【作者】 杨宝珠；

【导师】 张红星；

【作者基本信息】 吉林大学 ， 物理化学， 2010， 博士

【摘要】 过渡金属配合物发光性质的量子理论研究不仅对无机新型光学材料的探索和设计具有重要指导意义,而且本身就是极其重要的理论课题。本文采用理论方法对一系列平面四配位d8过渡金属配合物进行了研究,主要成果如下: 1.用DFT理论和CIS方法研究了四种环金属Au(???)配合物的结构和光谱性质。结果表明,配合物在基态的几何结构与实验值符合的很好,在配合物的基态前线分子轨道中,金属的原子轨道成分很小,因此d?d态非辐射跃迁不能发生。随着吡啶基的位置和数量的变化,吡啶基的接受电子能力按照1<2<4<3的顺序增强,HOMO–LUMO能隙相应的降低。配合物的最低能吸收和发射波长按照1<2<4<3的顺序红移。2.研究了三个炔基Pt0配合物的几何结构和光谱。计算结果显示,最低能的吸收都是具有MLCT和ILCT性质,这些吸收不仅是来自Pt→PPh3和Pt→acetylene上的跃迁,还有一部分是来自Pt→Ph上的跃迁。很多研究人员认为3MLCT跃迁来自于Pt→acetylene(π*)轨道,但根据我们的研究,配合物1?3的3MLCT跃迁全部是由Pt→Ph(π*)跃迁产生。随着磷原子的给电子能力和炔基的共轭效应增加,配合物的发射能相应的降低,并且发射能主要由磷原子的给电子能力和炔基的电子结构决定的。3.研究了三个N^C^N配体的Pt(??)配合物的几何结构、吸收和发射光谱。结果表明,吡啶被吡唑取代对基态几何结构的影响很小。随着吡啶基被吡唑基取代,N原子的给电子能力按照1>2>3的顺序降低,吡唑基使LUMO轨道不稳定,但是对HOMO轨道的影响很小。配合物1?3的最低能吸收和发射发生蓝移。对于芘及其衍生物的研究表明,芘的发光性质可以被重原子改变。随着重原子序数和原子数目的增加,发射光谱发生红移。配合物1和3的最低能吸收具有LMCT、ILCT、和LLCT性质,而配合物2的最低能吸收具有ILCT性质。三个配合物的最低能发射具有3ILCT性质。更多还原

