INQUINOA   21218
INSTITUTO DE QUIMICA DEL NOROESTE
Unidad Ejecutora - UE
artículos
Título:
Theoretical and experimental vibrational spectrum study of 4-hydroxybenzoic acid as monomer and dimmer
Autor/es:
S. A. BRANDÁN; F. MÁRQUEZ; M. MONTEJO; J. J. LÓPEZ GONZÁLEZ; A. BEN ALTABEF
Revista:
SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY.
Editorial:
PERGAMON-ELSEVIER SCIENCE LTD
Referencias:
Año: 2010 vol. 75 p. 1422 - 1434
ISSN:
1386-1425
Resumen:
Theoretical calculations on the molecular geometry and the vibrational spectrum of 4-hydroxybenzoic
acid were carried out by the Density Functional Theory (DFT/B3LYP) method. In addition, IR and Raman
spectra of the 4-hydroxybenzoic acid in solid phase were newly recorded using them in conjunction the
experimental and theoretical data (including SQM calculations), a vibrational analysis of this molecular
specie was accomplished and a reassignment of the normal modes corresponding to some spectral bands
was proposed. The geometries of monomers and dimers in gas phase were optimized using the DFT B3LYP
method with the 6-31G*, D95** and 6-311++G** basis sets. Also, both the vibrational spectra recorded
and the results of the theoretical calculations show the presence of one stable conformer for the 4-
hydroxybenzoic acid cyclic dimer. The B3LYP/6-31G* method was used to study the structure for cyclic
dimer of 4-hydroxybenzoic acid and for a complete assignment our results were compared with results
of the cyclic dimer of benzoic acid. A scaled quantum mechanical analysis was carried out to yield the
best set of harmonic force constants. The formation of the hydrogen bond was investigated in terms of
the charge density by the AIM program and by the NBO calculations.
© 2010 Elsevier