Structural diversity and luminescence properties of coordination polymers built with a rigid linear dicarboxylate and Zn(II)/Pb(II) Ion

Abstract

A rigid linear ligand incorporating a carboxylic acid group at either end, p-terphenyl-4,4″-dicarboxylic acid, 2′,5′- dimethyl (H2L) has been used to construct four coordination polymers with Zn(II) through solvothermal techniques. The four products formed are formulated as {[Zn3(L)2(OH)2]·8EtOH·4DMF}n (1), {[Zn(L)(bpmp)0.5]·EtOH·1/2DMF}n (2), {[(Zn)0.5(L)0.5(py)0.5]·5/2DMF·EtOH}n (3), and [Zn(L)(HNMe2)]n (4). With Pb(NO3)2 the ligand affords two polymers, {[Pb2(L)1.5(O)0.5]·EtOH·2H2O}n (5) and {[Pb3(L)3(H2O)]·6H2O}n (6). All of these compounds have been characterized by single crystal X-ray diffraction, infrared spectroscopy, thermogravimetry, elemental analysis, and powder X-ray diffraction measurements. Topological analyses reveal that complex 2 is a 6-connected pcu net, while complexes 3 and 4 are simplified as a 4-connected sql net. In the case of complexes 1 and 6, one-dimensional rod-shaped metal carboxylate based secondary building units have been obtained. However, an uncommon structure and topology have been obtained in complex 5. Surprisingly, such type of parallel ladder-like packing is not explored much in coordination polymers. Solid-state photoluminescence studies have been carried out for all of the complexes upon excitation at 347 nm at room temperature.