In situ formation of 4-cyanopyridinecarboxylic acid and its polyacid doping coordination polymer for adsorption of organic dyes in wastewater

Abstract

Through adjusting the different ligands and incorporating 4, 4′-bipyridine, two novel POM-based inorganic–organic hybrid compounds {[(Cu·L1′·(4, 4′-bpy)2·2H2O)]·(β-Mo8O26)}n (1) and {[Cu·L2′·(4, 4′-bpy)]·[Cu·L2′·(β-Mo8O26)]·4H2O}n (2) [4, 4′-bpy = 4, 4′-bipyridine, L1′=1, 4-bis(pyridinio-4-carboxylato)-butane, L2′=1, 6-bis(pyridinio-4-carboxylato)-hexane] have been synthesized under different hydrothermal conditions. The two compounds were assembled by 4, 4′-bpy, CuCl2, carboxyl ligands from in-situ hydrolysis of cyano group and POM clusters, which are rarely observed in POM-based inorganic–organic hybrid compounds. Compounds 1–2 were characterized by single crystal X-ray diffraction, infrared spectrum (IR), and powder X-ray diffraction (PXRD). Compounds 1–2 have been studied for removal of organic dyes such as methylene blue (MB), methyl orange (MO) and rhodamine B (RhB).