【作者】 吴美红；

【导师】 刘举正； 王明亮；

【作者基本信息】 东南大学 ， 应用化学， 2005， 硕士

【摘要】 近年来,分子内电荷转移化合物的研究越来越受到人们的重视,因其分子内含有电子给体与电子受体,容易发生光诱导分子内电荷转移而呈现出一些特有的光学性质,被广泛研究并应用于发光材料、光电导材料、非线性光学材料以及荧光探针等领域。随着纳米科学技术的研究逐渐从无机领域拓展到有机领域,分子内电荷转移化合物的研究也有了崭新的发展方向。在介观领域,对分子内电荷转移化合物超微粒进行研究,可以加深本文理解该类化合物在材料应用中的许多基本过程和现象,对于进一步开发和利用分子内电荷转移化合物有着重要意义。目前,分子内电荷转移化合物的基础研究已跟不上材料应用研究发展的步伐,特别是对其超微粒方面的研究还处于刚刚起步阶段,许多因分子间和分子内相互作用引起的光物理行为还有待人们作深入的研究。本论文主要通过对分子内电荷转移化合物溶液和超微粒的光学性质的研究,分析它们分子内和分子间发色团在基态和激发态下的相互作用对吸收光谱和荧光光谱的影响,为材料设计提供坚实的理论基础。本论文工作的具体内容如下:1、合成了下列几种分子内电荷转移化合物:5-(9-蒽基)-1-苯基-3-对硝基苯基吡唑啉、4,4′-二-[5(1,3-二苯基-2-吡唑啉基)]-苯、1,3,5-三苯基-2-吡唑啉化合物、4-(N,N-二乙氨基)苯甲醛对硝基苯腙、对硝基苯甲醛苯腙、N,N,N′,N′-四苯基联苯二胺、2,3-二氢-4(1H)-喹啉酮以及9-苯乙烯蒽等。利用再沉淀法分别制备了它们的超微粒分散体系。2、研究了2,3-二氢-4(1H)-喹啉酮分子在不同浓度、不同极性溶液中吸收光谱和荧光光谱等光学性质,发现该化合物是一强荧光发射化合物,其激发态与基态偶极距变化较大。在激发态时发生了分子内电荷转移,因此荧光光谱随溶剂极性的增大,发射峰不断红移。3、通过对吡唑啉类化合物溶液及超微粒的研究,发现该类分子由于5位芳香取代基的不同,产生了分子内非共轭电荷转移和分子间电荷转移的竞争,分子间的电荷转移对分子内非共轭电荷转移有抵消作用,因此呈现出了一些新的现象。例如,在5-(9-蒽基)-1-苯基-3-对硝基苯基吡唑啉超微粒中出现了吡唑啉环吸收峰的蓝移,这是本实验室首次在超微粒中发现蓝移现象,它可以用分子内非共轭电荷转移和分子间电荷转移的竞争来解释。通过对苯腙类化合物、9-苯乙烯蒽溶液及超微粒的研究,发现该两种化合物超微粒同样具有光学性质的尺寸依赖性。但是,由于分子内取代基的不同,导致超微粒中分子间相互作用也不同,有的超微粒在水分散系中可以稳定存在,如:对硝基苯甲醛苯腙、N,N,N′,N′-四苯基联苯二胺等形成的超微粒。4、本文还在国际上首次研究了混合有机超微粒分散体系的光学性质。(1)对1,3,5-三苯基-2-吡唑啉和蒽形成的混合物纳米超微粒水分散体系的光学性质研究,发现该混合有机超微粒体系低能端的吸收光谱随其尺寸的增加而增强,而相应蒽和1,3,5-三苯基-2-吡唑啉的超微粒却随尺寸的增加而减弱,表明混合有机超微粒中不同分子间发生了电荷转移。本实验通过对混合有机超微粒分散系荧光光谱的测定分析得到了一致的结果。(2)通过对对硝基苯甲醛苯腙和蒽形成的混合物超微粒分散体系吸收光谱的研究,发现形成混合物超微粒后,原来在水分散体系中稳定存在的对硝基苯甲醛苯腙吸收光谱随沉化时间的延长而发生改变,这也是分子间电荷转移的结果。更多还原

【Abstract】 Intramolecular charge-transfer compounds(ICICs) have been attracted much interest in recent years because of their possible application in luminous materials, photoconduction materials, nonlinear optical materials, fluoroprobe with electron-donating and electron-accepting structure.With the development of the nano-science and technology, research on organic supracrystals receive much attention because of their unique optical and electronic properties. So studies on ICTCs in mesoscopic field become possible and necessary. It will help seeking for new optical and electronic materials.Despite the extensive application of ICTCs, many questions and difficulties still remain in fundamental research especially for the molecular charge-transfer interaction in solvents and in their supraparticles. These interaction influences the absorption spectra and fluorescent spectra. So it is very important for understanding the photophysical behaviors in photoluminescence and electroluminescence by researching chromophore interaction intra- and inter-molecularly .1. In experiment, some ICTCs have been synthesized , such as: 5-(9-anthryl)-3-(4-nitro phenyl)-1-phenyl-2-pyrazoline, 4,4′-bis-[5(1,3-diphenyl-2-pyrazolinyl)]-benzene, 1,3,5-triphenyl -2-pyrazoline, 4-(N,N-diethylamino)benzaldehyde p-nitrophenylhydrazone, p-nitrobenzaldehyde phenylhydrazone, N,N,N′,N′-tetraphenylbenzidine, 2,3-dihydroquinolin-4(1H)-one, 9-styrylanthr -acene, etc. Then these compounds were dissolved in solvents, and some were prepared into supraparticles by repreciptation.2. The optical properties of 2,3-dihydroquinolin-4(1H)-one in solvents with different concentration and different polarities have been measured by UV-Vis spectra and the fluorescent spectra. It is found that intramolecular charge-transfer from N→Aryl→O exists in the excited state, and there are large dipole moment change between the excited state and the ground state of this compound. 2,3-dihydroquinolin-4(1H)-one compound is one of the strong light-emitting materials.3. 1,3,5-triaryl-2-pyrazoline compounds have conjugated charge-transfer in“Aryl-N-N=C -Aryl”group and nonconjugated charge transfer between the“Aryl-N-N=C -Aryl”chromophore and aryl in 5 position. By studying UV-Vis spectra of 5-(9-Anthryl)-3-(4-nitrophenyl)-1-phenyl-2 -pyrazoline supraparticles, it is found that except for the size-dependence of the optical properties, there is the competition between the nonconjugated charge-transfer and intermolecular charge-transfer interaction, and the later plays the main role in this system. Intermolecular interaction leads to hypsochromically shifte of pyrazoline chromophore, which was not found before. The size-dependence of the optical properties is also found in supraparticles consisting of 4-(N,N-diethylamino)benzaldehyde p-nitrophenylhydrazone and 9-styrylanthracene.4. The UV-Vis spectra and fluorescence spectra of mixed organic supraparticles are researched at the first time in the world. The resulting conclusion are shown that the optical properties of the mixed organic supraparticles are obviously different from that of the mixed solution and they are also different from that of the supraparticles which are formed by the same molecules. Two results are obtained as follows: (1) Charge-transfer is found between the two molecules in 1,3,5-triphenyl-2-pyrazoline and anthracene mixture supraparticles. (2) Intermolecula -r charge-transfer interaction also exists in the mixture supraparticles of p-nitrobenzaldehyde phenylhydrazone and anthracene.更多还原