Coordination Complexes of Cd(II), Cu(II), Zn(II), and Substituted Diimide Ligands: Syntheses, Structural Analyses and Gas Sorption Studies

We report the syntheses, structural and thermal analyses of four coordination complexes namely Cd (L1) 2 (NDC) ·4DMFn·1, CuL2·DMFn·2, Zn (L3) 0. 5 (DDN) ·DMFn·3 and Zn (L4) 0. 5 (DDN) ·DMF·H2On 4. Here, L1 is 2, 2′-bis (pyridin-4-ylmethyl) -5, 5′-biisoindoline-1, 1′, 3, 3′-tetraone; L2 is 2, 2′- (1, 1′, 3, 3′-tetraoxo-5, 5′-biisoindoline-2, 2′-diyl) diacetic acid; L3 is 2, 7-bis (pyridin-3-ylmethyl) benzo lmn3, 8phenanthroline-1, 3, 6, 8 (2H, 7H) -tetraone; L4 is 2, 7-bis (pyridin-4-ylmethyl) benzolmn3, 8 phenanthroline-1, 3, 6, 8 (2H, 7H) -tetraone; DMF is N, N-dimethylformamide; H2NDC is 2, 6-naphthalene dicarboxylic acid; and H2DDN is 6, 6′-dithiodinicotinic acid. Complexes 1, 3, and 4 are three-dimensional, while complex 2 is two-dimensional. Powder X-ray diffraction indicates that complex 1 changes its structure upon desolvation but does not revert to its original form when exposed to DMF. Carbon dioxide (CO2) sorption studies on 1 indicate that the complex adsorbs minimal amounts of CO2 at 273 K.