Two New Coordination Polymers with Co(II) and Mn(II): Selective Gas Adsorption and Magnetic Studies

A novel bifurcated ligand 3,5-di(1H-benzo[d]imidazol-1-yl)-benzonitrile (DBIBN) has been synthesized, which reacts with Co(II) and Mn(II) salts to form new coordination polymers {[Co-2(DBIBA)(3)]center dot Cl center dot 9H(2)O}(n) (1) and {[Mn-3(DBIBA)(6)]}(n) (2), (DBIBA = 3,5-di(1H-benzo[d]imidazol-1-yl)-benzoate), in which DBIBN get hydrolyzed into DBIBA under solvothermal conditions. Both the complexes have been characterized by single-crystal X-ray crystallography (XRD), IR spectroscopy, elemental analysis, thermogravimetry, and X-ray powder diffraction (PXRD). Complex 1 is a 3D coordination polymer composed of binuclear Co(II) units, having (4,6) connected net. On the other hand, complex 2 is a layered structure with trinuclear Mn(II) units, which has 4-connected 4(4) sql topology. TGA and PXRD measurements show that the framework 1 is stable after desolvation. Desolvated framework 1 showed selective adsorption of CO2 over N-2, H-2 and Ar. Variable temperature magnetic susceptibility measurements show that complex 1 exhibits weak antiferromagnetic behavior.