Acta Chim. Sinica ›› 2018, Vol. 76 ›› Issue (4): 298-302.

Article

温控近红外光谱用于胺类化合物氢键相互作用研究

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 天津化学化工协同创新中心 天津 300071
• 投稿日期:2018-01-03 发布日期:2018-03-05
• 通讯作者: 邵学广 E-mail:xshao@nankai.edu.cn
• 基金资助:

项目受国家自然科学基金（Nos.21475068和21775046）资助.

Temperature Dependent Near Infrared Spectroscopy for Understanding the Hydrogen Bonding of Amines

Zhu Xuewei, Cui Xiaoyu, Cai Wensheng, Shao Xueguang

1. Research Center for Analytical Sciences, College of Chemistry, Nankai University, Tianjin Key Laboratory of Biosensing and Molecular Recognition, State Key Laboratory of Medicinal Chemical Biology, Collaborative Innovation Center of Chemical Science and Engineering(Tianjin), Tianjin 300071
• Received:2018-01-03 Published:2018-03-05
• Contact: 10.6023/A18010003 E-mail:xshao@nankai.edu.cn
• Supported by:

Project supported by the National Natural Science Foundation of China (Nos. 21475068 and 21775046).

Temperature dependent near-infrared (NIR) spectroscopy has been developed for structural analyses, especially for the study of hydrogen bonding, due to the distinct influence of temperature on both intra-and inter-molecular interactions. In this work, the hydrogen bonding of primary aliphatic amines (amylamine, hexylamine and heptylamine) were studied using the NIR spectra measured from 25 to 80℃ with a step of 5℃. Continuous wavelet transform (CWT) was applied to enhance the resolution of the NIR spectra, and independent component analysis (ICA) was adopted for analyzing the temperature effect. High resolution spectra were obtained by CWT, from which the peaks of free and hydrogen-bonded NH groups can be identified. The results obtained by ICA show that three independent components (ICs) can be obtained, corresponding to the spectral information of the free, linearly and cyclically hydrogen-bonded NH groups, respectively. Therefore, with the reconstructed spectra from the three ICs, the variation of the three forms of NH groups with temperature can be analyzed. When temperature increases, the hydrogen-bonded NH groups transform into the free form, and the cyclic form dissociates through the linear form. Furthermore, NIR spectra of the amines in carbon tetrachloride (CCl4) solution were measured at 25℃ in the concentration range of 0.1~1.0 mol/L. The three ICs can also be obtained by ICA from the spectra after CWT. From the variation of the ICs with concentration, it was shown that NH groups in the amines prefer to be linearly aggregated at low concentration, but the cyclic aggregation increases with the increase of concentration. In addition, a comparison was performed on the results obtained by ICA from the spectra of the three amines measured at different temperatures. The result shows that there is no obvious difference for the temperature effect of the three amines, the variation of the three forms of NH groups with temperature, however, is different. With the increase of the carbon chain length, the variation of free and cyclically hydrogen-bonded NH group slows down, but there is a slight increase for the change rate of linearly hydrogen-bonded NH group. Therefore, temperature dependent near-infrared (NIR) spectroscopy may provide a new tool for studying the hydrogen bonding in liquid and solution samples with the help of chemometric calculations. The method may be promising for analyzing the complicated interactions in bio-systems, particularly the hydrogen bonding or inter-and intra-molecular interactions.