本文選題：太赫茲光譜　切入點：結晶水　出處：《華東理工大學》2017年碩士論文

【摘要】：太赫茲(THz)光譜對水合物的分子結構和分子間的弱相互作用力很敏感,解析水合物分子在THz波段的光譜信息,可以從新的角度去研究分子的結構特點,進而為理解分子結構與功能關系提供新的依據(jù)。以茚三酮及其水合物、胞嘧啶及其水合物為研究對象,發(fā)現(xiàn)無水物和水合物在THz波段有特征吸收峰,用THz光譜可以快速有效的對無水物和水合物進行定性分析。結合SEM的表征結果,證明了水分子可以誘導分子自組裝形成超分子結構,使無水物和水合物具有完全不同的表面形貌。以茚三酮水合物為研究對象,實現(xiàn)了用THz光譜對水合物的脫水過程進行實時監(jiān)測。實驗中驗證了 THz光譜與溫度效應之間的關系,并以氣態(tài)水分子為探針,首次提出了吹掃氣(氮氣、干燥空氣)在THz光譜表征水合物脫水過程中的重要性。結合量子化學計算,用密度泛函理論對晶胞進行結構優(yōu)化和能量優(yōu)化計算,從分子層面去解析THz光譜信息。根據(jù)計算結果將THz光譜的特征吸收峰歸屬到了具體的振動模式,THz吸收峰起源于分子間的振動模式和分子間相互作用力。其中,水分子在晶胞中形成的氫鍵網(wǎng)絡,對晶格的穩(wěn)定發(fā)揮著重要的作用。為了研究生物分子中DNA結構與誘變劑之間的作用機理,以DNA結構中的堿基胞嘧啶和誘變劑草酸為研究對象,發(fā)現(xiàn)了在結晶水的參與下,胞嘧啶和草酸會通過分子識別作用生成共晶物,共晶物在THz波段具有特征吸收峰。進一步用THz光譜追蹤分子識別反應過程,發(fā)現(xiàn)了胞嘧啶和草酸中的結晶水在分子識別過程中具有不同的作用。利用密度泛函理論,對共晶物晶胞進行結構優(yōu)化和能量優(yōu)化計算。根據(jù)計算結果,將共晶物的特征吸收峰歸屬到了具體的振動模式,并從晶體內(nèi)能、晶胞內(nèi)分子排列和分子間的相互作用力三個角度,闡釋了結晶水在分子識別過程中的作用機理,得到了胞嘧啶和草酸發(fā)生分子識別反應的條件,該研究成果對草酸誘導DNA結構變性的機理有一定的指導意義。
[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.
【學位授予單位】：華東理工大學
【學位級別】：碩士
【學位授予年份】：2017
【分類號】：O641.3

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