【作者】 Muhammad Ramzan Saeed Ashraf Janjua；

【导师】 苏忠民；

【作者基本信息】 东北师范大学 ， 物理化学， 2010， 博士

【摘要】 通过超分子排列方法用各种有机配体设计和合成大量的结构奇特的杂化多金属氧酸盐（POMs）引起了广泛关注,并加快了这类材料的发展。我们使用量子化学方法设计一些更多所谓阴阳离子盐和主客体化合物的杂化材料,这些材料具有活性的电荷磁性质并能够发生解吸附-再吸附过程。多酸可以接受或释放一定数量的电子,并保持结构的完整性,从而充当很好的多电子传播器。这一特性可以使无机有机杂化的多酸化合物活跃在电极修饰和电催化研究中。这些基于多酸的无机有机杂化材料在电学,光学和信息技术领域拥有巨大的发展前景。我们已经对有机无机杂化的功能材料进行了一系列的研究。本论文中,采用量子化学方法中的时间依赖的密度泛函方法（TDDFT）对基于多酸的杂化材料的电子性质、偶极极化率、偶极距变化（Δμ）、态密度和二阶非线性光学响应（NLO）进行研究。1.第一部分是对功能材料的有价值的补充,在这里,电荷转移方向通过有机配体的链长的改变而改变,六钼酸盐到有机胺的电荷转移是增加这种功能材料的NLO响应的主要决定因素。原为电子受体的多酸簇变成电子供体,而有机胺作为电子受体,它们通过π共轭桥连接实现电子转移,而这种多酸作为电子供体的材料为功能化材料化学开辟了新的领域。本章对一维（D-D-A-A）,二维和三维非线性光学材料的理论设计证明有机无机杂化的多酸衍生物具有很大的NLO响应。2.第二部分主要报道了二氮烯苯基取代的多酸化合物可调的NLO性质,并且可以提供一种新途径设计并合成基于有机无机杂化多酸衍生物的高效功能材料。含有有机配体的多酸簇改变了体系电荷转移特征,实现了功能材料的新领域。本章采用DFT方法研究二氮烯苯基取代的六钼酸盐的非线性光学性质。二氮烯苯基取代的作为电子供体提高了第一超极化率,NLO性质通过配体的共轭链的增长而增加。因此,可以调节二氮烯苯基取代的六钼酸盐的NLO行为使之成为高效的NLO材料。3.六钼酸盐中衍生物有机部分中三联吡啶的引入使之成为超分子化学中有效的分子前驱体。将多酸簇桥联到悬挂的三联吡啶上可以产生供受体化合物并成为潜在的非线性光学材料。本章研究发现改变三联吡啶上的不同取代基可以改变体系的非线性光学响应,并为实验合成新型的功能材料提供合成方案。轨道分析表明多酸和三联吡啶的电荷转移程度在二维的有机金属/多酸杂化体系中增加。这次研究为研究三联吡啶取代的六钼酸盐的大的NLO性质提供了重要的思路。4.本章研究发现,有机胺取代的六钼酸盐衍生物的NLO响应可以从218.61×10^-30 esu增加到490.10×10^-30 esu。本章采用TDDFT方法研究了有机胺取代的六钼酸盐衍生物的偶极极化率和二阶非线性光学响应。具有吸电子能力的F原子的引入在调节这类有机无机杂化的多酸化合物的NLO响应起到很重要的作用,尤其化合物6[Mo6O18（NC16H8F2（CF3）2I）]2-的静态二阶极化率（βvec）达到490.10×10^-30 esu。因此我们研究的体系可以成为很好的NLO可控的光学材料。对βvec的主要贡献分析显示沿着z轴从多酸到有机配体的电荷转移由于末端苯环上F原子的加入而提高,并且电荷转移从头部的多酸向末端的氟化的苯环移动。计算的βvec值可以通过在有机胺基团末端的苯环上引入不同的卤素原子进行调节。此外,两个三氟甲基在有机胺末端苯环上I原子两侧的取代极大影响了体系的非线性光学响应,并且使从多酸到有机胺配体的电荷转移随之增加。不同卤素原子的取代给体系的NLO响应的改变带来连锁反应。由于末端基团吸电子能力的增加,体系1到6的NLO响应按照以下顺序增加:CH3 （1） < F （2） < Cl （3） < Br （4） < I （5） < CF3 （6）。因此,我们可以利用这种连锁反应去增大电子受体的能力从而提高对体系NLO响应的影响程度。因此,本章的研究为调节有机胺取代的六钼酸盐的NLO性质提供了有力的研究手段。5.三联吡啶取代的六钼酸盐的非线性光学响应可以从体系1的886.55×10^-30 esu增大到体系7的4622.92×10^-30 esu。本章采用TDDFT方法对三联吡啶取代的六钼酸盐衍生物的偶极极化率和二阶非线性光学性质进行了研究。量子力学计算发现体系7[Mo₆O₁₈(N₄C₂₅H₁₄（CF₃）₂ （CN）₂)]^2-在所有体系中的NLO响应最大。吸电子基团（F, Cl, Br, I, CF3和CN）在三联吡啶末端的引入使电荷转移沿着z轴从多酸簇向三联吡啶转移,从而导致体系7产生更有效的二阶NLO响应。通过取代而造成分子组成上的微小改变却能够导致NLO上极不相称的巨大变化,这种变化称为蝴蝶反应。6.本章采用DFT方法研究了钒硅酸盐[Si8V14O50]12-以及相关离子,并对杂原子GeIV, PV, AsV和SiIV的变化对体系的电子和氧化还原性质的影响进行了研究。用GeIV,AsV和PV取代SiIV为实验合成其他的类似钒硅酸盐,钒锗酸盐,钒磷酸盐和钒砷酸盐以及他们的杂多阴离子衍生物提供了一条新途径。更多还原

【Abstract】 The design and synthesis of novel compounds hybridizing polyoxometalates （POMs） with a variety of organic ligands through supramolecular arrays have aroused particular interest and accelerated the development of this new kind of materials. We have quantum chemically designed these hybrid compounds, which are generally called anion-cation salts and host-guest solids, and which can possess active electrical and magnetic properties as well as desorption-readsorption properties. POMs can accept and release a certain number of electrons without decomposition, thus serving as multielectron relays. This attribute has made these inorganic-organic hybrids very attractive in electrode modification and electrocatalytic research. These POM-based inorganic-organic materials have immense potential in the field of electronics, photonics, and information technology. We have found new and novel insights into the properties of inorganic-organic hybrid functional materials.In this thesis, the quantum chemical approach has been carried out to investigate electronic properties, dipole