摘要： 应用太赫兹时域光谱系统（THz-TDS）获取了两种互为异构体的糖类D-(+)-葡萄糖和D-(-)-果糖的太赫兹吸收谱，发现D-(+)-葡萄糖和D-(-)-果糖在0.3～1.72 THz频段内太赫兹吸收峰位存在明显区别，可以由1.41和1.66 THz两个吸收峰位鉴别D-(+)-葡萄糖和D-(-)-果糖。为研究D-(+)-葡萄糖太赫兹光谱吸收峰形成机理，首先构建了D-(+)-葡萄糖的单分子构型，采用密度泛函理论中的B3LYP泛函，利用Gaussian09完成对D-(+)-葡萄糖单分子构型的结构优化与频率计算。将量子化学计算结果与实验谱对比发现，基于D-(+)-葡萄糖单分子构型的量子化学计算结果与实验谱差异较大。然后构建了D-(+)-葡萄糖晶胞构型，采用广义梯度近似中的PBE泛函，利用CASTEP软件完成对D-(+)-葡萄糖晶胞构型的结构优化与频率计算。将量子化学计算结果与实验谱对比发现，基于D-(+)-葡萄糖晶胞构型的量子化学计算结果与实验谱较为吻合。D-(+)-葡萄糖晶胞构型量子化学计算时，因较为全面的考虑了分子间的氢键及范德华力的作用，说明D-(+)-葡萄糖在1.41 THz处吸收峰的形成为分子间弱相互作用。其次通过Materials Studio 2017软件指认了D-(+)-葡萄糖在1.41 THz吸收峰处的振转模式，发现D-(+)-葡萄糖在1.41 THz吸收峰主要是分子之间的相互作用，进一步说明D-(+)-葡萄糖在1.41 THz处的吸收峰主要是分子间的弱相互作用。在量子化学计算结果的基础上利用Multiwfn软件对D-(+)-葡萄糖晶胞进行RDG计算，利用VMD软件对D-(+)-葡萄糖晶胞中分子间的弱相互作用的类型、位置和强度进行可视化研究。研究结果表明，利用太赫兹时域光谱技术能够敏锐地感知糖类物质结构的细微变化，并能够正确鉴别其同分异构体。
关键词：太赫兹时域光谱；D-(+)-葡萄糖；D-(-)-果糖；量子化学
Abstract：In this paper, the terahertz time-domain spectroscopy system (THz-TDS) was used to obtain the terahertz absorption spectra of two isomers of sugars D-(+)-glucose and D-(-)-fructose, and found that D-(+)-glucose and D-(-)-fructose have obvious differences in the terahertz absorption peak positions in the 0.3~1.72 THz frequency band. D-(+)-glucose and D-(-)-fructose can be distinguished by the two absorption peak positions of 1.41 and 1.66 THz. In order to study the formation mechanism of the absorption peak of D-(+)-glucose terahertz spectrum, the unimolecule configuration of D-(+)-glucose was first constructed, and the B3LYP functional in density functional theory was used to complete the D- (+)-Glucose unimolecule configuration optimization and frequency calculation. It is found that the quantum chemistry calculation results based on the D-(+)-glucose unimolecule configuration are quite different from the experimental spectrum. Then the D-(+)-glucose crystal structure configuration was constructed, and the generalized gradient was used to approximate the PBE functional in GGA. The structure optimization and frequency calculation of the D-(+)-glucose crystal structure configuration were completed using CASTEP software. It is found that the quantum chemistry calculation results based on the D-(+)-glucose crystal structure configuration are more consistent with the experimental spectrum. In the quantum chemistry calculation of the D-(+)-glucose crystal structure configuration, the hydrogen bond between the molecules and the effect of van der Waals forces are considered comprehensively, indicating that the absorption peak of D-(+)-glucose at 1.41 THz is formed as a molecule Weak interaction between. Secondly, the vibration mode of D-(+)-glucose at 1.41 THz absorption peak was identified by Materials Studio 2017 software, and it was found that the absorption peak of D-(+)-glucose at 1.41 THz was mainly the interaction between molecules, which further explained The absorption peak of D-(+)-glucose at 1.41 THz is mainly the weak interaction between molecules. Based on the quantum chemistry calculation results, use Multiwfn software to perform RDG calculation on D-(+)-glucose crystal structure, and use VMD software to determine the type, position and intensity of weak interaction between molecules in D-(+)-glucose crystal structure Conduct visualization research. The research results show that terahertz time-domain spectroscopy technology can keenly perceive the subtle changes in the structure of carbohydrates and correctly identify its isomers.
燕 芳，张俊林，毛莉程，刘同华，金伯阳. 基于太赫兹辐射的糖类异构体信息提取方法研究[J]. 光谱学与光谱分析, 2022, 42(01): 26-30.
YAN Fang, ZHANG Jun-lin, MAO Li-cheng, LIU Tong-hua, JIN Bo-yang. Research on Information Extraction Method of Carbohydrate Isomers Based on Terahertz Radiation. SPECTROSCOPY AND SPECTRAL ANALYSIS, 2022, 42(01): 26-30.
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