Journal of Computer Chemistry, Japan
Online ISSN : 1347-3824
Print ISSN : 1347-1767
ISSN-L : 1347-1767
Quantum Chemical Calculations on Conformations and Absorption Spectra of Azo Dyes Consisting of Thiophene and 5-Membered Rings
Yoshiya KOGOSumio TOKITAKichisuke NISHIMOTO
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2007 Volume 6 Issue 2 Pages 109-116

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Abstract

The bathochromicity of thiophene and thiazole azo dyes was studied by using quantum chemical calculations on azo compounds consisting of benzene, thiophene, furan, pyrrole, cyclopentadiene and their aza substituted rings. Conformational analyses at AM1, PM3 and B3LYP/6-31G* level of theory were performed to estimate the stable conformers of these compounds. The CNDO/S calculations including and excluding 3d-AOs on the sulfur atom confirmed that the 3d-AOs do not contribute to the bathochromicity of thiophene and thiazole azo dyes. The results of CNDO/S and TD-B3LYP/6-31+G* calculations on absorption spectra suggested that azo compounds with a 5-membered ring commonly absorb at longer wavelengths relative to the corresponding azobenzenes.

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© 2007 Society of Computer Chemistry, Japan
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