本文選題：氫鍵 + 激發(fā)態(tài)質(zhì)子轉(zhuǎn)移�。� 參考：《湖南科技大學(xué)》2017年碩士論文

【摘要】：質(zhì)子轉(zhuǎn)移廣泛存在于自然界中,是化學(xué)和生物領(lǐng)域中的重要反應(yīng)。激發(fā)態(tài)質(zhì)子轉(zhuǎn)移在物理和生物系統(tǒng)中扮演著十分重要的角色,近年來越來越多的研究者從實(shí)驗(yàn)和理論方面來探究激發(fā)態(tài)分子質(zhì)子轉(zhuǎn)移的性質(zhì)。本論文采用量子化學(xué)計(jì)算方法探討了[2,2-聯(lián)吡啶]-3,3-二醇(Bp(OH)2)、10-羥基苯并喹啉(HBQ)等含氮雜環(huán)化合物激發(fā)態(tài)分子內(nèi)質(zhì)子轉(zhuǎn)移機(jī)理及其性質(zhì),為此類分子的設(shè)計(jì)提供了一定的理論基礎(chǔ)。同時(shí),結(jié)合光譜實(shí)驗(yàn),考察了溶劑、溫度以及在瓜環(huán)的超分子作用下對HBQ質(zhì)子轉(zhuǎn)移的影響。1.采用密度泛函(DFT)和含時(shí)密度泛函(TD-DFT)計(jì)算方法研究了Bp(OH)2的激發(fā)態(tài)分子內(nèi)雙質(zhì)子轉(zhuǎn)移(ESIDPT)性質(zhì)。通過對鍵長、鍵角、紅外振動(dòng)光譜以及氫鍵鍵能的分析,發(fā)現(xiàn)Bp(OH)2分子從基態(tài)光致激發(fā)到達(dá)第一激發(fā)態(tài)后,分子內(nèi)雙氫鍵顯著加強(qiáng),而分子內(nèi)氫鍵的加強(qiáng)促進(jìn)了激發(fā)態(tài)質(zhì)子轉(zhuǎn)移。質(zhì)子轉(zhuǎn)移的勢能面表明,在基態(tài)和激發(fā)態(tài)時(shí)均能發(fā)生單質(zhì)子和雙質(zhì)子轉(zhuǎn)移,且激發(fā)態(tài)的雙質(zhì)子轉(zhuǎn)移是分步進(jìn)行的,在實(shí)驗(yàn)中出現(xiàn)的斯托克位移變化可以根據(jù)ESIDPT機(jī)理得到較好的解釋。2.運(yùn)用密度泛函(DFT)和含時(shí)密度泛函(TD-DFT)計(jì)算方法研究了HBQ及其衍生物分子內(nèi)質(zhì)子轉(zhuǎn)移過程,考察了取代基效應(yīng)對質(zhì)子轉(zhuǎn)移過程的影響。研究發(fā)現(xiàn),HBQ及其衍生物可以形成分子內(nèi)氫鍵,且激發(fā)態(tài)時(shí)氫鍵增強(qiáng)�；鶓B(tài)時(shí)各分子以醇式構(gòu)型穩(wěn)定存在,激發(fā)態(tài)時(shí)酮式構(gòu)型為優(yōu)勢構(gòu)象。各化合物的最大吸收峰主要是電子從HOMO到LUMO之間的躍遷引起的�；鶓B(tài)分子內(nèi)質(zhì)子轉(zhuǎn)移(醇式→酮式)需要躍過較高的能壘因而難以發(fā)生,而激發(fā)態(tài)時(shí)只需躍過較低能壘就很容易發(fā)生分子內(nèi)質(zhì)子轉(zhuǎn)移,吸電子基的引入可以使該過程的能壘降低,因此吸電子基有利于激發(fā)態(tài)質(zhì)子轉(zhuǎn)移。取代基效應(yīng)影響化合物的光譜性質(zhì)。3.采用熒光光譜法并結(jié)合量子化學(xué)理論計(jì)算,研究了溶劑、溫度以及七元瓜環(huán)的超分子作用對HBQ質(zhì)子轉(zhuǎn)移的影響。結(jié)果表明,極性溶劑在一定程度上促進(jìn)了HBQ激發(fā)態(tài)質(zhì)子轉(zhuǎn)移。瞬態(tài)熒光的研究可知,隨著七元瓜環(huán)的加入其量子產(chǎn)率增加。根據(jù)與七元瓜環(huán)相互作用的熒光光譜及理論計(jì)算結(jié)果表明HBQ與七元瓜環(huán)形成了1:1的包合物。運(yùn)用量子化學(xué)理論方法考察了溶劑對HBQ質(zhì)子轉(zhuǎn)移過程中勢能曲線的影響,根據(jù)模擬出的勢能曲線可以推測出極性溶劑促進(jìn)了分子內(nèi)激發(fā)態(tài)質(zhì)子轉(zhuǎn)移,從而促使醇式到酮式的轉(zhuǎn)變,使長波處熒光增強(qiáng),這與實(shí)驗(yàn)數(shù)據(jù)得出的結(jié)論一致。
[Abstract]:Proton transfer exists widely in nature and is an important reaction in chemical and biological fields. Excited proton transfer plays a very important role in physical and biological systems. In recent years, more and more researchers have explored the properties of excited state proton transfer from experimental and theoretical aspects. In this paper, the quantum chemical method is used to study the mechanism and properties of the excited states of [2 (2) -bipyridine] -3- (3) -diol (BpOHN) (10-hydroxybenzo-quinoline (HBQ), which provide a theoretical basis for the design of this kind of molecules. At the same time, the effects of solvent, temperature and supramolecular action of melon ring on the proton transfer of HBQ were investigated. The properties of excited intramolecular double proton transfer (Bp(OH)2) in Bp(OH)2 have been studied by density functional theory (DFT) and time-dependent density functional spectroscopy (TD-DFT). Based on the analysis of bond length, bond angle, infrared vibrational spectrum and hydrogen bond energy, it is