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FT Raman and DFT Study on a Series of All‐ anti Oligothienoacenes End‐Capped with Triisopropylsilyl Groups
Author(s) -
Malavé Osuna Reyes,
Hernández Víctor,
López Navarrete Juan T.,
Aragó Juan,
Viruela Pedro M.,
Ortí Enrique,
Suzuki Yoshitake,
Yamaguchi Shigehiro,
Henssler John T.,
Matzger Adam J.
Publication year - 2009
Publication title -
chemphyschem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.016
H-Index - 140
eISSN - 1439-7641
pISSN - 1439-4235
DOI - 10.1002/cphc.200900440
Subject(s) - homo/lumo , raman spectroscopy , molecular orbital , thiophene , chemistry , atomic orbital , computational chemistry , crystallography , stereochemistry , molecule , photochemistry , physics , organic chemistry , quantum mechanics , electron , optics
Herein, we study the π‐conjugational properties of a homologous series of all ‐anti oligothienoacenes containing four to eight fused thiophene rings by means of FT Raman spectroscopy and DFT calculations. The theoretical analysis of the spectroscopic data provides evidence that selective enhancement of a very limited number of Raman scatterings is related to the occurrence in these oligothienoacenes of strong vibronic coupling between collective ν(CC) stretching modes in the 1600–1300 cm −1 region and the HOMO/LUMO frontier orbitals (HOMO=highest occupied molecular orbital; LUMO=lowest unoccupied molecular orbital). The correlation of the Raman spectroscopic data and theoretical results for these all ‐anti oligothienoacenes with those previously collected for a number of all ‐syn oligothienohelicenes gives further support to the expectation that cross‐conjugation is dominant in heterohelicenes. Fully planar all ‐anti oligothienoacenes display linear π conjugation which seemingly does not reach saturation with increasing number of annulated thiophene rings in the oligomeric chain at least up to the octamer.