【Abstract】 Because of its characteristics and function such as electricity, light, sound, magnetism and heat etc., functional material has been paid most attention to in the last five decades. The achievement in designing and developing functional material not only has greatly promoted the revolution of scientific technology in the late 20th century, but also will act as the foundation of the development of the advanced scientific technology in future. As one of the most important parts of the design of functional materials, the design of optical materials has also been focused on by physicist, chemist and material scientist all the time. Recently, a great deal of experimental work on the electronic absorption and emission of transition metal complexes has been performed to seek inorganic optical material that exhibits intensive luminescence in the visible region. The absorption and emission of transition metal complexes usually are related to the charge transfer between d orbitals of metal and s/p orbitals of metal or ligand. Because such an electronic absorption in the ultraviolet region usually conduct the corresponding emission in the visible region, transition metal complexes are one of the most excellent candidates to serve as visible-region optical material. The advanced technique applied in experiments greatly promotes the development of modern computational chemistry. On one hand, the comparison between calculation and experiment can test the reliability and accuracy of electronic structure theory, showing the dependence of theory on experiment; on the other hand, to develop the electronic structure theory is to support and/or supplement the known experimental results, and further to predict the potential results, indicative of theoretical forward looking and independence In the paper, combining the benefits of various quantum chemical computational methods, we systematically studied luminescent properties, ground- and excited-state electronic structures of transition metal complexes and obtained the following main results:1. The electronic structures and spectroscopic properties of the four tridentate cyclometalated Au(???) complexes [Au(C^N^C)C≡CPh] (1), [Au(N^C^C)C≡CPh] (2), [Au(N^N^C)C≡CPh]+ (3), and [Au(N^C^N)C≡CPh]+ (4) [HC^N^CH = 2,6 -diphenylpyridine, N^CH^CH = 3-(2-pyridyl)biphenyl, N^N^CH = 6-phenyl-2,2′- bipyridine, N^CH^N = 1,3-di(2-pyridyl)benzene] were calculated to explore their spectroscopic nature. The geometry structures of 1?4 in the ground and excited states were optimized under the density functional theory (DFT) and the single-excitation configuration interaction (CIS) level, respectively. As revealed from the calculations, the optimized bond lengths and bond angles for the complexes in the ground state are in general agreement with the corresponding experimental values. The composition of Au in frontier molecular orbital is very small, therefore the d-d excited state is unavailable and does not lead to nonradiative decay. The absorptions for 1?4 in CH3CN solution were also calculated, when the solvent is changed from CH2Cl2 to CH3CN, the characters of absorptions are completely unchanged. But the lowest-energy absorptions in CH3CN solution for 1?4 have slight change in energy, which are red-shifted 0.02, 0.02, 0.04, and 0.03 eV, respectively. With the variation in position and the number of pyridine, the electron-donating ability of N atoms increases in the order 1 < 2 < 4 < 3, and the HOMO?LUMO energy gap are lowered correspondingly. The lowest-energy absorptions and emissions wavelength of 1?4 are red-shifted in the order 1 < 2 < 4 < 3. The lowest-lying absorptions for 1?4 are all derived from the LLCT. The lowest-energy emissions for 2 and 3 come from the 3LLCT transition perturbed by some 3ILCT transition, whereas the emissions for 1 and 4 are attributed to the 3ILCT and 3LLCT/3LMCT, respectively.2. Electronic structures and spectroscopic properties of (L)Pt[(1,2-η2)–Ph–(C≡C)n–Ph] (n = 1, L = (PPh3)2 (1), n = 1, L = dppp (2), and n = 2, L = (PPh3)2 (3) ) are studied by the ab initio and DFT methods, respectively. The ground- and excited-state structures are optimized by the B3LYP and CIS methods, respectively. At the TD-DFT level with the PCM model, the absorption and emission spectra in solution are obtained. The calculation reveals that the lowest-energy absorptions are attributed to the MLCT/ILCT transitions, whereas the lowest-energy emissions are assigned as a 3MLCT/3ILCT character. The absorptions are not only attributed to Pt→PPh3 and Pt→acetylene but also Pt→Ph and we demonstrates that the MLCT transitions in these kinds of Pt0 complexes dominate the low-energy-region absorption spectra. the HOMO?LUMO energy gaps of 3 is smaller than 1 and 2. This is due to the strongπ-conjugation effects in 3. In comparison with 2, the PPh3 in 1 is a strong electron-acceptor and weaker electron–donor than the dppp in 2. So the lower lying absorption energies are in the order 1>2>3. With increasing theπ-conjugation of alkyne and electron-donating ability of the phosphane, the emission energy is lowered correspondingly.3. The electronic structures and spectroscopic properties of the three tridentate cyclometalated Platinum(??) complexes PtL1Cl [L1 =1,3-di (2-pyridyl) -5-methy l-benzene] (1), PtL2Cl [L2 =1-(2-pyridyl)-3-(1-pyrazolyl) -5-methyl-benzene] (2), and PtL3Cl [L3 = 1,3-Bis(1-pyrazolyl)-5-methyl-benzene] (3) were calculated to explore their spectroscopic nature. As revealed from the calculations, there are minor differences in bond angles for 1?3 and the replacement of pyridyl by pyrazolyl has little influence upon the ground state geometries. With the replacement of pyridyl by pyrazolyl, the electron-donating ability of N atoms decrease in the order 1 > 2 > 3, and the LUMO energy levels increase correspondingly. But the replacement has a little influenced on the HOMO energy, then the HOMO?LUMO energy gaps increase in the order 1 < 2 < 3. The lowest-energy absorptions are attributed to ILCT/MLCT/LLCT transitions, whereas the lowest-energy emissions are assigned as 3ILCT/3MLCT/3LLCT character.Two ligands 1-diphenylphosphinopyrene (1-PyP)(L1), 1,6–bis(diphenyl- phosphino)- pyrene (1,6-PyP) (L2) and their cyclometalated complexes [Pt(dppm)(1-PyP-H)]+ (1), [Pt2(dppm)2(1,6-PyP-H2)]2+ (dppm=bis(diphenyl- phosphino)methane (2), and [Pd(dppe)(1-PyP-H)]+ (dppe=bis(diphenyl- phosphino)ethane) (3) are investigated theoretically to explore their electronic structures and spectroscopic properties. As revealed from the calculations, the lowest-energy absorptions of 1 and 3 are attributed to the mixing LMCT/IL/LLCT transitions, while that of 2 is attributed to the IL transition. The lowest-energy phosphorescent emissions of the cyclometalated complexes are attributed to coming from the 3ILCT transitions. With the increase of the spin-orbit coupling (SOC) effect, the phosphorescence intensities and the emissions wavelength are correspondingly increased.更多还原