温度扰动下CuCl<sub>2</sub>/DMF溶液的二维相关拉曼光谱分析

doi:10.3964/j.issn.1000-0593(2021)01-0177-06

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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.

Key words：Density functional theory; Two-dimensional Raman spectroscopy; Moving-window two-dimensional Raman spectroscopy; Solvation

Received: 2019-11-26 Accepted: 2020-04-02

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https://www.gpxygpfx.com/EN/10.3964/j.issn.1000-0593(2021)01-0177-06 OR https://www.gpxygpfx.com/EN/Y2021/V41/I01/177