Two new two-dimensional coordination polymers based on isophthalate and a flexible N-donor ligand containing benzimidazole and pyridine rings: synthesis, crystal structures and a solid-state UV-Vis study

In coordination chemistry and crystal engineering, many factors influence the construction of coordination polymers and the final frameworks depend greatly on the organic ligands used. N-Donor ligands with diverse coordination modes and conformations have been employed to assemble metal-organic frameworks. Carboxylic acid ligands can deprotonate completely or partially when bonding to metal ions and can also act as donors or acceptors of hydrogen bonds and are thus good candidates for the construction of supramolecular architectures. Two new transition metal complexes, namely poly[diaqua(μ₄-1,4-bis{[1-(pyridin-3-ylmethyl)-1H-benz[d]imidazol-2-yl]methoxy}benzene)bis(μ₂-isophthalato)dicobalt(II)], [Co(C₈H₄O₄)(C₃₄H₂₈N₆O₂)_0.5(H₂O)]_n, (1), and poly[diaqua(μ₄-1,4-bis{[1-(pyridin-3-ylmethyl)-1H-benz[d]imidazol-2-yl]methoxy}benzene)bis(μ₂-isophthalato)dicadmium(II)], [Cd(C₈H₄O₄)(C₃₄H₂₈N₆O₂)_0.5(H₂O)]_n, have been constructed using a symmetric N-donor ligand and a carboxylate ligand under hydrothermal conditions. X-ray crystallographic studies reveal that complexes (1) and (2) are isostructural, both of them exhibiting three-dimensional supramolecular architectures built by hydrogen bonds in which the coordinated water molecules serve as donors, while the O atoms of the carboxylate groups act as acceptors. Furthermore, (1) and (2) have been characterized by elemental, IR spectroscopic, powder X-ray diffraction (PXRD) and thermogravimetric analyses. The UV-Vis absorption spectrum of complex (1) has also been investigated.

Highly efficient electrochemiluminescence based on pyrazolecarboxylic metal organic framework

A series of transition metal complexes with the ligands 3-pyrazoledicarboxylic acid (H₂L¹) and ethyl 1-(2-ethoxy-2-oxoethyl)-1H-pyrazole-3-carboxylate (epzc) have been synthesized.

Synthesis, structure and characterization of two new metal–organic coordination polymers based on the ligand 5-iodobenzene-1,3-dicarboxylate

Two new coordination polymers (CPs) formed from 5-iodobenzene-1,3-dicarboxylic acid (H2iip) in the presence of the flexible 1,4-bis(1H-imidazol-1-yl)butane (bimb) auxiliary ligand, namely poly[[μ2-1,4-bis(1H-imidazol-1-yl)butane-κ2N3:N3′](μ3-5-iodobenzene-1,3-dicarboxylato-κ4O1,O1′:O3:O3′)cobalt(II)], [Co(C8H3IO4)(C10H14N4)]nor [Co(iip)(bimb)]n, (1), and poly[[[μ2-1,4-bis(1H-imidazol-1-yl)butane-κ2N3:N3′](μ2-5-iodobenzene-1,3-dicarboxylato-κ2O1:O3)zinc(II)] trihydrate], {[Zn(C8H3IO4)(C10H14N4)]·3H2O}nor {[Zn(iip)(bimb)]·3H2O}n, (2), were synthesized and characterized by FT–IR spectroscopy, thermogravimetric analysis (TGA), solid-state UV–Vis spectroscopy, single-crystal X-ray diffraction analysis and powder X-ray diffraction analysis (PXRD). The iip2−ligand in (1) adopts the (κ1,κ1-μ2)(κ1, κ1-μ1)-μ3coordination mode, linking adjacent secondary building units into a ladder-like chain. These chains are further connected by the flexible bimb ligand in atrans–trans–transconformation. As a result, a twofold three-dimensional interpenetrating α-Po network is formed. Complex (2) exhibits a two-dimensional (4,4) topological network architecture in which the iip2−ligand shows the (κ1)(κ1)-μ2coordination mode. The solid-state UV–Vis spectra of (1) and (2) were investigated, together with the fluorescence properties of (2) in the solid state.

Effects of hydroxy substituents on Cu(ii) coordination polymers based on 5-hydroxyisophthalate derivatives and 1,4-bis(2-methylimidazol-1-yl)benzene

Hydroxyl substituents of 5-hydroxyisophthalate derivatives have imposed important effects on the structures and properties of Cu(ii) coordination polymers.