Three isomorphous two-dimensional coordination polymers generated from a benzimidazole bridging ligand and ZnX₂ (X = Cl, Br and I)

A novel bridging asymmetric benzimidazole ligand, 4-{2-[3-(pyridin-4-yl)­phenyl]-1H-benzimidazol-1-yl­methyl}­benzoic acid, was used to construct three isomorphous two-dimensional coordination polymers, namely catena-poly[chlorido(μ₃-4-{2-[3-(pyridin-4-yl)­phenyl]-1H-benzimidazol-1-yl­methyl}­benzoato)­zinc(II)], [Zn(C₂₆H₁₈N₃O₂)Cl]_n, (I), and the bromide, (II), and iodide, (III), analogues. Neighbouring two-dimensional networks are stacked into three-dimensional frameworks via inter­layer π–π inter­actions. The luminescent properties of (I)–(III) were investigated and they display an obvious red-shift in the solid state at room temperature.

Two one-dimensional coordination polymers generated from a new benzimidazole bridging ligand and CdX₂ (X = Br and I)

The novel asymmetric bridging ligand 1-[(pyridin-3-yl)methyl]-2-[4-(pyridin-3-yl)phenyl]-1H-benzimidazole (L) has been used to construct the coordination polymers catena-poly[[[dibromidocadmium(II)]-μ₃-1-[(pyridin-3-yl)methyl]-2-[4-(pyridin-3-yl)phenyl]-1H-benzimidazole] monohydrate], {[CdBr₂(C₂₄H₁₈N₄)]·H₂O}_n, (I), and catena-poly[[diiodidocadmium(II)]-μ₃-1-[(pyridin-3-yl)methyl]-2-[4-(pyridin-3-yl)phenyl]-1H-benzimidazole], [CdI₂(C₂₄H₁₈N₄)]_n, (II). Com­pounds (I) and (II) are closely related one-dimensional polymers based on 16- and 20-membered macrocycles along the chains, but they are not isomorphous. The chains are crosslinked into a two-dimensional network via hydrogen bonds and π–π inter­actions in (I), and into a three-dimensional framework through π–π inter­actions in (II). One well-ordered solvent water mol­ecule per asymmetric unit is included in (I) and forms O...Br hydrogen bonds.

Zn^II and Cu^II complexes generated from 5-(pyridin-4-yl)-3-[2-(pyridin-4-yl)ethyl]-1,3,4-oxa­diazole-2(3H)-thione

A new 1,3,4-oxa­diazole-containing bis­pyridyl ligand, namely 5-(pyridin-4-yl)-3-[2-(pyridin-4-yl)eth­yl]-1,3,4-oxa­diazole-2(3H)-thione (L), has been used to create the novel complexes tetra­nitrato­bis{μ-5-(pyridin-4-yl)-3-[2-(pyridin-4-yl)ethyl]-1,3,4-oxa­diazole-2(3H)-thione}zinc(II), [Zn₂(NO₃)₄(C₁₄H₁₂N₄OS)₂], (I), and catena-poly[[[dinitrato­copper(II)]-bis­{μ-5-(pyridin-4-yl)-3-[2-(pyridin-4-yl)ethyl]-1,3,4-oxa­diazole-2(3H)-thione}] nitrate aceto­nitrile sesqui­solvate di­chloro­methane sesqui­solvate], {[Cu(NO₃)(C₁₄H₁₂N₄OS)₂]NO₃·1.5CH₃CN·1.5CH₂Cl₂}_n, (II). Compound (I) presents a dis­torted rectangular centrosymmetric Zn₂L₂ ring (dimensions 9.56 × 7.06 Å), where each Zn^II centre lies in a {ZnN₂O₄} coordination environment. These binuclear zinc metallocycles are linked into a two-dimensional network through nonclassical C—H...O hydrogen bonds. The resulting sheets lie parallel to the ac plane. Compound (II), which crystallizes as a nonmerohedral twin, is a coordination polymer with double chains of Cu^II centres linked by bridging L ligands, propagating parallel to the crystallographic a axis. The Cu^II centres adopt a distorted square-pyramidal CuN₄O coordination environment with apical O atoms. The chains in (II) are inter­linked via two kinds of π–π stacking inter­actions along [01]. In addition, the structure of (II) contains channels parallel to the crystallographic a direction. The guest components in these channels consist of di­chloro­methane and aceto­nitrile solvent mol­ecules and uncoordinated nitrate anions.

2,5-Bis[4-methyl-3-(pyridin-3-yl)phen­yl]-1,3,4-oxa­diazole and its one-dimensional polymeric complex with ZnCl₂

In a polymer of 2,5-bis­[4-methyl-3-(pyridin-3-yl)phen­yl]-1,3,4-oxa­diazole (L) with ZnCl₂, one-dimensional P (plus) and M (minus) helical chains are formed, where the ligand has different directions of twist. The helical chains stack together via inter­chain π–π and C—H...π inter­actions.

A well-resolved cyclic water tetra­mer in a dinuclear Cu^II coordination complex based on 1,2-bis­(pyridin-3-yl­oxy)ethane and capped by pyridine-2,6-di­carb­oxy­lic acid

Two five-coordinated aqua­copper(II) centres chelated to pyridine-2,6-di­carboxyl­ate terminal ligands are bridged by a 1,2-bis­(pyridin-3-yl­oxy)ethane spacer. The structure includes a well-resolved cyclic water tetra­mer, which acts as a subunit to form a larger aggregate.

The coordination chemistry of two symmetric fluorene-based organic ligands with cuprous chloride

In two complexes, Cu^I atoms connect the symmetric 2,7-bis­(1H-imidazol-1-yl)-9,9-dimethyl-9H-fluorene and 2,7-bis­(1H-imidazol-1-yl)-9,9-dipropyl-9H-fluorene ligands into one-dimensional chains. In the former, a {[Cu^ICl₂]^-} unit adheres to the one-dimensional chain through a weak Cu...Cu inter­action, while in the latter, a {[Cu^I₂Cl₄]^2-} unit links two different chains into a one-dimensional rope-ladder-type chain.