A complete vibrational study on a potential environmental toxicant agent, the 3,3',4,4'-tetrachloroazobenzene combining the FTIR, FTRaman, UV-Visible and NMR spectroscopies with DFT calculations.

MARÍA V. CASTILLO; JORGELINA L. PERGOMET; GUSTAVO A. CARNAVALE; LILIAN DAVIES; JUAN ZINCZUK; SILVIA A. BRANDÁN

SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY.

PERGAMON-ELSEVIER SCIENCE LTD

Lugar: Amsterdam; Año: 2015 vol. 134 p. 577 - 586

1386-1425

In this study 3,3,4,4-tetrachloroazobenzene (TCAB) was prepared and then characterized by infrared,Raman, multidimensional nuclear magnetic resonance (NMR) and ultraviolet?visible spectroscopies. The density functional theory (DFT) together with the 6-31*G and 6-311++G ** basis sets were used to study the structures and vibrational properties of the twocisandtransisomers of TCAB. The harmonic vibrational wavenumbers for the optimized geometries were calculated at the same theory levels. A complete assignment of all the observed bands in the vibrational spectra of TCAB was performed combining the DFT calculations with the scaled quantum mechanical force field (SQMFF) methodology. The molecular electrostatic potentials, atomic charges, bond orders and frontier orbitals for the two isomers of TCAB properties were calculated by employingBader?sAtoms in the Molecules (AIM) theory. This study shows that thecisandtransisomers exhibit different structural and vibrational properties and absorption bands were compared and analyzed. The comparison of the theoretical ultraviolet?visible spectrum with the corresponding experimental demonstrates a good concordance while the calculated 1H and 13 C chemicals shifts are in good conformity with the corresponding experimental NMR spectra of TCAB in solution. p * transitions for both forms were studied by natural bond orbital (NBO) while the topological