Structures and properties of coordination polymers involving asymmetric biphenyl-3,2′,5′-tricarboxylate†
Abstract
An asymmetric polycarboxylate ligand, biphenyl-3,2′,5′-tricarboxylic acid (H3bptc) with a rotatable coordination vertex, was employed to react with metal ions under hydrothermal conditions. Four new coordination polymers {[Mn3(bptc)2(4,4′-bpy)3(H2O)2]}n (1), {[Ni(Hbptc)(4,4′-bpy)1.5(H2O)2]·H2O}n (2), {[Cd2(Hbptc)2(phen)4]·3H2O}n (3) and {[Cu2(Hbptc)2(2,2′-bpy)2(H2O)2]·2H2O}n (4) were successfully synthesized and characterized. Single crystal X-ray analysis revealed that compound 1 has a 3D coordination network with linear Mn(II)3-based subunits, while 2 is a 1D ladder chain-based structure further interconnected by hydrogen bonds to a 3D supramolecular network. Compounds 3 and 4 are each composed of a supramolecular network, which is supported by hydrogen bonds and π⋯π interactions and consists of dimers, [Cd2(Hbptc)2(phen)4] and [Cu2(Hbptc)2(2,2′-bpy)2], respectively. The conformation stability and coordination modes of the H3bptc ligand have been discussed. The magnetic and fluorescent properties of the complexes have been investigated.