Zinc(II) and cadmium(II) coordination polymers containing phenylenediacetate and bis(imidazol-1-ylmethyl)benzene linkers: The effect of ligand isomers on the solid state structures

Abstract

This work presents a systematic investigation of the reactions of o-, m- and p-phenylenediacetic acid with Zn(II)/Cd(II) salts in the presence of different semi-rigid o-, m- and p-bis(imidazol-1-ylmethyl)benzene co-ligands. Fourteen new coordination polymers – {[Zn(μ-opda)(µ-mbix)]·0.5H2O}n (1), {[Zn(μ-mpda)(µ-obix)]·H2O}n (2), {[Zn2(μ-mpda)2(μ-mbix)2]·5H2O}n (3), {[Zn(μ-mpda)(µ-mbix)]·2H2O}n (4), {[Zn(μ-mpda)(µ-pbix)]·0.5H2O}n (5), [Zn(μ-ppda)(μ-obix)]n (6), {[Zn(μ-ppda)(µ-mbix)]·0.5H2O}n (7), {[Zn(μ-ppda)(μ-pbix)]·H2O·DMF}n (8), {[Cd(μ-mpda)(μ-obix)1.5]·H2O}n (9), {[Cd(μ-mpda)(μ-obix)]·H2O}n (10), {[Cd(μ-mpda)(μ-mbix)(H2O)]·H2O}n(11), [Cd(μ3-ppda)(µ-obix)]n (12), [Cd(μ3-ppda)(µ-mbix)]n (13) and [Cd(μ3-ppda)(µ-pbix)]n (14) (o/m/ppda=1,2/1,3-/1,4-phenylenediacetate, o/m/pbix=1,2-/1,3-/1,4-bis(imidazol-1-ylmethyl)benzene) – have been prepared and structurally characterized. Two of the complexes were found to possess one-dimensional (1D) structures, eleven complexes were found to be two-dimensional (2D) coordination networks and one of the complexes was found to be a three-dimensional (3D) coordination network. Of the 1D structures, 3 forms nanotubes, whereas in 8 pairs of pbix ligands bridge the zinc(II) centers to generate Zn2(pbix)2 dimers, which in turn are linked together by pairs of ppda linkers to give chains. Compound 5 contains a 4-fold interpenetrated 3D framework. The structure of 10 contains interpenetrated 2D frameworks, leading to a three-dimensional gross structure. The thermal stabilities and luminescent properties for 1–14 are also reported.