Premium
Phenylene vinylene oligomers studied by theoretical methods: Joint analysis of computational and x‐ray results of the configurational isomers of 1,4‐bis[2‐(3,4,5‐trimethoxyphenyl)ethenyl]benzene
Author(s) -
Wu Guang,
Jacobs S.,
Verbruggen M. G.,
Lenstra A. T. H.,
van Alsenoy C.,
Geise H. J.,
van Meervelt L.
Publication year - 1996
Publication title -
journal of computational chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.907
H-Index - 188
eISSN - 1096-987X
pISSN - 0192-8651
DOI - 10.1002/(sici)1096-987x(199608)17:10<1245::aid-jcc5>3.0.co;2-n
Subject(s) - chemistry , ab initio , computational chemistry , ab initio quantum chemistry methods , cis–trans isomerism , singlet state , structural isomer , molecule , benzene , crystallography , stereochemistry , excited state , atomic physics , organic chemistry , physics
The configurational isomers of 1,4‐bis[2‐(3,4,5‐trimethoxyphenyl)ethenyl]benzene have been investigated by ab initio and MOPAC‐AM1 semiempirical methods. The calculations were guided by and compared with single crystal X‐ray results of the trans, trans ‐isomer (taken from the literature) and of the cis,cis ‐isomer (reported here). Using 4‐21G‐based ab initio calculations, free state geometries, deviations from coplanarity, and barriers to rotation of the central and peripheral rings were evaluated. Such barriers were also enumerated for the solid state of the cis,cis ‐ and trans,trans ‐isomers. A single‐molecule cluster surrounded by point charges sufficed to rationalize observed solid state properties in the trans,trans ‐isomer, including the quasi‐free rotation of the central ring. A multimolecule cluster, however, was required to rationalize the restricted rotation of the rings in the cis,cis ‐isomer. MOPAC‐AM1 methods were used to calculate geometries and energies of rotameric forms on the singlet photoisomerization path cis,cis → cis,trans → trans,trans . Finally, UV absorption wavelengths and oscillator strengths were calculated and the electronic structure of the states discussed. © 1996 by John Wiley & Sons, Inc.