Lasers and Spectroscopy Laboratory, Department of Physics, Banaras Hindu University, Varanasi 221 005, India.
Spectrochim Acta A Mol Biomol Spectrosc. 2013 Jul;111:242-51. doi: 10.1016/j.saa.2013.03.004. Epub 2013 Mar 28.
IR and Raman spectra of pyridine and pyridine-N-oxide have been recorded and analyzed. The optimized molecular geometries, APT charges and vibrational characteristics for benzene, pyridine, pyridine-N-oxide and their cations have been computed using DFT method. Due to attachment of O atom at N site or removal of electron all the modes are affected in magnitudes. However, significant changes are noticed in their IR intensities, Raman activities and depolarization ratios of the Raman bands in going from pyridine to its N-oxide or in going from neutrals to their cations. It is interesting to note that in going from benzene to benzene cation charge redistribution takes place to reduce the symmetry from D6h to D2h. The calculated frequencies have been correlated with the experimental frequencies for the pyridine and pyridine-N-oxide molecules.
已记录并分析了吡啶和吡啶-N-氧化物的红外和拉曼光谱。使用 DFT 方法计算了苯、吡啶、吡啶-N-氧化物及其阳离子的优化分子几何形状、APT 电荷和振动特性。由于在 N 位上附加 O 原子或去除电子，所有模式的幅度都受到影响。然而，从吡啶到其 N-氧化物或从中性到其阳离子的变化，其红外强度、拉曼活性和拉曼带的退偏比都有明显变化。有趣的是，从苯到苯阳离子，电荷重新分布以降低对称性从 D6h 到 D2h。计算频率与吡啶和吡啶-N-氧化物分子的实验频率相关联。
