邻位含氟偶氮苯光控开关分子内电荷转移的理论研究

发布时间：2018-01-12 20:18

本文关键词：邻位含氟偶氮苯光控开关分子内电荷转移的理论研究　出处：《辽宁大学》2014年硕士论文　论文类型：学位论文

【摘要】：置身信息时代的浪潮中，海量的信息存储使人们对光信息存储材料的需求十分迫切。偶氮苯—新型光致变色化合物中的一种，以其卓越的光学特性—光致变色顺反异构性，在生物材料、光信息材料等众多领域炙手可热，成为光信息存储材料中的宠儿。然而偶氮苯自身却存在两大不容忽视的缺点。首先是利用紫外光，必须通过*激发来诱导反→顺异构化，但却潜在地影响和破坏了周围的环境；其次是不完全可逆的顺→反光异构化，这种异构化需要可见光辐射来诱导，但此时顺、反异构物的n*吸收带常被忽略，因此在分子翻转后不能表现出E（反）异构物丰富的光稳定性。我们可以通过调整偶氮苯分子的化学结构，消除上述弊端，改善其物理化学性质。在本论文中，我们将利用2,6-二氟苯胺合成邻位四基含氟偶氮苯，通过在邻位含氟偶氮苯的对位引入氨酰基这类给电子性的基团（EDGS）和酯基这类拉电子性的基团（EWGS），来调节光谱特征，扩大吸收量和n*吸收带的间隔。分子1以N-acyl基团作为电子给体（donor）,o-fluoroazobenzenes基团作为电子受体（acceptor）；对于分子2，o-fluoroazobenzenes成为电子给体，电子受体是拉电子性的ester基团。本文中，我们主要采用量子化学方法进行理论研究。运用密度泛函理论（Density Functional Theory，DFT）中的B3LYP函数和DZVP基组对分子1和分子2的顺反异构物进行几何结构优化，并对其基态、激发态性质进行理论研究和计算，同时列出分子相对最高占据分子轨道（the highest occupied molecular orbital, HOMO）和最低未占据分子轨道（the lowest unoccupied molecular orbital, LUMO）以及相对应的能量。分子1的反、顺异构物的主要峰值是403.18nm和329.84nm，分别是HOMO→LUMO和HOMO-1→LUMO轨道电子跃迁的结果；分子2的反、顺异构物的主要峰值为371.65nm和468.66nm，分别是两轨道HOMO-1→LUMO和HOMO-4→LUMO。为了深入研究分子1和分子2的激发态性质，，我们在本论文中做出了分子1和分子2的UV吸收光谱和圆二色光谱。对于分子内电荷转移情况，我们利用三维实空间分析方法，将分子1、分子2的电荷转移过程可视化。跃迁密度（TD）揭示偶极矩跃迁转变方向和强度，电荷差异密度（CDD）显示了分子内电荷跃迁的方向和结果,DOS揭示了原子态密度在HOMO和LUMO轨道上的分布情况。利用2维（2D）实空间分析方法来分析电子-空穴的相干性和电子离域，进而比较三维实空间分析结果与二维实空间分析结果的一致性。
[Abstract]:In the tide of information age, mass information storage makes the demand of optical information storage material very urgent. Azobenzene is one of the new photochromic compounds. Because of its excellent optical properties, photochromic discoloration and anti-isomerism are popular in many fields, such as biomaterials, optical information materials and so on, and become the favorite of optical information storage materials. However, azobenzene itself has two shortcomings that can not be ignored. First, the use of ultraviolet light must be induced by excitation. 鈫扖is-isomerization, but potentially affecting and destroying the surrounding environment; followed by incomplete reversible cis-isomerization. 鈫扲eflective isomerization, which requires visible light radiation to induce the isomerization, but the N * absorption bands of the cis-trans isomers are often ignored. Therefore, the photostability of E- (inverse) isomers can not be shown after the molecular inversion. We can eliminate the above disadvantages by adjusting the chemical structure of azobenzene molecules and improve their physical and chemical properties. In this thesis, we will synthesize o-tetrafluoroazobenzene from 2-fluoro-6-difluoroaniline. The spectral characteristics were regulated by the introduction of electron-giving groups such as aminoyl groups (EDGSs) and electron-pulling groups such as ester groups (EWGSN) into the p-fluoroazobenzene containing o-fluoroazobenzene. The distance between the absorption band and the absorption band of n * is enlarged. Molecule 1 is composed of N-acyl group as the electron donor). The o-fluoroazobenzenes group was used as the electron acceptor. For the molecular 2- fluorofluoroazobenzenes as an electron donor, the electron acceptor is an electron-pulling ester group. We mainly use the quantum chemical method to study the theory and the density functional theory (Density Functional Theory). B3LYP function and DZVP basis set are used to optimize the geometric structure of the cis-trans isomers of molecule 1 and molecular 2, and the properties of ground state and excited state are studied and calculated theoretically. At the same time, the relative highest occupied molecular orbital of the highest occupied molecular orbital is listed. Homo) and the lowest unoccupied molecular orbital, the lowest unoccupied molecular orbital. Lumo) and the corresponding energy. The main peak values of cis-isomers of molecule 1 are 403.18 nm and 329.84 nm, respectively, which are HOMO. 鈫扡UMO and HOMO-1. 鈫扵he results of electron transition of LUMO orbitals; the main peaks of molecular 2 are 371.65 nm and 468.66 nm, respectively, which are two-orbital HOMO-1. 鈫扡UMO and HOMO-4. 鈫扞n order to study the excited state properties of molecule 1 and molecular 2, we have made UV absorption spectra and circular dichroism spectra of molecule 1 and molecular 2 in this thesis. Using three-dimensional real space analysis method, we visualize the charge transfer process of molecule 1 and molecule 2. The transition density (TD) reveals the transition direction and intensity of dipole moment transition. The charge difference density (CDD) shows the direction and result of intramolecular charge transition. DOS reveals the distribution of atomic density of states on HOMO and LUMO orbitals. The coherence and delocalization of electron holes are analyzed by using the real space analysis method. Then the consistency between the results of 3D real space analysis and two dimensional real space analysis is compared.
【学位授予单位】：辽宁大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TP333;O561

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