Structural study, coordinated normal analysis and vibrational spectra of 4-hydroxy-3-(3-methyl-2-butenyl) acetophenone

LIZARRAGA, EMILIO; ROMANO, ELIDA ; RUDYK, ROXANA ; CATALÁN, C. A. N. ; BRANDAN, SILVIA A.

SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY.

PERGAMON-ELSEVIER SCIENCE LTD

Lugar: Amsterdam; Año: 2012 vol. 97 p. 202 - 208

1386-1425

We have studied and characterized the structural and vibrational properties of 4-hydroxy-3-(3-methyl-2-butenyl) acetophenone, isolated from Senecio nutans Sch. Bip. (Asteraceae) by infrared and Raman spectroscopies in the solid phase. The Density Functional Theory (DFT) method together with Pople’s basis set show that seven stable molecules for the compound have been theoretically determined in the gas phase and that only two conformations probably are present in the solid phase. The harmonic vibrational wavenumbers for the optimized geometry were calculated at B3LYP/6-31G*and B3LYP/6-311++G** levels. For a complete assignment of the vibrational spectra, DFT calculations were combined with Pulay´s Scaled Quantum Mechanics Force Field (SQMFF) methodology in order to fit the theoretical wavenumber values to the experimental ones. Then, a complete assignment of all the observed bands in the vibrational spectra was performed. The natural bond orbital (NBO) study reveals the characteristics of the electronic delocalization of the two stable structures, while the corresponding topological properties of electronic charge density are analysed by employing Bader’s Atoms in the Molecules theory (AIM).