太赫兹光谱在水合物和固态分子识别反应中的应用研究

发布时间：2018-04-04 19:20

本文选题：太赫兹光谱　切入点：结晶水　出处：《华东理工大学》2017年硕士论文

【摘要】：太赫兹(THz)光谱对水合物的分子结构和分子间的弱相互作用力很敏感,解析水合物分子在THz波段的光谱信息,可以从新的角度去研究分子的结构特点,进而为理解分子结构与功能关系提供新的依据。以茚三酮及其水合物、胞嘧啶及其水合物为研究对象,发现无水物和水合物在THz波段有特征吸收峰,用THz光谱可以快速有效的对无水物和水合物进行定性分析。结合SEM的表征结果,证明了水分子可以诱导分子自组装形成超分子结构,使无水物和水合物具有完全不同的表面形貌。以茚三酮水合物为研究对象,实现了用THz光谱对水合物的脱水过程进行实时监测。实验中验证了 THz光谱与温度效应之间的关系,并以气态水分子为探针,首次提出了吹扫气(氮气、干燥空气)在THz光谱表征水合物脱水过程中的重要性。结合量子化学计算,用密度泛函理论对晶胞进行结构优化和能量优化计算,从分子层面去解析THz光谱信息。根据计算结果将THz光谱的特征吸收峰归属到了具体的振动模式,THz吸收峰起源于分子间的振动模式和分子间相互作用力。其中,水分子在晶胞中形成的氢键网络,对晶格的稳定发挥着重要的作用。为了研究生物分子中DNA结构与诱变剂之间的作用机理,以DNA结构中的碱基胞嘧啶和诱变剂草酸为研究对象,发现了在结晶水的参与下,胞嘧啶和草酸会通过分子识别作用生成共晶物,共晶物在THz波段具有特征吸收峰。进一步用THz光谱追踪分子识别反应过程,发现了胞嘧啶和草酸中的结晶水在分子识别过程中具有不同的作用。利用密度泛函理论,对共晶物晶胞进行结构优化和能量优化计算。根据计算结果,将共晶物的特征吸收峰归属到了具体的振动模式,并从晶体内能、晶胞内分子排列和分子间的相互作用力三个角度,阐释了结晶水在分子识别过程中的作用机理,得到了胞嘧啶和草酸发生分子识别反应的条件,该研究成果对草酸诱导DNA结构变性的机理有一定的指导意义。
[Abstract]:The THz spectrum is very sensitive to the molecular structure of hydrate and the weak interaction between molecules. To analyze the spectral information of hydrate molecules in the THz band, we can study the structural characteristics of the molecules from a new perspective.It provides a new basis for understanding the relationship between molecular structure and function.Taking ninhydrin and its hydrates, cytosine and their hydrates as the research object, we found that anhydrous compounds and hydrates have characteristic absorption peaks in the THz band. The anhydrous compounds and hydrates can be analyzed qualitatively and efficiently by THz spectra.Combined with the results of SEM, it is proved that water molecules can induce the self-assembly of molecules to form supramolecular structures and make anhydrous compounds and hydrates have completely different surface morphology.The dehydration process of ninhydrin hydrate was monitored by THz spectroscopy.The relationship between THz spectrum and temperature effect was verified in the experiment. The importance of purging gas (nitrogen, dry air) in the process of dehydration of hydrate by THz spectroscopy was first put forward with the gaseous water molecule as the probe.Based on the quantum chemical calculation, the structure and energy of the crystal cell were optimized by density functional theory, and the THz spectral information was analyzed from the molecular level.According to the calculated results, the characteristic absorption peaks of the THz spectrum are assigned to the specific vibrational mode. The THz absorption peak originates from the vibrational mode between molecules and the interaction between molecules.The hydrogen bond network formed by water molecules in the crystal cell plays an important role in the stability of lattice.In order to study the interaction mechanism between DNA structure and mutagen in biomolecules, base cytosine and oxalic acid in DNA structure were studied.Cytosine and oxalic acid can form eutectic compounds by molecular recognition. The eutectic compounds have characteristic absorption peaks in THz band.The THz spectra were used to trace the molecular recognition reaction process and it was found that the crystalline water in cytosine and oxalic acid had different roles in the molecular recognition process.Based on density functional theory, the structure and energy of eutectic cell were optimized.According to the calculated results, the characteristic absorption peaks of eutectic compounds are assigned to specific vibrational modes, and from the three angles of crystal energy, cell molecular arrangement and intermolecular interaction forces,The action mechanism of crystalline water in molecular recognition process was explained, and the conditions of molecular recognition reaction between cytosine and oxalic acid were obtained. The results of this study have a certain guiding significance on the mechanism of oxalic acid-induced structural denaturation of DNA.
【学位授予单位】：华东理工大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：O641.3

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