纤维素拉曼光谱的单体仿真方法研究  

Study on Monomer Simulation of Cellulose Raman Spectrum

作　　者：王新强[1,3] 储佩珠 熊伟 叶松[1,3] 甘永莹[1,3] 张文涛 李树 王方原[1,3] WANG Xin-qiang;CHU Pei-zhu;XIONG Wei;YE Song;GAN Yong-ying;ZHANG Wen-tao;LI Shu;WANG Fang-yuan(School of Optoelectronic Engineering,Guilin University of Electronic Technology,Guilin 541004,China;Guangxi Key Laboratory of Optoelectronic Information Processing,Hefei 230031,China;Anhui Institute of Optics and Fine Mechanics,Chinese Academy of Sciences,Guilin 541004,China;Key Laboratory of General Optical Calibration and Characterization of Chinese Academy of Sciences,Hefei 23003l,China)

机构地区：[1]桂林电子科技大学光电工程学院,广西桂林541004 [2]中国科学院安徽光学精密机械研究所,安徽合肥230031 [3]广西光电信息处理重点实验室,广西桂林541004 [4]中国科学院通用光学定标与表征技术重点实验室,安徽合肥230031

出　　处：《光谱学与光谱分析》2024年第1期164-168,共5页Spectroscopy and Spectral Analysis

基　　金：国家重点研发项目(2022YFB3901800);广西自然科学基金项目(桂科AD19245184);国家自然科学基金项目(41961050,41975033);中国科学院通用光学定标与表征技术重点实验室研究项目;广西光电信息处理重点实验室基金项目(GD18105,GD21105)。

摘　　要：纤维素是由葡萄糖组成的大分子多糖,是世界上最丰富、最便宜、最容易获得的天然聚合物。纤维素作为最古老最丰富的天然高分子在研究中备受关注,纤维素的可控性取决于其分子量、大小和结构,而拉曼光谱具有“指纹特性”,可以对不同的纤维素纤维进行鉴别,也能对历史老化的纺织纤维材料进行鉴别。然而纤维素作为大分子多糖对其做理论仿真较为困难,该研究提出采用基本单元模拟大分子光谱这一方案,使用纤维素单体仿真拉曼光谱来分析纤维素大分子的光谱性质。使用Gaussian 16软件基于密度泛函理论,在B3LYP/6-31g(d, p)的基组条件下,计算了不同外电场(-0.01-0.03 a.u.)下的纤维素单体的拉曼光谱,以及纤维素双链节的拉曼光谱。研究表明,在无外电场作用下,纤维素单体的拉曼光谱主要在449、 597、 842、 1 127、 1 361、 1 395和3 005 cm^(-1)处有特征峰,对其做振动分析,结果表明这些拉曼峰分别是由环(C6—C4—O20)伸缩振动、 C—C—H扭曲振动、环(C4—O20—C2)伸缩振动、糖苷键(C2—O1—C8)的伸缩振动、 CH_(2)的弯曲振动、 CH_(2)的弯曲振动、 CH_(2)的伸缩振动产生。通过与实验值比较,纤维素单体仿真拉曼光谱与天然纤维素的实测拉曼光谱相吻合,故可通过对纤维素单体的第一性原理计算来反映纤维素大分子的拉曼光谱特性。当外电场由负方向变为正方向且逐渐增大时,597 cm^(-1)对应的环C—C—H扭曲振动的振幅无明显变化,以无电场为基准,施加外电场时,振动能量减小光谱红移;1 127 cm^(-1)对应的糖苷键(C2—O1—C8)的伸缩振动振幅明显减小,光谱呈蓝移;CH_(2)的弯曲振动在1 395 cm^(-1)处的特征峰光谱呈蓝移,在1 361 cm^(-1)处产生的光谱先蓝移再红移又再次蓝移,推测是弯曲振动区域更容易受到骨架振动和环境变化的影响。对比纤维素单体与双链节拉曼光谱的差异,除单体明�Cellulose is a macromolecular polysaccharide composed of glucose,the most abundant,cheapest and easiest to obtain natural polymer in the world.Cellulose,as the oldest and most abundant natural polymer,has attracted much attention in research.The controllability of cellulose depends on its molecular weight,size and structure,and Raman spectroscopy has“fingerprint characteristics”,which can identify different cellulose fibers,as well as historical aging textile fiber materials.However,it is difficult to simulate cellulose as a macromolecular polysaccharide theoretically.In this study,we propose using the basic unit to simulate macromolecular spectrum,and use cellulose monomer to simulate Raman spectrum to analyze the spectral properties of cellulose macromolecules.In this paper,based on density functional theory,the Raman spectra of cellulose monomers and cellulose double links under different external electric fields(a.u.)were calculated under the basis set conditions of B3LYP/6-31g(d,p)using Gaussian 16 software.The study shows that the Raman spectrum of cellulose monomer has characteristic peaks at 449,597,842,1127,1361,1395 and 3005 cm^(-1)without the action of the external electric field.The vibration analysis shows that these Raman peaks are respectively composed of the ring(C6—C4—O20)stretching vibration,C—C—H twisting vibration,ring(C4—O20—C2)stretching vibration,glycosidic bond(C2—O1—C8)stretching vibration,CH_(2) bending vibration The expansion vibration of CH_(2) is generated.Compared with the experimental value,the simulated Raman spectrum of cellulose monomer is consistent with the measured Raman spectrum of natural cellulose,so the first principle calculation of cellulose monomer can reflect the Raman spectrum characteristics of cellulose macromolecules.When the external electric field changes from the negative direction to the positive direction and gradually increases,the amplitude of the C—C—H torsional vibration of the ring corresponding to 597 cm^(-1)has no obvious change.

关 键 词：纤维素 电场 拉曼光谱 

分 类 号：O657.37[理学—分析化学]