Conformational stability of allylbenzene: a combined study by dispersed fluorescence spectroscopy and quantum chemistry calculation

Panja, Sujit Sankar ; Chakraborty, Tapas (2003) Conformational stability of allylbenzene: a combined study by dispersed fluorescence spectroscopy and quantum chemistry calculation The Journal of Chemical Physics, 118 (14). Article ID 6200. ISSN 0021-9606

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Official URL: http://scitation.aip.org/content/aip/journal/jcp/1...

Related URL: http://dx.doi.org/10.1063/1.1559482

Abstract

Two conformational isomers of allylbenzene are identified in a supersonic free jet expansion by use of laser-induced fluorescence excitation and dispersed fluorescence spectroscopy. With the aid of the predictions of ab initio quantum chemistry calculations at the MP2 level for a series of extended basis sets[6-311+G(d,p), 6-311++G(d,p), and cc-pVTZ], the major species of the electronic spectrum is shown to be an eclipsed conformer in which the allyl group is oriented perpendicular to the plane of the benzene ring and a terminal hydrogen atom of the ethylene moiety is poised nearly above the aromatic π electrons. The minor species is identified as an internal rotational isomer that is obtained by rotating the ethylene group about the Cα–Cβ bond by 120° from the eclipsed configuration. This predicted order of conformational preference is reversed for calculations at relatively low levels of theory: MP2/6-31G(d,p), HF/6-311++G(d,p), HF/6-31G(d,p), and B3LYP/6-31G(d,p). The relative intensities of the vibronically induced nontotally symmetric and totally symmetric transitions are significantly different in the electronic spectra of the two conformers.

Item Type:Article
Source:Copyright of this article belongs to American Institute of Physics.
ID Code:100564
Deposited On:06 Dec 2016 12:07
Last Modified:06 Dec 2016 12:07

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