polarizabilities, change of dipole moments （Δμ）, density of states, and second-order nonlinear optical （NLO） properties of POM-based inorganic-organic hybrid functional materials by employing time dependent density functional theory （TDDFT）.1- The first research report is a valuable addition in the field of advanced functional materials where the direction of charge transfer had been altered by changing the length of organic ligand in which hexamolybdates-to-organoimido charge transfer was a vital determinant to increase the NLO response of proposed functional material. The electron accepting property of POM cluster has been changed as it acts as a donor and organoimido ligand acts as an acceptor （D-bridge-A） via charge-transport property ofπ-conjugated bridge which has established the identity of POM as a donor as well in a rigorous way and has opened new horizons in the field of functional material chemistry. Here the quantum design of 1-D （D-D-A-A）, 2-D, and 3-D nonlinear optical materials have also been suggested based on inorganic-organic hybrids with remarkably large NLO responses.2- In second research report the tunable NLO behavior of aryldiazenido hexamolybdates has been demonstrated and it may provide a new means for experimentalists to design high-performance functional materials based on inorganic-organic hybrid composites. The inclusion of organic ligand in inorganic cluster （POM） has changed the nature and direction of charge transfer which might be a surprising addition in the field of functional materials. The nonlinear optical properties of aryldiazenido hexamolybdates were studied by DFT analysis. An electron donor in the aryldiazenido ligand enhanced the first hyperpolarizability, and the NLO properties could be improved strikingly by increasing the conjugation path of the ligand. Thus, the NLO behavior of aryldiazenido hexamolybdates can be tuned for the design of high-performance NLO materials.3- In third research report the inclusion of the terpyridine moiety （organic pendant） in substituted hexamolybdates （POM） is shown to be important because they may act as efficient molecular precursors for application in supramolecular chemistry. The polyoxomolybdate cluster connected to pendant terpyridine units via a bridging group to generate donor-acceptor complexes suitable for applications as non linear optical materials. The study varied the substituents pendant to the terpyridine ligand and the results provide synthetic targets for the development of new functional materials with improved responses through the incorporation of various substituents. The orbital analysis shows that the degree of charge transfer （CT） between POM and terpyridine segment was increased in 2D and organometallic/POM hybrid systems. This investigation provides important and thought provoking insight into the robustly large NLO properties of terpyridine substituted hexamolybdates.4- In this work, NLO response of organoimido-substituted hexamolybdates has been tuned from 218.61×10^-30 esu to 490.10×10^-30 esu. The dipole polarizabilities and second-order nonlinear optical （NLO） properties of organoimido derivatives of hexamolybdates have been investigated by using time-dependent density functional response