温度扰动下氯化胆碱/丙三醇溶液的二维红外光谱研究  

Two-Dimensional Infrared Spectroscopic Study of Choline Chloride/Glycerin Solution Disturbed by Temperature

作　　者：张雁东 吴晓静 李子轩 程龙玖[2] ZHANG Yan-dong;WU Xiao-jing;LI Zi-xuan;CHENG Long-jiu(School of Chemistry and Chemical Engineering,Hefei University of Technology,Hefei 230009,China;College of Chemistry&Chemical Engineering,Anhui University,Hefei 230601,China)

机构地区：[1]合肥工业大学化学与化工学院,安徽合肥230009 [2]安徽大学化学化工学院,安徽合肥230601

出　　处：《光谱学与光谱分析》2023年第10期3047-3051,共5页Spectroscopy and Spectral Analysis

基　　金：国家自然科学基金项目(21873001)资助。

摘　　要：随着绿色化学的要求,更多科研工作者们致力于绿色环保的低共熔溶剂(DES)研究上。氯化胆碱类DES具有无毒无污染且容易制备的特性,已被应用于许多不同的领域。以氯化胆碱(Choline chloride,ChCl)和丙三醇(Glycerine,Gly)形成的DES为研究对象。对比ChCl,Gly和ChCl/Gly的红外光谱图,发现NC_(4)和O—H发生了红移以及特征峰的合并和消失,这些都表明ChCl/Gly通过N—H_(Ch)^(+)…Cl^(-)和Cl^(-)…H—O Gly的方式形成DES。为了探究不同温度下DES变化情况,以温度为外扰测试25~135℃下ChCl/Gly的红外光谱数据,对比这些数据发现不同温度下NC_(4)和O—H光谱峰的强度、宽度和位置都发生了一定程度的改变,但是这些特征峰都是宽峰具有重叠现象,很难通过一维光谱分析,采用二维红外光谱(2D-IR)可以对复杂溶液体系进行更好的图谱分析,探究其形成机理和分子间结构。对ChCl/Gly中NC_(4)和O—H特征峰随温度变化的数据进行2D-IR分析,获得动态变化顺序,推测溶液中不同的分子团簇。研究发现25~65℃时O—H在3539、3400、3380和3177 cm^(-1)有四个自动峰,NC_(4)也出现不同的自动峰,这些峰可归属于ChCl/Gly、ChCl/(Gly)2、ChCl/(Gly)3;在65~105℃时O—H在3539、3400和3380 cm^(-1)有三个自动峰,NC_(4)有相应的变化,这些峰可归属于ChCl/Gly和ChCl/(Gly)2;在105~135℃时O—H只在3380 cm^(-1)有一个强自动峰,NC_(4)也只出现一个自动峰,可归属于ChCl/Gly。通过2D-IR分析得出随温度上升溶液中分子团簇解离成更稳定的结构,为了验证这一结论和探究不同团簇分子间Cl^(-)作为桥梁形成N—H_(Ch)^(+)…Cl^(-)和Cl^(-)…H—O Gly具体连接方式。采用密度泛函理论(DFT)在B3LYP/6-311G++(2d,p)理论水平上进行构型几何优化,计算出相关的热力学数据,证实了ChCl/Gly中不同分子团簇存在的可能性。研究表明2D-IR和密度泛函理论计算相结合,能够很好地用于分析DES中不同分子团�With the requirements of green chemistry,more researchers are committed to studying green eutectic solvents(DES).Choline chloride eutectic solvent(DES)has been used in many fields because of its non-toxic,pollution-free and easy preparation.DES formed by choline chloride(ChCl)and glycerol(Gly)was studied in this paper.Comparing the infrared spectra of ChCl,Gly and ChCl/Gly,it was found that NC4 and O—H had red-shift and the combination and disappearance of characteristic peaks,which all indicated that ChCl/Gly formed DES through N—H_(Ch)^(+)…Cl^(-)and Cl^(-)…H—O Gly.In order to explore the changes of DES at different temperatures,the infrared spectral data of ChCl/Gly at 25~135℃were tested with temperature as an external disturbance.It was found that the intensity,width and position of NC_(4)and O—H spectral peaks changed to a certain extent at different temperatures,but these characteristic peaks were all wide peaks with overlapping phenomenon.It is difficult to conduct one-dimensional spectral analysis,but two-dimensional infrared spectroscopy(2D-IR)can better analyze the complex solution system and explore its formation mechanism and intermolecular structure.2D-IR analysis was performed on the data of NC_(4)and O—H characteristic peaks in ChCl/Gly as a function of temperature to obtain the dynamic change sequence and predict the different molecular clusters in the solution.The results Three automatic O—H peaks at 3539,3380 and 3177 cm^(-1)at 25~65℃.Different automatic peaks of NC_(4)also appear,which can be attributed to ChCl/Gly,ChCl/(Gly)2 and ChCl/(Gly)3.At 65~105℃,O—H has two automatic peaks at 3539,3380 and 3400 cm^(-1),and NC_(4)has corresponding changes,which can be attributed to ChCl/Gly and ChCl/(Gly)2.At 105~135℃,O—H only had a strong automatic peak at 3380 cm^(-1),and NC_(4)only had an automatic peak,attributed to ChCl/Gly.Through 2D-IR analysis,it is concluded that molecular clusters in the solution dissociate into a more stable structure with the rise of temperature.In

关 键 词：低共熔溶剂 二维红外光谱 氢键 密度泛函理论 

分 类 号：O645[理学—物理化学]