太赫兹光谱与密度泛函理论研究胸腺嘧啶与尿素共晶体结构  

Co-crystal between thymine and urea investigated with Terahertz spectroscopy and density functional theory

作　　者：马蔷 王玉贤[1] 张卓勇[1] 王果[1] 相玉红[1] 

机构地区：[1]首都师范大学化学系,北京100048

出　　处：《兰州大学学报（自然科学版）》2017年第6期841-846,共6页Journal of Lanzhou University(Natural Sciences)

基　　金：国家自然科学基金项目(2127510)

摘　　要：利用太赫兹时域光谱技术对胸腺嘧啶、尿素及其水溶液旋蒸产物与固态研磨产物进行表征分析.结果表明,胸腺嘧啶和尿素在两种环境下作用后的产物均在0.75、0.94 THz处出现明显区别于原料物质的吸收峰.采用密度泛函理论对胸腺嘧啶和尿素共晶体的5种可能结构模型进行了优化和光谱模拟,结果显示其中的共晶体结构E在0.76、0.98 THz处存在特征吸收峰,与实验吸收峰位置基本吻合.由此判断,胸腺嘧啶与尿素在水溶液与固态研磨条件下均可以通过氢键形成物相结构一致的共晶体.该结果表明太赫兹光谱技术可以有效地鉴别和分析胸腺嘧啶、尿素及其共晶体.结合理论模拟结果对胸腺嘧啶与尿素的共晶体吸收峰对应的相关振动模式进行了归属.Terahertz time-domain spectroscopy technology was utilized for the characterization and analysis of thymine, urea and their co-crystal products yielded from cogrinding and solution. Experimental results showed that similar absorption peaks of co-crystal products from cogrinding and solution, which were formed by thymine and urea at 0.75, 0.94 THz, could be observed, indicating that they were the same materials. The position and intensity of absorption peaks for such products were significantly different from their corresponding original materials. The optimized geometries and vibrational spectra of five feasible theoretical molecular structures of the thymine-urea co-crystal were performed with the density functional theory （DFT） calculation, and the theoretical results showed that absorption peaks at 0.76, 0.98 THz occurred in structure E, which was much in agreement with the THz experimental result. A comparison of the experimental and theoretical results confirmed that a co-crystal configuration linked by a pair of hydrogen bonds between thymine and urea was formed. This work can provide experimental and theoretical benchmarks to the detection and analysis of hydrogen bonding interaction and molecular structure of thymine-urea co-crystal with the newly developed terahertz spectroscopic technology. The vibrational modes of the thymine-urea co-crystal were also assigned with the help of the simulated DFT results.

关 键 词：太赫兹时域光谱 胸腺嘧啶 尿素 共晶体 氢键 

分 类 号：O641[理学—物理化学] O657.3[理学—化学]