【作者】 麻娜娜；

【导师】 仇永清； 苏忠民；

【作者基本信息】 东北师范大学 ， 物理化学， 2014， 博士

【摘要】 多面体硼簇化合物是一类通过共价键构成的具有特殊结构和非常规成键的化合物，因其丰富的形成种类、特殊的电子结构以及良好的化学稳定性，而具有很多的潜在应用，例如金属离子萃取、医药、催化、离子选择电极以及工业生产等。另外，由于其高的热稳定性，并在紫外光区有很好的透明性，以及其高度离域和大量的可极化电子，使得这类簇合物能够满足非线性光学(NLO)材料的很多要求。多面体硼烷、杂硼烷以及金属杂硼烷的二阶NLO性质已经受到了人们的关注，并进行了实验和理论上的研究。然而，对含多面体硼烷类化合物的NLO性质研究还是相对较少，正处在起步阶段。而寻找有效的方法提高分子的二阶NLO响应，以及增强其物理性能，一直以来都是NLO材料研究的核心问题之一。随着NLO材料的多功能化，具有开关效应的NLO材料成为目前的研究热点。而硼簇化合物，尤其是金属杂硼烷的电化学性质使得这类化合物可以通过氧化还原途径控制NLO响应的开关。极化率值、超极化率值是直接衡量NLO材料性能优劣的标准，因此运用合适的量子化学方法以及寻找合理的泛函和基组计算NLO分子的极化率和超极化率值是非常重要的。基于多面体硼簇灵活可调的电子性质和独特的成键方式，通过对多体面碳硼烷和金属碳硼烷分子电子结构和二阶NLO性质进行系统的研究，从理论上揭示此类化合物产生二阶NLO响应的微观机理，为优化其二阶NLO响应，以及筛选具有较大二阶NLO响应的多功能材料提供可靠的理论依据，同时指导实验合成。本论文以碳硼烷、金属碳硼烷为模版设计系列NLO分子体系，采用密度泛函理论(DFT)和含时密度泛函理论(TDDFT)方法，结合有限场(FF)或解析求导法对其NLO性质进行理论研究。目的在于：(1)了解碳硼烷和金属碳硼烷的电子结构和化学键性质；(2)寻找合适的DFT方法计算含有碳硼烷或金属碳硼烷化合物的NLO响应；(3)讨论这类化合物的氧化还原过程引起NLO性质变化的规律，指导实验对NLO响应进行调节，以实现NLO的开关效应。本论文第一章对硼簇化合物的骨架结构、电子结构，以及相关的潜在应用进行了简要介绍，同时也对NLO的原理、实验研究、理论设计的发展现状进行了总结。第二章对计算NLO系数的方法做了简要的介绍和说明，以及对理论设计NLO材料应注意的问题进行简单总结。之后是本论文工作的主要部分，包括以下四个方面：(1)设计系列卟啉或扩展卟啉桥连夹心金属碳硼烷和电子给受体基团的化合物，采用DFT方法和TDDFT方法对其NLO性质进行计算。由于扩展卟啉可以发生可逆的氧化还原反应，因此还计算了体系还原态的NLO响应。为了寻找合理计算NLO系数的方法，并采用DFT方法中的纯泛函、杂化泛函长程校正泛函、以及从头算(ab initio)方法进行比较。2.由于二维NLO材料具有比一维NLO材料更优秀的性能设计了具有二维电子结构(D-π-A-π-D和A-π-D-π-A)的双层夹心金属碳硼烷Cp2Co2C2B3H5衍生物。由于电子给受体基团的位置不同，使得这类化合物的构型有Λ-型和W-型，文中主要讨论不同构型引起的NLO响应。3.采用DFT方法和TDDFT方法，对花生型金属碳硼烷[Ni(C2B9H11)2]的NLO性质进行理论研究。由于这类化合物可以通过光激发或氧化还原发生结构旋转，重点研究了结构旋转对NLO响应带来的影响进而是否具有NLO开关效应。为了增强体系的NLO开关效应，在实验合成的基础上，对其C和B位置上的功能化衍生物的NLO性质也做了相关探索。4.由有机胺桥连(碳)硼烷和六钼酸盐两个无机簇合物得到的系列化合物，由于碳硼烷上的不同B和C顶点和有机胺相连时引起的电子效应不同，采用ADF程序中的RESPONSE模块，利用TDDFT方法对其二阶NLO响应进行计算，并与六钼酸盐的有机胺衍生物进行比较来寻找它们之间的差异起源。另外，B-碳硼烷基和C-碳硼烷基化合物之间NLO性质差异也被研究并解释。更多还原

