New Mg-based 4,4’-biphenyldicarboxylate Coordination Polymer with Layered Crystal Structure

Abstract

New magnesium 4,4’-biphenyldicarboxylate (BPDC) was solvothermally synthesized in the presence of N,N’-dimethylformamide (DMF). The crystal structure with formula Mg₃(BPDC)₃(DMF)₄ and denoted as NICS-7 was solved in monoclinic symmetry with space group Pn (no. 7) and unit cell parameters a = 12.6433(7) Å, b = 13.3950(5) Å, c = 19.9230(8) Å, β = 107.131(5) °. The structure consists of MgO₆ linear arranged trimers with common vertices connected through BPDC ligands forming extended 2-dimensional layered hybrid structure. Each terminal Mg atom within trimeric clusters is coordinated by two dimethylformamide molecules, respectively. Layers of Mg₃(BPDC)₃(DMF)₄ are stabilized by non-coordinated dimethylformamide molecules located within the voids in crystallographically disordered manner. Thermal properties of NICS-7 were determined by thermogravimetric and temperature-programmed X-ray diffraction. The structure remains stable only up to 50 °C. At higher temperatures, the removal of non-coordinated dimethylformamide molecules causes formation of amorphous Mg-BPDC phase.