Metal [Zn(II), Cd(II)], 1,10-Phenanthroline Containing Coordination Polymers Constructed on the Skeleton of Polycarboxylates: Synthesis, Characterization, Microstructural, and CO₂ Gas Adsorption Studies

Abstract

Four new coordination polymers have been obtained by the reaction of metal [Zn(II), Cd(II)], 1,10-phenanthroline separately with two carboxylic acids, [biphenyl-4,4^′-dicarboxylic acid (4,4^′-H2BDA),and 4,4^′-azodibenzoic acid (4,4^′-H₂BDA)]. The crystal structures of the resulting complexes of type {[Zn(4,4^′-BDA)(Phen)]₂·HCON(CH₃)₂}_n (1), {[Cd(4,4^′-BDA)(Phen)]₂·H₂O}_n (2), {[Zn(4,4^′-ADA)(Phen)]₂}_n (3), and [Zn(4,4^′-ADA)(Phen)(H₂O)₂]n (4) have been elucidated using their single-crystal X-ray diffraction analysis. Their thermal stabilities have been investigated using thermogravimetric analysis. Complexes result in a 2D structure with channel formation. SEM studies show a coordination-induced effect on their morphology. Grain and flowery morphology of uncoordinated ligands 4,4^′-H2BDA and 4,4^′-H₂BDA, respectively, changes on coordination with metal salts. SEM micrographs of complexes exhibit ridged surface, cracks of 2 μm width, parallelopiped structure, and feathery appearance for 1, 2, 3, and 4, respectively. Complexes show moderate adsorption of CO₂ gas.