Department of Physics, Dumlupınar University, 43100 Kütahya, Turkey.
Spectrochim Acta A Mol Biomol Spectrosc. 2011 Nov;82(1):504-12. doi: 10.1016/j.saa.2011.07.089. Epub 2011 Aug 4.
FT-IR and FT-Raman spectra of 5-methoxysalicylic acid (5MeOSA) have been experimentally reported in the region of 4000-10 cm(-1) and 4000-50 cm(-1), respectively. The optimized geometric parameters, conformational equilibria, normal mode frequencies and corresponding vibrational assignments of 5MeOSA (C(8)H(8)O(4)) are theoretically examined by means of B3LYP hybrid density functional theory (DFT) method together with 6-31++G(d,p) basis set. Furthermore, reliable vibrational assignments have made on the basis of potential energy distribution (PED) calculated and the thermodynamics functions, highest occupied and lowest unoccupied molecular orbitals (HOMO and LUMO) of 5MeOSA have been predicted. Calculations are employed for different conformations of 5MeOSA, both in gas phase and in solution. Solvent effects are investigated using chloroform and dimethylsulfoxide. All results indicate that B3LYP method is able to provide satisfactory results for predicting vibrational frequencies and the structural parameters, vibrational frequencies and assignments, IR and Raman intensities of 5MeOSA are solvent dependent.
已实验报道了 5-甲氧基水杨酸（5MeOSA）在 4000-10 cm(-1) 和 4000-50 cm(-1) 区域的傅立叶变换红外（FT-IR）和傅立叶变换拉曼（FT-Raman）光谱。通过 B3LYP 杂化密度泛函理论（DFT）方法结合 6-31++G(d,p)基组，对 5MeOSA（C(8)H(8)O(4)）的优化几何参数、构象平衡、正则振动频率和相应的振动归属进行了理论研究。此外，还根据计算的势能分布（PED）和热力学函数，对 5MeOSA 的最高占据和最低未占据分子轨道（HOMO 和 LUMO）进行了预测。对 5MeOSA 的不同构象进行了计算，包括气相和溶液相。使用氯仿和二甲亚砜研究了溶剂效应。所有结果表明，B3LYP 方法能够为预测 5MeOSA 的振动频率和结构参数、振动频率和归属、IR 和拉曼强度提供满意的结果，5MeOSA 的溶剂依赖性。
