Zinc(II) coordination polymers with 3-(1H-imidazol-1-yl)propanoate linkers.

Coordination polymers of zinc(II) with three readily accessible 3-(1H-imidazol-1-yl)propanoate ligands are prepared by combining aqueous solutions of the ligands and zinc(II) salts, resulting in a precipitation of the respective coordination polymers. While sodium 3-(1H-imidazol-1-yl)propanoate and sodium 3-(2-phenyl-1H-imidazol-1-yl)propanoate initially yield amorphous precipitates that can be converted to crystalline materials upon prolonged heating, the use of sodium 3-(2-methyl-1H-imidazol-1-yl)propanoate results in the immediate formation of a crystalline coordination polymer. All three coordination polymers were structurally characterized by single crystal X-ray diffraction. The crystal water in one coordination polymer could be removed without losing the crystallinity of the sample and this process was studied by infrared spectrometry. The interpretation of the corresponding infrared spectra was supported by theoretical calculations. Furthermore, the solubility in water and buffer solutions as well as the potential porosity of the coordination polymers were investigated, revealing their non-porous character for CO2, N2 and CH4.