Structure diversity of a series of new coordination polymers based on a C _3-symmetric tridentate ligand with rosette architecture

摘要

4,4′,4″-[1,3,5-Benzenetriyltris(carbonylimino)]trisbenzoic acid (H _3L), a C _3-symmetric ligand, was found to self-assemble into an interesting core-rosette structure driven by intermolecular hydrogen-bonding interactions. Reactions of this ligand with Zn ~(2+), Co ~(2+) and Cd ~(2+) under solvothermal conditions resulted in the formation of four new coordination polymers with interesting structural motifs: [Zn _2(L)(OH)(H _2O)(DMF)]·DMF·H _2O (1), [Co _3(L) _2(DMF)(H _2O)] ·DMF·3CH _3OH (2), [Co _(1.5)(L)(H _2O)(DMF)]·DMF (3), and [Cd _(1.5)(L)(H _2O)(DMF)]·DMF (4). Single-crystal structural analysis revealed that complex 1 exhibits a rare example of twofold interpenetrating two-dimensional CdI 2-type structure with tetranuclear Zn _4(μ _3-OH) _2(COO) _6(H _2O)(DMF) serving as secondary building unit (SBU), whereas in 2, the μ _3-oxo-tricobalt basic carboxylate SBUs are connected by L ~(3-) 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 Co _3/Cd _3 cluster. The four coordination polymers were all further characterized by IR, thermogravimetric and powder X-ray diffraction (PXRD).