Three Cd(ii) coordination polymers constructed from a series of multidentate ligands derived from cyclotriphosphazene: synthesis, structures and luminescence properties†
Abstract
By utilizing three ligands derived from cyclotriphosphazene, three novel cadmium-based coordination polymers (CPs), namely, {[Cd3(L1)(H2O)5]}n (1), {[Cd4(H2L2)2(H2O)8]}n (2) and {[Cd2(H2L3)2(H2O)2]·(H2O)}n (3), (H6L1 = hexakis(4-carboxylatophenoxy)cyclotriphosphazene, H6L2 = hexakis(3-carboxylatophenoxy)cyclotriphosphazene, H6L3 = hexakis(4-(1H-tetrazol-5-yl)phenoxy)cyclotriphosphazene), have been successfully synthesized and structurally characterized. Their distinct topological architectures must be ascribed to the coordination conformations of the flexible ligands along with the different sites and coordination modes of the coordination groups. 1 exhibits a 3D topological structure based on the connection of trinuclear units and fully deprotonated L1 ligands. Just by changing the position of the carboxylate groups, a 2D layer structure with dinuclear units and partially deprotonated L2 ligands has been constructed. Comparably, by substituting the carboxylate by tetrazole groups, a distinct 3D structure with tetranuclear units has been synthesized. In addition, the three Cd CPs exhibit the corresponding photo-chemical properties in accordance with their structures.