Syntheses, structures and luminescent properties of zinc(ii) coordination polymers based on bis(imidazole) and dicarboxylate

Abstract

Five zinc(II) coordination polymers with 5-methylisophthalic acid (H₂L1), 5-methoxylisophthalic acid (H₂L2) and bridging bis(imidazole) ligands, [Zn(L1)(biim-3)]_n (1), [Zn(L1)(biim-6)]_n (2), [Zn(L1)(biim-5)]_n (3), [Zn(L2)(biim-3)]_n (4) and [Zn(L2)(biim-6)]_n (5) (biim-3 = 1,3-bis(imidazole)propane, biim-5 = 1,5-bis(imidazole)pentane, biim-6 = 1,6-bis(imidazole)hexane), have been hydrothermally synthesized and structurally characterized. Compound 1 shows a two-dimensional (4,4) net which contains left- and right-handed helical chains. Compounds 2 and 3 are both 3-fold parallel interpenetrated 2D → 3D architecture while 4 shows a 2-fold parallel interpenetrated 3D → 3D architecture and contains two kinds of chiral layers. Compound 5 exhibits a 2-fold parallel interpenetrated 2D → 2D (4,4) net. Furthermore, luminescent properties and thermo-gravimetric properties of these compounds were investigated. The results suggest that both carboxylate and bis(imidazole) ligands influence on the final resulting complexes.