COMPLETE EXPERIMENTAL AND THEORETICAL INVESTIGATION OF THE

ANTIMICROBIAN DRUG 5-3-PYRIDIL METHYLIDEN-THIAZOLIDIN-2-THIN-4-ONA

Maria Baias1, A.Pirnau1, V.Chis1, M.Vasilescu1, O.Cozar1, O.Oniga2

1Babeş-Bolyai University, Faculty of Physics, Kogălniceanu 1, RO-400084 Cluj-Napoca, Romania

2Department of Pharmaceutical Chemistry, Faculty of Pharmacy, UMF “Iuliu Haţieganu”, Cluj Napoca

The title molecule (5-3PMTT) was recently synthesized at the Department of Pharmaceutical Chemistry, UMF "Iuliu Haţeganu" Cluj-Napoca and it was shown to be a very efficient antibiotic, with the advantage of a low bacterial resistance, compared to other common antibiotics. Due to its interesting properties it is worth to investigate the structure and properties of this molecule.

The molecular vibrations of 5-3PMTT were investigated in polycrystalline sample, at room temperature, by Fourier Transform Infrared Spectroscopy (FT-IR) and FT-Raman 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. All the possible conformers and tautomers of 5-3PMTT have been studied and analyzed by theoretical methods.

The vibrational properties of the 5-3PMTT molecule have been computed using DFT calculations at B3LYP and BLYP levels of theory using the standard 6-31G(d) basis set. The vibrational frequencies were assigned to experimental Raman and IR bands, and a very good correlation between the experimental and theoretical vibrational data was achieved.

The 1H and 13C NMR spectra of 5-3PMTT were obtained in DMSO solution and they were also calculated using the GIAO (Gauge-Including Atomic Orbitals) method implemented in the Gaussian package. Again, a very good correlation was found between experimental and theoretical NMR data and this allows us to validate the calculated structure and geometrical parameters of the molecule.

References

1.  V. Chis, Molecular and vibrational structure of 2,4-dinitrophenol: FT-IR, FR-Raman and quantum chemical calculations, Chemical Physics, 300, 1-11, 2004

2.  A. Yu. Kobitski, R. Scholz, D. R. T. Zahn, Theoretical studies of the vibrational properties of the 3,4,9,10-perylene tetracarboxylic dianhydride (PTCDA) molecule, Journal of Molecular Structure (Theochem), 625, 39-46, 2003