Analysis of vibrational spectra of some new E- and Z-4-arylidene-3-isochromanones

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Abstract

The solid and vapor phase IR and the solid phase Raman spectra of partially or fully resolved E- and Z-isomers of seven isochromanone derivatives were measured and analyzed with the aim of determining the differences in the vibrational behavior of the main rotational isomers. To aid spectral interpretation, quantum chemical and normal coordinate calculations were carried out for the 2′-furyl-substituted derivative, codenamed IK-14. The optimized molecular structures and corresponding force fields were calculated for four minimum energy configurations using the DFT/B3LYP/6-31* method. The vibrational frequencies and IR intensities were then calculated and fitted to the measured ones by the SQM force field approach. The calculations were highly successful in reproducing the frequencies and in clarifying the trends of changes brought about by cis-trans isomerism and other conformational changes. This resulted in a detailed vibrational assignment, and a common set of scale factors preferable for work with this type of molecules.

Original languageEnglish
Pages (from-to)53-59
Number of pages7
JournalVibrational Spectroscopy
Volume29
Issue number1-2
DOIs
Publication statusPublished - Jul 5 2002

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Keywords

  • Cis-trans isomerism
  • DFT force field
  • Isochromanones
  • Rotamers
  • Vibrational spectra

ASJC Scopus subject areas

  • Spectroscopy

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