Dimensionality of luminescent coordination polymers of magnesium ions and 1,1'-ethynebenzene-3,3',5,5'-tetracarboxylic acid modulated by structural inducing agents.

Solvothermal reactions of aromatic 1,1'-ethynebenzene-3,3',5,5'-tetracarboxylic acid (HEBTC) and Mg salts in the presence of different supporting ligands afforded the coordination polymers [Mg(HEBTC)(DMF)(HO)] (1), [Mg(HEBTC)(HO)]·solvent (2) and [Mg(EBTC)(HO)]·solvent (3). The crystal structures of 1-3 were determined by the single crystal X-ray diffraction technique, where CP 1 showed a one-dimensional zigzag MgO coordination octahedral chain structure; 2 exhibited a two-dimensional MgO coordination octahedral framework with trinuclear [Mg(COO)] SBUs, and 3 featured a three-dimensional MgO coordination octahedral framework with binuclear [MgO(COO)] SBUs. The various structures in CPs 1-3 of Mg ions with the HEBTC ligand were ascribed to the conformational flexibility and the coordination mode diversity of the HEBTC ligand. Interestingly, the zwitterionic supporting ligand 2-aminoterephthalic acid or 4-aminobenzenesulphonic acid played a vital role in the initial formation process of nuclear crystals but only as a structural induction agent, which modulated the dimensionality of these Mg-based CPs. Additionally, the three CPs emitted bright blue luminescence at ambient conditions, and the emission lifetimes and absolute quantum yields were also investigated.