Molecular structure and spectroscopic analysis of homovanillic acid and its sodium salt--NMR, FT-IR and DFT studies.

The estimation of the electronic charge distribution in metal complex or salt allows to predict what kind of deformation of the electronic system of ligand would undergo during complexation. It also permits to make more precise interpretation of mechanism by which metals affect the biochemical properties of ligands. The influence of sodium cation on the electronic system of homovanillic acid was studied in this paper. Optimized geometrical structures of studied compounds were calculated by B3LYP/6-311++G** method. Mulliken, MK and ChelpG atomic charges were analyzed. The theoretical NMR and IR spectra were obtained. H-1 and C-13 NMR as well as FT-IR and FT-Raman spectra of studied compounds were also recorded and analyzed. The calculated parameters are compared with experimental characteristics of these molecules. (C) 2013 Elsevier B.V. All rights reserved.