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A. Pirnau, V. Chis, O. Oniga, N. Leopold, L. Szabo, M. Baias, O. Cozar. Vibrational and DFT Study of 5-(3-Pyridyl-Methylidene)-Thiazolidine-2-Thione-4-One. Vibrational Spectroscopy, 48, pp. 289-296, 2008.

Abstract: The molecular vibrations of 5-(3-pyridyl-methylidene)-thiazolidine-2-thione-4-one (5-3-PMTT) were investigated by FT-IR, FT-Raman and
SERS spectroscopies. In parallel, quantum chemical calculations based on density functional theory (DFT) are used to determine the geometrical,
energetic and vibrational characteristics of the molecule. The three possible tautomers of 5-3-PMTT (thione, thiol and enol) have been analyzed by
theoretical methods and their relative stability is discussed. The vibrational spectrum of the solid state 5-3-PMTT compound has been assigned
based on DFT calculations at B3LYP level of theory using the standard 6-31G(d) basis set. The experimental vibrational bands were assigned to the
calculated normal modes and a very good correlation was achieved between the experimental and theoretical data. SERS spectra suggest an
important deformation of the adsorbed molecule on silver colloid surface; the six-membered ring is almost perpendicular while the thiazolidine
ring lies almost parallel to Ag colloid surface. The molecular electrostatic potential of the molecule has been calculated and used for predicting site
candidates of electrophilic attack.

Keywords: Methylidene–thiazolidine derivatives; FT-IR; FT-Raman; SERS; DFT

Posted by Vasile Chis


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