Two-Dimensional Correlation Raman Spectroscopic Analysis of CuCl2/DMF Solution Under Temperature Disturbance
WU Xiao-jing1, LI Zhi1, LI Zi-xuan1, LI Xing-xing1, CHENG Long-jiu2
1. School of Chemistry and Chemical Engineering, Hefei University of Technology, Hefei 230009, China
2. College of Chemistry and Chemical Engineering, Anhui University, Hefei 230601, China
Abstract：The spectroscopic study of the solution has always attracted the attention of chemists, but most of them are based on one-dimensional spectroscopy. There are many disadvantages, such as low resolution, greatly affected by the error, overlapping peaks are difficult to distinguish and so on. So that we cannot get the information we need clarification. These problems were well solved by the introduction of two-dimensional correlation spectroscopy. By correlation analysis and calculation of dynamic spectra under external disturbances, the overall change information of spectral intensity can be obtained, which can significantly improve the resolution of one-dimensional spectroscopy and the separation degree of overlapping peaks. It has unique advantages in judging the response order of different functional groups under specific external disturbance and studying the weak intermolecular and intramolecular interactions. In this article, two-dimensional correlation Raman spectroscopy and theoretical calculation have been combined to the analysis of the micro clusters in solution. The target solution (pure DMF and CuCl2/DMF solution of 0.84 mol·L-1) was studied by micro confocal laser Raman spectrometer. The results have shown that, in the range of C—N bond stretching vibration band, due to the addition of CuCl2, thestrength of the characteristic peak decreases greatly, and the peak width becomes large. Furthermore, it could be found that there is a new peak at 1 115 cm-1, With the rise of temperature, the strength of stretching vibration peak decreases gradually, and the peak shape becomes slow. It is concluded that different types of micro clusters have different sensitivity to temperature with the help of moving-window two-dimensional Raman (MW2D Raman) spectroscopy. in addition, with the increase of temperature, they transform into each other and change at different rates. In order to obtain the essence of the micro cluster movement in the solution, the target solution was analyzed by two-dimensional Raman(2D Raman)spectroscopy with temperature as the external disturbance. It is found that the addition of Cu2+ makes the solution system more complex. In addition to the cluster structure existing in the original solvent, there is also the cluster structure solvated with Cu2+, and there is a certain transformation between them. Furthermore, the optimized possible cluster structures and thermodynamic data were calculated by densityfunctional theory. The results confirmed the interaction between Cu2+ and DMF, and the stability of the cluster configurations [Cu(DMF)n]2+(n=1~6) gradually deteriorated with the increase of n. The feasibility and correctness of two-dimensional correlation spectroscopy analysis are verified.
吴晓静，李 志，李子轩，李醒醒，程龙玖. 温度扰动下CuCl2/DMF溶液的二维相关拉曼光谱分析[J]. 光谱学与光谱分析, 2021, 41(01): 177-182.
WU Xiao-jing, LI Zhi, LI Zi-xuan, LI Xing-xing, CHENG Long-jiu. Two-Dimensional Correlation Raman Spectroscopic Analysis of CuCl2/DMF Solution Under Temperature Disturbance. SPECTROSCOPY AND SPECTRAL ANALYSIS, 2021, 41(01): 177-182.
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