两种联苯酚类化合物的太赫兹时域光谱研究

利用太赫兹时域光谱技术获得了295 K时2,2′-二羟基联苯(2,2′-biphenol, 2BP)和4,4′-二羟基联苯(4,4′-biphenol, 4BP)在0.1~1.6 THz波段的光谱. 实验结果显示, 两种同分异构体在太赫兹频率范围内的吸收谱有显著的差异. 结合量子化学计算, 2BP中的两个羟基间能够形成分子内氢键, 在1.45 THz的运动模式初步判断为包含氢键在内的两个苯环的低频摆动.

Far-infrared Spectra of 2,2'-biphenol and 4,4'-biphenol Measured by Terahertz Time Domain Spectroscopy

The far-infrared spectra of 2,2′-biphenol(2BP) and 4,4′-biphenol(4BP) in the frequency range between 0.1 and 1.6 THz were measured by terahertz time-domain spectroscopy at 295 K. We observed distinct differences between the two isomers. 2BP has an absorption band at 1.45 THz while 4BP shows no peaks through all experimental frequency range. To investigate the relationship between the THz spectra and the low-energy modes of the molecules, quantum chemical calculations with full geometry optimizations and frequency analysis of the optimized structures were performed using the Gaussian 03 program package. The structure analyses with AM1 show that the hydroxyl groups in 2BP can form intramolecular hydrogen bond. The origin of the observed absorption at 1.45 THz is assigned to the low-frequency torsions of the two-phenyl rings which contain the hydrogen bond.