【作者】 龙晓燕；

【导师】 应晓；

【作者基本信息】 华南理工大学 ， 材料物理与化学， 2011， 硕士

【摘要】 有机非线性光学（NLO）材料具有易于化学修饰加工、极短的光学响应时间和高的化学损伤阈值等优点在电光调制、光信息存储器、光能转换等领域具有很好的应用前景。这一领域的关键课题之一是如何提高有机生色团的二阶非线性光学性能,而分子具有二阶非线性光学响应的前提是具有非中心对称结构。Corrole是18-π电子共轭大环化合物,环中有一个键由两个吡咯的碳原子直接相连而成,对称性由卟啉的D4h降为C2v。Corrole的本征非中心对称结构为二阶NLO分子设计提供了一个平台。本文在三苯基corrole（TPC）的基础上设计了一系列不同取代位置的氟苯基corrole分子（F5C、F10C和F15C）,不同取代基（-F、-NO₂、-NH₂）形成推拉型corrole系列分子1,2,3,在5,10,15-三（五氟苯基）corrole（TPFC）的基础上分别加入中心金属Cu、Fe和Mn形成金属corrole配合物构建了三大系列模型分子,利用Gaussian 03软件,运用分子模拟方法在6-31G（d,p）水平上用B3LYP方法对所有模型分子进行全面几何构型优化,然后用ZINDO方法计算各分子的电子光谱,再用ZINDO/SOS结合有限场（FF）的方法计算分子的二阶非线性光学系数βHRS,系统地研究了取代位置和取代基团以及金属原子对corrole化合物的二阶非线性光学性质的影响。研究结果表明,三苯基corrole（TPC）分子由于其结构非中心对称使其具有中等大小的一阶超极化率（6.63×10-30esu）。引入氟苯基后,氟苯基corrole系列分子的二阶非线性光学响应明显增强,其中5位及10,15位氟苯基取代的Corrole分子（F5C和F10C）具有较大的一阶超极化率（100×10-30esu）。氟苯基corrole系列分子一阶超极化率提高主要起源于分子的二能级分量及三能级分量显著增大,其中,三能级分量的增加通过改变S5和S6激发态主要跃迁通道,即由TPC分子B带与Q带的耦合变成氟苯基corrole分子B带内两个不同激发态的耦合。电荷密度差图也表明氟苯基引入使得电荷转移沿corrole环向氟苯基方向增强。以具有较大的一阶超极化率的10,15位氟苯基取代的Corrole分子为基础,在非对称方向引入不同取代基（-F、-NO₂、-NH₂）形成推拉型corrole系列分子1,2,3,其一阶超极化率（βHRS（0））的理论计算值以及大小顺序（3>2>1）与实验值吻合得很好。推拉型corrole的一阶超极化率比TPC分子的一阶超极化率提高了一个数量级。引入推基团（-NH₂）的corrole分子3具有最大一阶超极化率,其βHRS（0）的实验值为231?10-30 esu。不同的推拉型corrole之间,取代基不同可以使得分子的一阶超极化率（βHRS（0））有至少40-80%的增加。推拉型corrole系列分子的一阶超极化率的增加主要来源于两个方面:（1）光谱红移及△μng增大引起的二能级贡献的增加;（2）由于两个B带不同激发态耦合增强导致μnń和△ńg增大引起的三能级贡献的增加。电荷密度差图也表明corrole分子沿着非对称方向的电荷转移量与分子的二阶非线性光学系数具有相同趋势。在5,10,15-三（五氟苯基）corrole（TPFC）的基础上分别加入Cu、Fe和Mn原子形成金属corrole配合物系列分子。电子光谱以及二阶非线性光学性质理论分析表明,中心金属原子使得金属corrole分子的光谱Q带振子强度增强,B带振子强度减弱但吸收峰个数增加且整体蓝移。金属corrole系列分子的一阶超极化率的大小顺序为（TPFC）Mn>（TPFC）Cu >（TPFC）Fe。闭壳层体系的（TPFC）Cu分子的一阶超极化率贡献主要来源于B带,且主要来自于两个不同B带的耦合增强引起三能级的贡献增加。开壳层体系的金属corrole配合物中,Q带的作用明显增强,（TPFC）Mn分子一阶超极化率贡献主要来源于Q带的二能级贡献。更多还原

