Hydrogen bonding interactions in the 2,2′-bipyridine–pyromellitic acid complex IR, nuclear magnetic resonance and theoretical studies

Abstract

The stability of the complex formed between 2,2′-bipyridine and pyromellitic acid (1,2,4,5-benzenetetracarboxylic acid) in gaseous, liquid and solid state has been studied by using experimental and theoretical methods. The complex has been shown to be stable in gaseous and solid states, while in solution interactions via new hydrogen bonds occurred between 2,2′-bipyridine or pyromellitic acid and solvent molecules. Structural parameters and interaction energies of such new hydrogen bonded complexes determined by quantum chemical calculations have substantiated the experimental observations. Correlations have been found between the hydroxy proton chemical shifts and calculated association energies and between carbon chemical shifts and the change in p character of the carboxyl carbon.