theory （TDDFT）. The electron with drawing ability of F （fluorine） has played an important role to tune second-order NLO response in this class of organic-inorganic hybrid compounds particularly system 6 [Mo6O18（NC16H8F2（CF3）2I）]2- with the static second-order polarizability （βvec） computed to be 490.10×10^-30 esu. Thus, our studied systems have feasibility to be excellent tunable second-order nonlinear optical materials. The analysis of the major contributions to theβvec value suggests that the CT from POM to organic ligand （D–A） along the z-axis has been enhanced with addition of F atoms at the end phenyl ring which directs head （POM） to tail （fluorinated ring） charge transfer. The computedβvec values have been tuned by incorporation of different halogen atoms at the end phenyl ring of organoimido segment. Furthermore, substitution of two trifluoromethyl （-CF₃） groups sidewise along with iodine （I） at the terminus of end phenyl ring in organoimido ligand has striking influence to tune the optical nonlinearity as CT from POM to organoimido ligand was significantly increased. The systematic small changes in molecular composition by substitution of different halogen groups cause ripple effect which leads to tuning the NLO response; the so-called“ripple effect”catches this point nicely. The NLO response of systems （1-6） has been increased by increasing the strength of terminal group in the following order: CH₃ （1） < F （2） < Cl （3） < Br （4） < I （5） < CF3 （6）. So, we can use the principle of Ripple Effect to magnify the actions of electron acceptors and their effects on NLO responses of studied systems. Thus present investigation provides thought provoking insight into the tunable NLO properties of organoimido substituted hexamolybdates. 5- A dramatic increase in second-order NLO response of terpyridine-substituted hexamolybdates has been observed from 886.55×10^-30 esu （system 1） to 4622.92×10^-30 esu （system 7）. The dipole polarizabilities and second-order nonlinear optical （NLO） properties of terpyridine derivatives of hexamolybdates have been investigated by using time-dependent density functional response theory （TDDFT）. The Quantum mechanical design suggests that [Mo₆O₁₈(N₄C₂₅H₁₄（CF₃）₂ （CN）₂)]^2- （system 7） is the best choice among all studied systems to improve nonlinearity. The electron withdrawing ability of electron acceptor groups （F, Cl, Br, I, CF3 and CN） at the end of terpyridine ligand directs the CT from POM-cluster to terpyridine segment along the z-axis which leads to an efficient second-order NLO molecular designing of our studied systems. These small changes in molecular composition by substitution may have disproportionally huge effects on the NLO properties, the so-called“butterfly effect”catches this point nicely.6- In this work, DFT calculations were carried out on vanadosilicate [Si8V14O50]12- and other related anions, the effect of substitution of Ge^IV, P^V, As^V with Si^IV on the electronic and redox properties was investigated. The substitution of Si^IV with Ge^IV, P^V, and As^V may open up possibilities for the experimentalists to synthesize other mimicked vandosilicates, vanadogermenates, vanadophosphates and vanadoarsenates as well as their heteropolyanions respectively.更多还原