Erdogdu Yusuf, Saglam Semran
Department of Physics, Ahi Evran University, 40040 Kirsehir, Turkey.
Department of Physics, Gazi University, 06100 Ankara, Turkey.
Spectrochim Acta A Mol Biomol Spectrosc. 2014 Nov 11;132:871-8. doi: 10.1016/j.saa.2014.04.074. Epub 2014 May 29.
We report a combined some (infrared, Raman and NMR) spectroscopic and quantum chemistry study on 7,8-Dihydroxy-4-Methylcoumarin molecule (78D4MC). The Raman and IR spectra of 78D4MC molecule were recorded and analyzed in the region 3500-50 cm(-1) and 4000-400 cm(-1), respectively. Potential energy scans were performed at the MMFF level of theory. All possible conformers, which are results at the MMFF level theory, were re-computed at the B3LYP functional with cc-pVDZ basis set. The optimized geometrical parameters, harmonic vibrational wavenumbers and NMR chemical shifts of the most stable conformer were calculated at the B3LYP/6-311G(d,p), cc-pVTZ and cc-pVQZ level in the proximity of the isolated molecule. DFT calculations were combined with Pulay's scaled quantum mechanics force field (SQMFF) methodology in order to fit the theoretical wavenumbers to the experimental ones.
我们报告了一项关于7,8 - 二羟基 - 4 - 甲基香豆素分子（78D4MC）的联合（红外、拉曼和核磁共振）光谱及量子化学研究。分别在3500 - 50 cm⁻¹和4000 - 400 cm⁻¹区域记录并分析了78D4MC分子的拉曼光谱和红外光谱。在MMFF理论水平上进行了势能扫描。对所有在MMFF理论水平下得到的可能构象异构体，使用cc - pVDZ基组在B3LYP泛函下重新计算。在孤立分子附近，在B3LYP/6 - 311G(d,p)、cc - pVTZ和cc - pVQZ水平下计算了最稳定构象异构体的优化几何参数、谐振动波数和核磁共振化学位移。为了使理论波数与实验波数拟合，将密度泛函理论（DFT）计算与普利（Pulay）的缩放量子力学力场（SQMFF）方法相结合。
