硫代巴比妥酸多晶型的太赫兹光谱和DFT理论分析  

Terahertz Spectroscopy and Density Functional Theory Investigation of 2-Thiobarbituric Acid Polymorphs

作　　者：张琪[1] 方虹霞 张慧丽[1] 秦丹[1] 洪治[1] 杜勇[1] 

机构地区：[1]中国计量大学太赫兹技术与应用研究所,浙江杭州310018

出　　处：《光谱学与光谱分析》2017年第12期3677-3682,共6页Spectroscopy and Spectral Analysis

基　　金：国家自然科学基金项目(21205110);浙江省自然科学基金项目(LY15B050004)资助

摘　　要：硫代巴比妥酸是目前多晶型种类较丰富的一类固体药物。利用太赫兹时域光谱(THz-TDS)技术对硫代巴比妥酸晶型Ⅰ,Ⅱ,Ⅲ,Ⅳ和水合晶型进行表征分析,得到明显不同的太赫兹光谱,表明THz光谱技术可以有效鉴别硫代巴比妥酸不同类多晶型。硫代巴比妥酸晶型Ⅳ为异构多晶型,它在0.65THz处的宽峰以及1.02,1.41THz处的吸收峰明显区别于晶型Ⅰ和Ⅱ简单的物理混合。运用密度泛函理论(DFT)对硫代巴比妥酸晶型Ⅳ的两种可能结构进行了分子结构优化和光谱模拟,模拟结果显示其中的结构a在0.41/0.47,0.89和1.35THz处具有吸收峰,与实验结果较吻合。由此推断晶型Ⅳ由硫代巴比妥酸异构体A的硫酮键中的S7和异构体B酰胺中的H_23构成第一处氢键,异构体B硫酮键中的S20和异构体A酰胺中的H13形成第二处氢键。本文还结合理论模拟结果对硫代巴比妥酸晶型Ⅳ的振动模式进行归属。2-Thiobarbituric acid （TBA） is one of the most polymorphic rich molecular solids currently known .Here ,five most common polymorphs of TBA （form Ⅰ ,Ⅱ ,Ⅲ ,Ⅳ and hydrate） were investigated using terahertz time-domain spectroscopy （THz-TDS） .All results of the terahertz spectra showed that there were significantly different absorption features for poly-morphs ,which indicated that THz-TDS technique could effectively identify different types of TBA polymorphs .Form Ⅳ belongs to the tautomeric polymorph ,and the absorption features of form Ⅳ at 0.65（broad band） ,1.02 and 1.41 THz are significantly different from physical mixture of form Ⅰ and form Ⅱ .Density functional theory （DFT） calculation was performed to optimize two possible molecular structures and simulate the corresponding vibrational spectra .The theoretical result showed that simula-ted structure （form a） had absorption peaks at 0.41/0.47 ,0.89 and 1.35 THz ,which agrees with the THz experimental spec-trum .Therefore ,it is confirmed that ,in the TBA form Ⅳ ,the first hydrogen bond is formed between thione S7 of isomer A and amide H23 of isomer B in the structure of form Ⅳ ,while the second one is constituted by amide H13 of isomer A and thione S20 of isomer B .The characteristic absorption modes of form Ⅳare also assigned based on the simulation results of DFT calculation .

关 键 词：硫代巴比妥酸 多晶型 氢键 太赫兹时域光谱 密度泛函理论 

分 类 号：O657.3[理学—分析化学]