Preparation, Crystal Structures and Photoluminescence of Two New Zinc Complexes Based on 1H-Imidazo[4,5-f][1,10]-phenanthroline and Auxiliary Ligands

Two new coordination polymers [Zn(ip)(2,5-tda)(H2O)2]n (1) and [Zn2(ip)2(5-npa)2]n (2) (2,5-tda = thiophene-2,5-dicarboxylic acid, ip = 1H-imidazo[4,5-f][1,10]-phenanthroline and 5-npa = 5-Nitroisophthalic acid) were synthesized and characterized by IR, elemental analysis, PXRD and X-ray diffraction. Single-crystal X-ray analyses revealed that 1 and 2 demonstrate a 1D chain structure. Complex 1 was bridged by 2,5-tda ligands in a μ1 − η1:η0/μ1 − η1:η0 coordination mode, and further extended into a 2D supramolecular structure by hydrogen bonding and π···π interactions. In 2, the 5-npa ligand acts as a bridging moeity, exhibiting μ1 − η1:η1/μ1 − η1:η0 and μ1 − η1:η0/μ1 − η1:η0 coordination modes to link metal ions to form a 1D chain. The chains are further connected via hydrogen bonding interactions into a 2D supramolecular structure. The luminescent properties for 1 and 2 were investigated in the solid state at room temperature.