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Ab initio HF, DFT and experimental (FT-IR) investigation of vibrational spectroscopy of 3-(2-(4-isopropylpiperazin-1-yl)-2-oxoethyl)-6-(4-methoxybenzoyl)benzo[d]thiazol-2(3H)-one

2013    Tasal, Erol; Kumalar, Mustafa

FT-IR spectra was recorded for 3-(2-(4-isopropylpiperazin- 1 -yl)-2-oxoethyl)-6-(4-methoxybenzoyl) benzo [d]thiazol-2(3H)-one molecule (abbreviated as IOMBT) sample in solid state. Conformational analysis of IOMBT was performed to determine the most stable conformer. Potential energy curves of IOMBT were obtained performing a relaxed scan of D1-7 dihedral angels at B3LYP/6-311++G(d,p) level of theory. Geometrical parameters of these structures were optimized by using the same method. The molecular geometry of IOMBT was reoptimized at DFT(B3LYP) and HF methods using 6-311++G(d,p), 6-311+G(d), 6-311G(d,p), 6-311G(d) and 6-31++G(d,p) basis sets for the lowest energy conformer. The vibrational frequencies, IR intensities were calculated at DFT(B3LYP) and HF methods. The thermodynamic parameters (such as zero-point vibrational energy, E-HOMO, E-LUMO, thermal corrections to energy, enthalpy and Gibbs free energy, and entropy) have also been computed. The LUMO-HOMO energy gap of IOMBT shows that the energy gap reflects the chemical reactivity and the level of conductivity of the molecule. (C) 2012 Elsevier B.V. All rights reserved.