Three transition metal complexes constructed from a rigid 2,2′-bipyridine-3,3′,6,6′-tetracarboxylic acid ligand: Syntheses, structures and their fluorescence properties

• Three complexes constructed from a rigid tetracarboxylic acid ligand were synthesized and characterized.
• The bptcH4 ligand with various conformations is recognized in assemblies.
• The Cu(II) ion are chelated by bptcH4 ligand to give a dinuclear copper building block.

Three complexes, {[Cd(bptcH2)(H2O)]·H2O}n (1), {[Cu(bptc)0.5(H2O)]·H2O}n (2), {[Co2(bptc)(H2O)6]·3H2O}n (3) (bptcH4 = 2,2′-bipyridine-3,3′,6,6′-tetracarboxylic acid) have been synthesized by self-assembly of the rigid bptcH4 ligand and corresponding transition metal salts. The structural analysis indicates that complex 1 displays a two-dimensional (2D) puckered sheet with (44·62) topology built from 4-connecting Cd3N2(OOC)3 cluster and bridging ligand bptcH22−. Complex 2 features a one-dimensional (1D) double-stranded chain made up 4-connecting bptc4− and Cu4N2(OOC)4 cluster. Complex 3 also exhibits a 2D grid with (44·62) topology, similar to that of complex 1. In addition, the fluorescence properties of complexes 1 and 3 have also been explored.

Three new complexes assembled with 2,2′-bipyridine-3,3′,6,6′-tetracarboxylic acid ligand have been synthesized under hydrothermal conditions. The bptcH4 ligand with plentiful chemical information displays diverse coordination modes. And, the complexes exhibit strong luminescent properties.Figure optionsDownload as PowerPoint slide