【Abstract】 Boron cluster compounds represent distinctive covalent species with a uniquemolecular architecture, nonconventional cluster bonding, and unusual chemistry. Dueto the rich variety, unique electronic structure, and excellent chemical stability,potential applications of this species are enormous, such as solvent extraction ofradionuclides, electrolyte, homogeneous catalysts, medicine, and so on. Addition ofhigh thermal stability, transparency in UV region, high delocalization and polarizableelectron, the boron cluster can be the candidate of nonlinear optical (NLO) materials.Especially, the NLO properties of polyhedral borane, heterborane andmetalloheterborane have been concerned and studied experimentally and theoretically.However, this respect is few and still in early stage. Importantly, one of core issues ofNLO materials is searching good methods to enhance the molecular second-orderNLO response and physical performance. With the development of multi-function ofNLO materials, the switchable effect becomes a research focus. For the boron cluster,especially the metalloheterborane, the electrochemical characters determine theirpotential ability on switchable NLO materials controlled by redox. Because the valueof hyperpolarizability is the criterion of measuring the NLO materials, rationalcomputational techniques and functionals are important for evaluating thehyperpolarizability. Based on the electronic properties and unique bonding of thepolyhedral carboranes and metallocarboranes, we will investigate the electronicstructures and NLO properties of this species to have an insight into the mechanism ofNLO responses. This work should provide rational theoretical reasons for optimizingthe NLO responses and further selecting the excellent multi-functional NLO materials,and guide the experimental synthesis.In the present thesis, designing and evaluating the NLO molecules containingcarborane or metallocarborane by employing density functional theory (DFT) andtime-dependent DFT (TDDFT) combined with finite field (FF) or analytic derivatemethods. The purpose of this thesis is that:(1) to understand the electronic structuresand properties of polyhedral carboranes and metallocarboranes.(2) to explore rationalDFT functionals to calculate the NLO responses of polyhedral carboranes andmetallocarboranes.(3) to obtain the switchable NLO molecules based on the experiment methods.The first part of this thesis is a review of skeleton structure, electronic structure,and related potential applications for boron cluster compounds, addition of theprinciple, experimental and theoretical studies of NLO property. The second part is anbrief introduction of computational methods calculating NLO coefficients, and somequestions needing attention on theoretical design of NLO materials. Subsequent partis the main body of this thesis, and it includes the following four sections:(1) We have designed a series of pull-push Cp*CoEt2C2B4H3-expanded(metallo)porphyrins compounds and employed DFT and TDDFT methods to calculatethe NLO properties. Due to the reversible redox of expanded (metallo)porphyrins, wehave also the NLO responses of reduced forms. To determine the rational functionalfor evaluating NLO coefficients, pure DFT, hybrid DFT, long-range (LC) DFTfunctionals and ab initio were used.(2) Two-dimensional (2D) NLO materials possess more excellent performancethan one-dimensional NLO materials. We thus designed a series of2D NLOmolecules containing sandwich metallocarborane Cp2Co2C2B3H5with D-π-A-π-D orA-π-D-π-A model. According to the positions of acceptor and donor, we named thestudied molecules as Λ-and W-shaped and discussed their NLO responses.(3) Using DFT and TDDFT methods, we have theoretically investigated the NLOproperties of sandwich metallocarboranes [Ni(C2B9H11)2]. The rotation ofconfigurations of this species can be controlled by redox or photon excitation, andthus we studied the switchable effect on NLO response. To obtain a remarkableswitchable effect, we also explored the NLO responses of C, B-functionalizedderivates based on experimental synthesis.(4) A series of novel hybrid have been designed by organoimido bridging the(car)borane and hexamolybdate clusters. The electronic effects of the carboranylgroup depend on the position of the substituent in the carborane cage. We employedthe RESPONSE model in ADF program to calculate the second-order NLO responsesof studied compounds. The NLO properties of the hybrids were compared with that ofhexamolybdate-organoimido, and the differences between C-carboranyl andB-carboranyl on NLO responses were also discussed.更多还原