【Abstract】 Organic nonlinear optics （NLO） materials can be modified and processed easily, and they have fast response time and high damage threshold, so NLO materials have important applications in optical communications, information storage, optical switching and signal processing. In this area, one of the most important tasks is to improve the second-order nonlinear optical properties of organic chromophores, and the non-vanishing requirement of the second-order nonlinear optical response is non-centrosymmetry. Corroles are 18-πelectron conjugate macrocycles bearing a direct pyrrole-pyrrole link, their symmetry are C2v dropped from D4h of porphyrins. The intrinsic non-centrosymmetric structure of corrole may render it a new chromophore of second order NLO materials.In this paper, we designed a series of pentafluorophenyl substituted corroles （F5C, F10C and F15C） in different positions and a series of donor-accepter corroles（1, 2 and3） with different substituents （-F, -NO₂, -NH₂） on the base of the tri-phenylcorrole （TPC）. On the base of 5,10,15-three（five pentafluorophenyl） corrole（TPFC）, we also designed a series of metal corrole complexes with the central atom Cu, Fe and Mn. Quantum chemical software Gaussian 03 was employed in calculation, and the geometries of all the molecules are fully optimized by the 6-31G（d,p）/B3LYP method, then the electronic spectras were calculated by the method of ZINDO. At last, the first hyperpolarizabilities （βHRS） were calculated via the ZINDO/SOS combined with the Finite Field （FF） method. We systematically studied the second-order nonlinear optical properties of corroles influenced by the position of substituents, the types of donor-accepters and the metal atoms.Results showed that the first hyperpolarizabilitie of TPC was of moderate value （66.7×10-30esu） due to its non-symmetrical geometry structure. The first hyperpolarizabilities of pentafluorophenyl substituted corroles increased significantly due to the pentafluorophenyl. The 10,15-phenyl-5-（pentafluorophenyl）corrole and 5-phenyl-10,15-di（pentafluorophenyl） corrole （F5C and F10C） showed the largest first hyperpolarizabilities （100×10-30esu）. The enhancement of first hyperpolarizabilities of pentafluorophenyl substituted corrole originated from the dramatically increasing of their three-level components and three-level components. The three-level components was caused by changing the pivotal transition channel of exited states from coupling between B and Q bands in TPC to the coupling between two different exited states of B band in the pentafluorophenyl substituted corrole. The electron density difference maps also showed that the charge transfer along corrole ring and pentafluorophenyl is enhanced due to the pentafluorophenyl substituted.The experimental and theoretical results on the trend （3>2>1） of the first hyperpolarizability of donor-acceptor corroles are in good accordance. TheβHRS（0） values of donor-acceptor corroles are an order larger than that of TPC without substituents. Due to the donor （-NH₂） substituent, corrole 3 has the largestβHRS（0） values （231?10-30 esu）. Within the donor-acceptor corroles, variation of substituents can enhance the first hyperpolarizability,βHRS（0）, by at least 40-80% of magnitude. Our calculations indicate that the increment of first hyperpolarizability in donor-acceptor corrole is due to two factors: （1） the increasing two-level component, mainly from B1 state originated from red shift and increasing△μng and （2）the enhanced three-level component, resulting in the increasing ofμnńand ?ńg due to strengthened coupling between two different excited states of B band. The electron density difference maps also showed that the charge transfers along nonsymmetrical axis are accordance with the trend of the second-order nonlinear properties.The electron spectra and the theoretical analysis of the second-order nonlinear optical properties showed that, for the metal corroles systems, the oscillator strength of Q bands are enhanced. However, the oscillator strength of B bands is weakened and the whole B bands are blue shifted. The order of the first hyperpolarizability of metal corroles is （TPFC）Mn>（TPFC）Cu >（TPFC）Fe. For the close shell system, the first hyperpolarizability of （TPFC）Cu is originated from B band, and it is from its three-level components due to the strong coupling between two different excited states of B band. For the open shell systems of metal corroles, the contributions of Q band are enhanced, and the first hyperpolarizability of （TPFC）Mn is originate from Q band.更多还原