formed by Zn^II atoms and 1,3‐BMIB and CBA^2? ligands, which indicated that the helical chains were reconstructed though solid‐to‐solid transformation. This result not only means the realization of helical transformation, but also gives a feasible strategy to build homochiral CPs.     

A new copper(II) supramolecular coordination polymer and a dinuclear compound with multifunctional 2‐amino‐5‐sulfobenzoic acid and flexible N‐donor ligands: synthesis,structure and characterization

Multifunctional 2‐amino‐5‐sulfobenzoic acid (H₂afsb) can exhibit a variety of roles during the construction of supramolecular coordination polymers. The pendant carboxylic acid, sulfonic acid and amino groups could not only play a role in directing bonding but could also have the potential to act as hydrogen‐bond donors and acceptors, resulting in extended high‐dimensional supramolecular networks. Two new Cu^II coordination compounds, namely catena‐poly[[[diaquacopper(II)]‐μ‐1,6‐bis(1H‐1,2,4‐triazol‐1‐yl)hexane‐κ²N⁴:N^4′] bis(3‐amino‐4‐carboxybenzenesulfonate) dihydrate], {[Cu(C₁₀H₁₆N₆)₂(H₂O)₂](C₇H₆NO₅S)₂·2H₂O}_n or {[Cu(bth)₂(H₂O)₂](Hafsb)₂·2H₂O}_n, (1), and bis(μ‐2‐amino‐5‐sulfonatobenzoato‐κ²O¹:O^1′)bis{μ‐1,2‐bis[(1H‐imidazol‐1‐yl)methyl]benzene‐κ²N³:N^3′}bis[aquacopper(II)] trihydrate, [Cu₂(C₇H₅NO₅S)₂(C₁₄H₁₄N₄)₂(H₂O)₂]·3H₂O or [Cu₂(afsb)₂(obix)₂(H₂O)₂]·3H₂O, (2), have been obtained through the assembly between H₂afsb and the Cu^II ion in the presence of the flexible N‐donor ligands 1,6‐bis(1H‐1,2,4‐triazol‐1‐yl)hexane (bth) and 1,2‐bis[(1H‐1,2,4‐triazol‐1‐yl)methyl]benzene (obix), respectively. Compound (1) consists of a cationic coordination polymeric chain and 3‐amino‐4‐carboxybenzenesulfonate (Hafsb⁻) anions. Compound (2) exhibits an asymmetric dinuclear structure. There are hydrogen‐bonded networks within the lattices of (1) and (2). Interestingly, both (1) and (2) exhibit reversible dehydration–rehydration behaviour.