利用共振拉曼光谱鉴别茶多酚类分子的可行性研究  

Resonance raman spectral fingerprints of polyphenolic compounds in tea

作　　者：赵欣怡 何少贵 冯施施 梁万珍[2] ZHAO Xin-yi;HE Shao-gui;FENG Shi-shi;LIANG Wan-zhen(Office of Academic Research,Xiamen Huaxia University,Xiamen 361005,China;College of Chemistry and Chemical Engineering,Xiamen University,Xiamen 361005,China)

机构地区：[1]厦门华厦学院科研处,福建厦门361005 [2]厦门大学化学与化工学院,福建厦门361005

出　　处：《分子科学学报》2022年第2期145-153,共9页Journal of Molecular Science

基　　金：国家自然科学基金资助项目(21833006)。

摘　　要：本文从理论上探究是否可以利用共振拉曼光谱(RRS)来鉴别儿茶素类物质中的4种主要成分:EC,EGC,ECG和EGCG,并研究这些物质的微观结构信息和指纹特征谱.首先通过比较计算和实验测得的常规拉曼光谱确认了分子的构型;然后利用含时密度泛函理论(TD-DFT)计算了分子的紫外-可见(UV-Vis)吸收光谱,进而利用含时相关函数方法计算了与主要吸收峰对应的RRS,后者计算中其所需的几何和电子结构信息由(TD-)DFT提供.结果显示:虽然EC和EGC、ECG和EGCG二者在结构上仅仅只存在1个酚羟基的差别,但它们的RRS存在明显不同的指纹特征;现实中人们可以用不同频率的激光选择性地激发儿茶素类物质来获得RRS,以期鉴别儿茶素类物质.Due to its advantages such as ease of use,simple sample preparation and low water interference,Raman spectroscopy(RS)has been widely used to study the molecular structures and dynamics,and to identify the isomers as well.However,the low signal-to-noise ratio in normal Raman spectral(NRS)signals limits its applications.Resonance RS(RRS)has several advantages over the NRS,for example,RRS can provide much higher sensitivity and selectivity.This paper aims to explore the possibility of applying RRS to identify the Catechins,the major polyphenolic compounds in green tea,and to find the spectroscopic fingerprints which can be used to distinguish the Catechins.The four major compounds of Catechins:EC,EGC,ECG and EGCG,have been studied.Their optimal geometrical conformations were firstly determined by comparing the calculated and experimentally-measured NRS.Then,their UV-Vis absorption spectra were calculated by the time-dependent density functional theory(TD-DFT),and the RRS were calculated by the time-dependent correlation function approach,in which the required molecular geometrical and electronic structural parameters were obtained by(TD-)DFT calculations.The calculated RRS demonstrate significantly different spectral lineshapes although there are slight geometrical differences between ECG and EGCG,and between EC and EGC.One can selectively excite the compounds to obtain the RRS signals.This work recommends to use RRS technique to distinguish the Catechins,which can solve the identification problems caused by the weak NRS signals.

关 键 词：儿茶素类分子 常规和共振Raman光谱 UV-Vis吸收光谱 电子结构 DFT/TDDFT计算 

分 类 号：O644[理学—物理化学]