Department of Physics, A.A. Government Arts College, Musiri 621 211, Tamil Nadu, India.
Spectrochim Acta A Mol Biomol Spectrosc. 2013 Apr 15;107:347-58. doi: 10.1016/j.saa.2013.01.029. Epub 2013 Jan 30.
The FT-IR and FT-Raman vibrational spectra of 2,4-dichloro-5-nitropyrimidine (DCNP) and 4-methyl-2-(methylthio)pyrimidine (MTP) have been recorded in the range 4000-400 and 3600-50 cm(-1), respectively. A detailed vibrational spectral analysis has been carried out and assignments of the observed fundamental bands have been proposed on the basis of peak positions and relative intensities. The optimized molecular geometry and vibrational frequencies in the ground state are calculated using density functional B3LYP method with 6-31+G(d,p) and 6-311++G(d,p) basis set combinations. With the help of specific scaling procedures, the observed vibrational wavenumbers in FT-IR and FT-Raman spectra are analyzed and assigned to different normal modes of the molecules. The predicted first hyperpolarizability reveals that the molecules are an attractive object for future studies of non-linear optical properties. And also HOMO-LUMO energy gap explains the eventual charge transfer interaction taking place within the molecules. UV-vis spectral analysis of the title compounds has been researched by theoretical calculations. The frontier orbital energies, absorption wavelengths (λ), oscillator strengths (f) and excitation energies (E) studied using TD-DFT (B3LYP) with 6-311++G(d,p) basis set are calculated in this work.
已在 4000-400 和 3600-50 cm(-1) 范围内记录了 2,4-二氯-5-硝基嘧啶 (DCNP) 和 4-甲基-2-(甲硫基)嘧啶 (MTP) 的 FT-IR 和 FT-Raman 振动光谱。进行了详细的振动光谱分析，并根据峰位置和相对强度提出了观察到的基本带的分配。使用密度泛函 B3LYP 方法，使用 6-31+G(d,p) 和 6-311++G(d,p) 基组组合，在基态下计算了优化的分子几何形状和振动频率。借助特定的缩放程序，分析了 FT-IR 和 FT-Raman 光谱中观察到的振动波数，并将其分配给分子的不同正则模式。预测的第一超极化率表明，这些分子是未来研究非线性光学性质的有吸引力的对象。而且 HOMO-LUMO 能隙解释了分子内部发生的最终电荷转移相互作用。通过理论计算研究了标题化合物的 UV-vis 光谱分析。使用 TD-DFT (B3LYP) 与 6-311++G(d,p) 基组计算了前沿轨道能量、吸收波长 (λ)、振子强度 (f) 和激发能 (E)。
