高等学校化学学报 ›› 2023, Vol. 44 ›› Issue (6): 20230017.doi: 10.7503/cjcu20230017

• 分析化学 • 上一篇    下一篇

近红外光谱用于低共熔溶剂中水结构的分析

王岩1,2, 蔡文生1,2, 邵学广1,2()   

  1. 1.南开大学化学学院分析科学研究中心, 天津市生物传感与分子识别重点实验室, 药物化学生物学国家重点实验室, 天津 300071
    2.物质绿色创造与制造海河实验室, 天津 300192
  • 收稿日期:2023-01-13 出版日期:2023-06-10 发布日期:2023-03-04
  • 通讯作者: 邵学广 E-mail:xshao@nankai.edu.cn
  • 基金资助:
    国家自然科学基金(22174075);天津市自然科学基金(20JCYBJC01480);南开大学中央高校基本科研业务费专项资金(63211019);物质绿色创造与制造海河实验室项目(ZYTS202105)

Understanding the Water Structures in Deep Eutectic Solvents by Near-infrared Spectroscopy

WANG Yan1,2, CAI Wengsheng1,2, SHAO Xueguang1,2()   

  1. 1.Research Center for Analytical Sciences,College of Chemistry,Tianjin Key Laboratory of Biosensing and Molecular Recognition,State Key Laboratory of Medicinal Chemical Biology,Nankai University,Tianjin 300071,China
    2.Haihe Laboratory of Sustainable Chemical Transformations,Tianjin 300192,China
  • Received:2023-01-13 Online:2023-06-10 Published:2023-03-04
  • Contact: SHAO Xueguang E-mail:xshao@nankai.edu.cn
  • Supported by:
    the National Natural Science Foundation of China(22174075);the Natural Science Foundation of Tianjin, China(20JCYBJC01480);the Foundation Research Funds for the Central Universities, Nankai University, China(63211019);the Program of Haihe Laboratory of Sustainable Chemical Transformations, China(ZYTS202105)

摘要:

采用近红外光谱技术研究了含水量(摩尔分数)在5%~95%范围内水结构对低共熔溶剂(DESs)的氢键网络结构的影响. 通过分析氯化胆碱与尿素混合后不同时间的近红外光谱, 发现了尿素—NH基团与氯化胆碱Cl-相互作用的光谱信息, 表明DESs熔点降低的原因主要是NH···Cl-氢键的形成. 通过分析不同含水量的DESs-水混合物的近红外光谱, 发现了水分子之间以及水分子与尿素中—NH和C=O基团相互作用的光谱信息, 表明水在DESs中主要以3种结构存在: 类大体积水、 与尿素C=O键合的水以及—NH分子间的桥连水. 类大体积水破坏DESs中NH···Cl-, 使体系的稳定性降低, 而尿素—NH分子间的桥连水和与C=O键合的水使体系的稳定性增加. DESs中3种水结构的相对比例与含水量有关, 含水量在40%~80%既能有效降低体系的黏度, 又能维持DESs的性质.

关键词: 近红外光谱, 低共熔溶剂, 氯化胆碱-尿素, 水结构

Abstract:

The hydrogen bond network structure of choline chloride/urea deep eutectic solvents(DESs)-water mixtures was studied in the range of 5%—95% water content by near infrared spectroscopy. Through the analysis of the near-infrared spectra after choline chloride and urea mixing, the spectral feature of the interaction between urea —NH group and choline chloride Cl- was found, indicating that the formation of NH···Cl- was the reason for the decrease of DESs melting point. Through the near-infrared spectrum analysis of DESs-water mixtures with different water contents, the spectral information of the interaction between water molecules and between water molecules and the —NH and C=O groups in urea was found. Water mainly exists in three kinds of structures, including the bulk water, the hydrated water with urea C=O and the bridge water connect —NH groups. The bulk water destroyed NH···Cl- in DESs, reducing the stability of the system, while the bridge water between urea —NH molecules and the hydrated water with urea C=O increase the stability of the system. The relative content of the three water structures in DESs is related to the water content. The water content of 40%—80% can not only effectively reduce the viscosity of the system, but also maintain the properties of DESs.

Key words: Near infrared spectroscopy, Deep eutectic solvent, Choline chloride/urea, Water structure

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