found that the intramolecular double hydrogen bond is significantly strengthened when the Bp(OH)2 molecule is excited from the ground state to the first excited state, and the enhancement of the intramolecular hydrogen bond promotes the proton transfer in the excited state. The potential energy surface of the proton transfer shows that both the elementary and the double proton transfer can occur in the ground state and the excited state, and the double proton transfer of the excited state is carried out step by step. The Stoke displacement can be explained according to the ESIDPT mechanism. The intramolecular proton transfer processes of HBQ and its derivatives were studied by using density functional theory (DFT) and time-dependent density functional theory (TD-DFT). The effect of substituent effect on the proton transfer process was investigated. It is found that HBQ and its derivatives can form intramolecular hydrogen bonds, and the hydrogen bonds are enhanced in excited states. In the ground state, the alcohol-type configuration is stable, and the ketone configuration is the dominant conformation in the excited state. The maximum absorption peaks of the compounds are mainly caused by the transition of electrons from HOMO to LUMO. The intramolecular proton transfer in the ground state (alcohol-ketone type) is difficult to occur due to the need to leap over the higher barrier, while the intramolecular proton transfer is easy to occur in the excited state by simply jumping over the lower barrier. The energy barrier of the process can be reduced by the introduction of the electron-absorbing group, so the electron-absorbing group is advantageous to the proton transfer in the excited state. The substituent effect affects the spectral properties of the compounds. The effects of solvent, temperature and supramolecular interaction of seven-member melon ring on HBQ proton transfer were studied by fluorescence spectroscopy and quantum chemical theory. The results show that polar solvents can promote the proton transfer of HBQ excited state to some extent. The study of transient fluorescence shows that the quantum yield increases with the addition of seven-member melon ring. According to the fluorescence spectra and theoretical calculations of the interaction between HBQ and the seven-member melon ring, the inclusion complex of 1:1 was formed between the HBQ and the seven-member melon ring. The influence of solvent on the potential energy curve of HBQ proton transfer was investigated by using quantum chemical theory. According to the simulated potential energy curve, it can be inferred that polar solvents promote intramolecular excited proton transfer. Thus, the conversion of alcohol form to ketone form is promoted, and the fluorescence at long wave is enhanced, which is consistent with the conclusion of experimental data.
【學(xué)位授予單位】：湖南科技大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2017
【分類號】：O626

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