— —   Electronic Spectra of Phenyl-, 3-Pyridyl-, Furfuryl-, and 2-Theinyl-Imino Derivatives of Thiazole: Molecular Orbital Treatment ADEL A. MOHAMED, MAHER M. HAMED Chemistry Department, Faculty of Science, Cairo University, Egypt Received 16 April 1997; revised 18 August 1997; accepted 15 September 1997 ABSTRACT: The electronic spectra of phenylmethylene, 3-pyridylmethylene, furfurylmethylene, and theinylmethylene derivatives of 2-aminothiazole have been investigated. Gaussian analysis for the spectra indicates the existence of four electronic transitions in the 350  220 nm region. Geometry optimization using AM1 method followed by INDOS-CI calculations was carried out. The results confirmed the absence of n  * Ž . transitions. The coefficients of configuration interaction CI wave functions defined the Ž . type of electronic transitions, which are of major charge transfer CT character. The anticonformer is the predominant one. The gap energies of the studied compounds are of the same order, which indicates that their reactivities are expected to be the same.  1998 John Wiley & Sons, Inc. Int J Quant Chem 66: 415423, 1998 Key words: Spectra; MO calculations; INDOS-CI; thiazoles; geometry optimization Introduction chiff bases have an important role in bio- S chemistry. They occur in rhdopsin, the visual pigment extracted from rod cells. In vitro an- tiplatelet activity of several imines and in vivo  antithrombatic were reported 1 . The electronic structure, spectral properties, and the energetics of Correspondence to:M. M. Hamed. interaction between the different subsystems of   some Schiff bases were investigated 2, 3 . The thiazole derivatives have a biological activity, e.g.,    carcinogenic 4  6 , potential fungicides 7 , and   industrial, e.g., corrosion inhibitors 8, 9 , their importance due to the presence of —C—S=C— or N—C—S— moiety. We aim to prepare and inves- tigate some new Schiff bases containing thiazole ring together with six- and five-member hetero- cyclic rings to throw light on the electronic proper- Ž ties structure, stable conformer, energetics and ( ) International Journal of Quantum Chemistry, Vol. 66, 415 423 1998  1998 John Wiley & Sons, Inc. CCC 0020-7608 / 98 / 060415-09