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 (H 4 EBTC) and Mg 2+ salts in the presence of different supporting ligands afforded the coordination polymers [Mg(H 2 EBTC)(DMF) 2 (H 2 O) 2 ] (1), [Mg 3 (HEBTC) 2 (H 2 O) 4 ]·solvent (2) and [Mg 2 (EBTC)(H 2 O) 5 ]·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 6 coordination octahedral chain structure; 2 exhibited a two-dimensional MgO 6 coordination octahedral framework with trinuclear [Mg 3 (COO) 6 ] SBUs, and 3 featured a three-dimensional MgO 6 coordination octahedral framework with binuclear [Mg 2 O(COO) 2 ] SBUs. The various structures in CPs 1-3 of Mg 2+ ions with the H 4 EBTC ligand were ascribed to the conformational flexibility and the coordination mode diversity of the H 4 EBTC 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 2+ -based CPs. Additionally, the three CPs emitted bright blue luminescence at ambient conditions, and the emission lifetimes and absolute quantum yields were also investigated.