Structure diversity of a series of new coordination polymers based on a C ₃-symmetric tridentate ligand with rosette architecture

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).