Structure diversity of a series of new coordination polymers based on a C3-symmetric tridentate ligand with rosette architecture

Abstract

4,4′,4″-[1,3,5-Benzenetriyltris(carbonylimino)]trisbenzoic acid (H3L), a C3-symmetric ligand, was found to self-assemble into an interesting core-rosette structure driven by intermolecular hydrogen-bonding interactions. Reactions of this ligand with Zn2+, Co2+ and Cd2+ under solvothermal conditions resulted in the formation of four new coordination polymers with interesting structural motifs: [Zn2(L)(OH)(H2O)(DMF)]·DMF·H2O (1), [Co3(L)2(DMF)(H2O)]·DMF·3CH3OH (2), [Co1.5(L)(H2O)(DMF)]·DMF (3), and [Cd1.5(L)(H2O)(DMF)]·DMF (4). Single-crystal structural analysis revealed that complex 1 exhibits a rare example of twofold interpenetrating two-dimensional CdI2-type structure with tetranuclear Zn4(μ3-OH)2(COO)6(H2O)(DMF) serving as secondary building unit (SBU), whereas in 2, the μ3-oxo-tricobalt basic carboxylate SBUs are connected by L3− ligands, leading to a twofold interpenetrating three-dimensional (3,6)-net framework. The isomorphous complexes 3 and 4 each has a (4,4)-grid layered architecture in which the SBU is a linear Co3/Cd3 cluster. The four coordination polymers were all further characterized by IR, thermogravimetric and powder X-ray diffraction (PXRD).