Title of article :
Polarization IR spectra of the hydrogen bond in 1-naphthylacetic
and 2-naphthylacetic acid crystals: H/D isotopic effects.
Temperature and polarization effects
Author/Authors :
Henryk T. Flakus*، نويسنده , , Micha? Che?mecki، نويسنده ,
Issue Information :
روزنامه با شماره پیاپی سال 2004
Abstract :
This paper deals with experimental studies and with the quantitative interpretation of the polarized IR crystalline spectra of
1-naphthylacetic and 2-naphthylacetic acid. The spectra were measured in the nO–H and in the nO–D band frequency ranges, at the
temperatures of 298 and 77 K. The intensity distribution in the bands was quantitatively reproduced on the basis of the strong-coupling
model, when assuming that the isolated (COOH)2 and (COOD)2 cycles were the source of the spectral properties of the crystals. Such
approach appeared to be sufficient for explaining most of the isotopic and the temperature effects in the spectra. A vibronic mechanism,
promoting the symmetry forbidden transition in the IR, for the totally symmetric proton stretching vibrations in centrosymmetric hydrogen
bond dimers, was found to be of a considerably minor importance, when compared with analogous spectral properties of arylcarboxylic acid
crystals. Also no Fermi resonance impact on the nO–H band shape was identified in the 1-naphthylacetic and 2-naphthylacetic acid crystal
spectra. These effects were ascribed to weakening of electronic couplings between the hydrogen bonds and the phenyl rings, due to the
separation of these molecular fragments by methylene groups in 1-naphthylacetic and 2-naphthylacetic acid molecules.
q 2004 Elsevier B.V. All rights reserved
Keywords :
Hydrogen bond , Strong-coupling model , Polarization IR spectra , Model calculations , Linear dichroismeffects , Temperature effects , Fermi resonance , Band shape analysis , Molecular crystals , H/D isotopic self-organization effects
Journal title :
Journal of Molecular Structure
Journal title :
Journal of Molecular Structure