偶氮苯化合物的合成及其光致异构化研究

发布时间：2019-03-05 12:27

【摘要】：偶氮苯化合物是一种典型的光致变色材料,其光致异构化特性在诸多领域得到了广泛的应用。本文设计合成了五种不同结构的偶氮苯衍生物,着重探讨了其结构对光谱性能的影响。在此基础上,将偶氮苯的光致异构化性能应用于无机量子点以及石墨烯的改性。首先,我们采用了重氮偶合法合成了五种不同的偶氮苯衍生物,其中包括含有强吸电子基团、给电子基团以及含有不同数目偶氮基的化合物。合成过程中也涉及到氨基的氧化、氨基保护以及硝基还原。目标产物通过红外和紫外-可见吸收光谱进行了分析表征。其次,偶氮苯化合物的光致异构化性能主要与分子结构上取代基的性质有关。我们分别对含有吸电子基团-NO2、给电子基团-NH2以及不同数目偶氮基的化合物的光致异构化动力学行为进行了比较研究,发现不同性质的取代基对化合物光致异构化性能的影响不同,吸电子基团具有抑制作用,而多个偶氮基团的作用较为复杂。此外,溶剂的极性以及酸性对偶氮苯化合物的紫外-吸收光谱存在一定的影响。极性溶剂的极化作用影响了分子中电子跃迁的能量差,导致谱带的最大吸收波长(λmax)发生位移；介质中的H+使分子中的生色团质子化,化学键发生改变,从而产生酸致变色现象。然后,在对无机量子点的改性方面,我们将具有良好光致异构化性能的4-氨基偶氮苯与巯基丙酸(MPA)通过酰胺化缩合反应制成新的偶氮苯化合物(MPAA),并通过1HNMR、FTIR以及UV-Vis光谱对其结构进行表征分析。将这种化合物与MPA共同作为配体制备了CdSe-MPAA量子点。与单纯以MPA作为配体合成的CdSe量子相比,在紫外-可见吸收光谱中,新型量子点具有光致异构化特性；在荧光光谱中,偶氮苯分子的加入对CdSe量子点的荧光起到了猝灭效应。最后,在对氧化石墨烯(GO)功能化方面,我们利用了GO表面上大量的极性亲水基团-COOH和4,4’-二氨基偶氮苯通过酰胺化缩合反应,将偶氮苯分子接枝到GO表面,制成GO-Azo杂化材料。这种材料同时具有GO的单片层基本结构和偶氮苯生色团的光致异构化行为。功能化的GO-Azo的电导率与GO相比显著提高,并在紫外光作用下的电导率逐渐下降,说明可将其应用于光控电导率研究。
[Abstract]:Azobenzene compounds are a typical photochromic material, and their photoisomerization properties have been widely used in many fields. In this paper, five azobenzene derivatives with different structures have been designed and synthesized, and the effect of their structures on the spectral properties has been discussed emphatically. On this basis, the photoisomerization of azobenzene was applied to the modification of inorganic quantum dots and graphene. Firstly, we synthesized five different azobenzene derivatives by diazo coupling method, including strong electron-absorbing group, donor group and compound containing different number of azobenzene groups. The synthesis process also involves the oxidation of amino group, protection of amino group and reduction of nitro group. The target products were characterized by IR and UV-vis absorption spectra. Secondly, the photoisomerization properties of azobenzene compounds are mainly related to the properties of substituents in molecular structure. The photoisomerization kinetics of compounds containing electron-absorbing group-NO2, donor group-NH2 and different number of azo groups were compared. It is found that different substituents have different effects on the properties of photoisomerization of compounds, and the electron-absorbing groups have inhibitory effect, while the effects of several azo groups are more complex. In addition, the polarity of the solvent and the UV-absorption spectra of azobenzene compounds were affected to a certain extent. The polarization of polar solvent affects the energy difference of electron transition in molecule, which results in the shift of maximum absorption wavelength (位 max). The H in the medium makes the chromophore in the molecule protonated and the chemical bond changes, resulting in an acid-induced discoloration phenomenon. Then, in the modification of inorganic quantum dots, 4-aminoazobenzene with mercaptopropionic acid (MPA), which has good photoisomerization properties, was synthesized by amidation condensation reaction to form a new azobenzene compound (MPAA), and passed 1HNMR. The structure was characterized by FTIR and UV-Vis spectra. The CdSe-MPAA quantum dots were prepared by co-using this compound with MPA as ligand. Compared with CdSe quantum synthesized only with MPA as ligand, the novel quantum dots have the properties of photoisomerization in UV-vis absorption spectra, and the fluorescence of CdSe QDs is quenched by the addition of azobenzene molecules in the fluorescence spectra. Finally, in the aspect of (GO) functionalization of graphene oxide, we used a large number of polar hydrophilic groups-COOH and 4,4-diaminylazobenzene on the surface of GO to graft azobenzene onto GO surface by amidation condensation reaction. GO-Azo hybrid material was made. This material has both the basic lamellar structure of GO and the photoisomerization of azobenzene chromophore. The conductivity of functionalized GO-Azo is significantly higher than that of GO, and the conductivity decreases gradually under the action of ultraviolet light, which indicates that it can be applied to the study of photo-controlled conductivity.
【学位授予单位】：中国海洋大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：O625.65

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