本文選題：太赫茲光譜　切入點(diǎn)：結(jié)晶水　出處：《華東理工大學(xué)》2017年碩士論文

【摘要】：太赫茲(THz)光譜對(duì)水合物的分子結(jié)構(gòu)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(jié)構(gòu)特點(diǎn),進(jìn)而為理解分子結(jié)構(gòu)與功能關(guān)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(duì)象,發(fā)現(xiàn)無(wú)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(duì)無(wú)水物和水合物進(jìn)行定性分析。結(jié)合SEM的表征結(jié)果,證明了水分子可以誘導(dǎo)分子自組裝形成超分子結(jié)構(gòu),使無(wú)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(duì)象,實(shí)現(xiàn)了用THz光譜對(duì)水合物的脫水過(guò)程進(jìn)行實(shí)時(shí)監(jiān)測(cè)。實(shí)驗(yàn)中驗(yàn)證了 THz光譜與溫度效應(yīng)之間的關(guān)系,并以氣態(tài)水分子為探針,首次提出了吹掃氣(氮?dú)�、干燥空�?在THz光譜表征水合物脫水過(guò)程中的重要性。結(jié)合量子化學(xué)計(jì)算,用密度泛函理論對(duì)晶胞進(jìn)行結(jié)構(gòu)優(yōu)化和能量?jī)?yōu)化計(jì)算,從分子層面去解析THz光譜信息。根據(jù)計(jì)算結(jié)果將THz光譜的特征吸收峰歸屬到了具體的振動(dòng)模式,THz吸收峰起源于分子間的振動(dòng)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(luò),對(duì)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(jié)構(gòu)與誘變劑之間的作用機(jī)理,以DNA結(jié)構(gòu)中的堿基胞嘧啶和誘變劑草酸為研究對(duì)象,發(fā)現(xiàn)了在結(jié)晶水的參與下,胞嘧啶和草酸會(huì)通過(guò)分子識(shí)別作用生成共晶物,共晶物在THz波段具有特征吸收峰。進(jìn)一步用THz光譜追蹤分子識(shí)別反應(yīng)過(guò)程,發(fā)現(xiàn)了胞嘧啶和草酸中的結(jié)晶水在分子識(shí)別過(guò)程中具有不同的作用。利用密度泛函理論,對(duì)共晶物晶胞進(jìn)行結(jié)構(gòu)優(yōu)化和能量?jī)?yōu)化計(jì)算。根據(jù)計(jì)算結(jié)果,將共晶物的特征吸收峰歸屬到了具體的振動(dòng)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(gè)角度,闡釋了結(jié)晶水在分子識(shí)別過(guò)程中的作用機(jī)理,得到了胞嘧啶和草酸發(fā)生分子識(shí)別反應(yīng)的條件,該研究成果對(duì)草酸誘導(dǎo)DNA結(jié)構(gòu)變性的機(jī)理有一定的指導(dǎo)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(xué)位授予單位】：華東理工大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2017
【分類(lèi)號(hào)】：O641.3

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