激发态链式质子转移及分子内质子转移的理论研究

发布时间：2018-06-26 08:11

本文选题：氢键 + 激发态质子转移(ESPT)　；参考：《辽宁大学》2016年硕士论文

【摘要】：激发态质子转移(ESPT)是极为重要且十分常见的反应,通常伴随着其它物理化学常见反应的发生而进行。自然界中多数物质都有氢键的形成,它能使物质的性质发生一定变化。氢键是最早被研究的弱相互作用之一,分子在光激发作用下到达激发态,氢键作用会使分子中的某一质子或氢原子通过氢键发生转移。其中,由于氢键作用而发生的激发态质子转移应用范围较广,例如：荧光探针的设计与应用,激光染料和发光二极管,紫外线吸收剂和分子开关等等。激发态质子转移的研究对于研究新型发光材料、研发新药物及探索生命体征都发挥着十分重要的作用。本文主要对7AI-2H_2O体系和BBPC体系在激发态发生的的质子转移机制进行了深入的研究和详细的探讨。两个体系的所有计算都是在高斯09软件下展开的,主要采用的方法是密度泛函(DFT)理论和含时密度泛函(TDDFT)理论。我们通过对7AI-2H_2O体系理论计算结果及扫取的势能曲线进行分析,发现7AI-2H_2O体系沿着氢键链进行激发态链式多质子转移反应,这个过程是比较特别的。另外,我们发现前人均仅采用节面模型方法来研究激发态质子转移的机理,虽然节面模型提出了势垒阻碍的问题,但并不能给出势垒大小情况,其结论的可靠性是值得我们怀疑的。借助我们构建的势能面,对BBPC体系激发态上的分子内单质子转移与双质子转移相互竞争机制进行探讨,根据对计算结果的分析,我们提出BBPC体系在激发态能够产生两个等价的单质子转移反应。这些研究成果不仅说明了量化计算方法的合理性与高效性,更进一步提出了通过构建大分子势能面的方法解释激发态质子转移机理。
[Abstract]:Excited state proton transfer (ESPT) is a very important and common reaction, which is usually accompanied by other physical and chemical reactions. Most substances in nature have hydrogen bonds, which can change the nature of matter. Hydrogen bond is one of the first weak interactions studied. The molecule reaches the excited state under the action of light. The hydrogen bond will make a proton or hydrogen atom in the molecule transfer through the hydrogen bond. Among them, the excited proton transfer due to hydrogen bonding has a wide range of applications, such as the design and application of fluorescent probes, laser dyes and light-emitting diodes, ultraviolet absorbers and molecular switches, and so on. The study of excited proton transfer plays an important role in studying new luminescent materials, developing new drugs and exploring vital signs. In this paper, the proton transfer mechanism in excited states of 7AI-2H2O and BBPC systems is studied and discussed in detail. All the calculations of the two systems are carried out under the software of Gao Si 09. The main methods are density functional theory and time-dependent density functional theory. By analyzing the theoretical calculation results of 7AI-2H2O system and the potential energy curve, we find that 7AI-2H2O system performs excited chain multi-proton transfer reaction along the hydrogen bond chain, which is a special process. In addition, we find that the nodal model method is only used to study the mechanism of excited proton transfer. Although the nodal model raises the problem of barrier hindrance, it can not give the size of potential barrier. The reliability of the conclusion is doubtful. With the help of the potential energy surface constructed by us, the competitive mechanism of intramolecular single proton transfer and double proton transfer on the excited state of BBPC system is discussed. We propose that the BBPC system can produce two equivalent single proton transfer reactions in the excited state. These results not only explain the rationality and efficiency of the quantitative calculation method, but also explain the mechanism of excited proton transfer by constructing the potential energy surface of large molecules.
【学位授予单位】：辽宁大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：O641

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