【作者】 陈颂；

【导师】 王建秀； 宋相志；

【作者基本信息】 中南大学 ， 化学， 2013， 博士

【摘要】 摘要：有机荧光染料,广泛应用于蛋白质、核酸、脂质、碳水化合物、毒素、激素和其它生物分子的荧光标记,对于生物医学的发展具有重要的意义。据统计,85%以上的荧光染料属于“供体-受体”型染料,其结构中存在着电子供体和电子受体。大部分荧光染料的荧光量子效率(Φ)都低于100%的理想值,关于其荧光淬灭的机理,目前“扭曲的分子内电荷转移理论(TICT理论)”被大家普遍所接受,人们认为TICT激发态的形成是导致荧光淬灭的主要原因。然而,现有的TICT理论还不能对众多的染料分子结构与性能之间的关系做出全面的解释,尚有许多方面需要完善,例如TICT理论中的体积效应、染料分子中供体与受体之间的相互影响等等。因此,深入研究TICT理论,对设计性能优良的荧光染料具有重要的理论意义。罗丹明染料是一种典型的“供体-受体”型荧光染料,具有优良的光物理和光化学性能。本论文以罗丹明染料为母体,合成了一系列不同结构的罗丹明荧光染料,并对染料的光物理、光化学性能进行测试。通过实验结果和理论计算,研究荧光染料结构与性能之间的关系,以期加深对TICT理论的理解。本论文的研究内容如下：1.通过对胺基供体的改造(刚性、柔性以及电负性),合成了7种对称和不对称胺基供体的罗丹明荧光染料,同时测试了染料的荧光性能,并探讨了两个胺基供体之间、胺基供体与受体之间的相互作用对罗丹明荧光染料分子荧光性能的影响。研究结果表明,胺基供体结构的刚性可以有效阻止TICT激发态的形成,进而提高荧光染料的荧光寿命；在TICT激发态时,正电荷主要集中在罗丹明分子的两个胺基上,正电荷的分布与胺基供体的供电能力密切相关,供电能力强的胺基承担正电荷较多,供电能力弱的胺基承担电荷较少。因此,不对称罗丹明荧光染料的荧光寿命与供电能力强的胺基端的刚柔性有着密切的关系,刚性结构能够有效提高染料的荧光寿命,而柔性结构有助于TICT激发态的形成,使染料的荧光寿命下降。2.以萘磺酸酐为原料成功合成了7种新型的罗丹明荧光染料,并对其吸收光谱、荧光光谱以及不同溶剂、不同温度下的荧光寿命进行了测试。探讨了以萘磺酸酐和苯磺酸酐为原料合成的两种罗丹明染料荧光性能之间的差异。研究表明,由于萘磺酸基的空间位阻效应和所带负电荷的电子效应,致使TICT激发态不易生成,从而使染料的荧光性能得以改善。新合成的7种染料与以一个苯环为受体的传统罗丹明染料相比,其荧光寿命提升了38%。3.设计合成了9种具有不同体积大小的仲胺基为电子供体的罗丹明荧光染料,同时对染料的荧光寿命进行了测试。研究结果表明,仲胺基的体积大小可以有效影响染料分子中TICT激发态的形成,进而影响荧光染料的荧光寿命。在TICT激发态的形成过程中,体积较大的烷基胺旋转慢于体积较小的烷基胺,因此可以有效抑制TICT激发态的形成,提高染料分子的荧光寿命。该研究结果进一步证实了TICT理论中"TICT激发态的形成伴随着供体烷基胺的旋转"这一观点的正确性。4.利用TICT理论,设计合成以氮杂环丁烷、二甲胺和吡咯烷作为电子供体的罗丹明染料AZESR、TMSR和PYRSR。通过对染料的吸收光谱,发射光谱,荧光量子产率和荧光寿命进行了测试。研究结果表明,AZESR染料的荧光性能明显优于TMSR和PYRSR罗丹明染料。AZESR染料具有较高的荧光量子产率和荧光寿命,同时其荧光性能不受温度和溶剂的影响。5.合成了一种基于ESIPT原理的比率型荧光探针,探针可对亚硫酸钠进行定量和定性检测。当探针溶液中加入亚硫酸钠后,探针的荧光光谱可以红移95nm。利用4-羟基萘酰亚胺的分子内电荷转移(ICT)特性,通过Cu2+催化探针酯基水解,设计合成了一种新型的检测Cu2+的荧光比率型探针。该探针对Cu2+的检测具有专一性且响应迅速。此外,探针可用于细胞内Cu2+的荧光比率成像。更多还原

【Abstract】 Abstract:Organic fluorescent dyes have been widely used for labeling of proteins, nucleic acids, lipids, carbohydrates, toxins, hormones and other biological molecules. More than85%of fluorophores are "Donor-acceptor" fluorescent dyes, having one or two donors and an accepter. However, the fluorescent quantum yield (0) of most fluorescent dyes is far below100%, which is mainly ascribed to the formation of the twisted intermolecular charge transfer at excited state (TICT theory). However, the TICT theory can not make a full explanation to the molecular structures of a variety of fluorescent dyes and is challenged to some extent. Furthermore, many aspects influencing the TICT mechanism need to be improved, such as the volume effect of amino donors, acceptor and the existence of two donors. Therefore, it is of great significance to further investigate the TICT mechanism, which is dedicated to the design of improved fluorescent dyes with excellent spectral properties and high quantum efficiency.Rhodamine dyes, a typical kinds of donor-acceptor fluorophores, exhibit good photophysical and photochemical properties. In this thesis, a series of Rhodamines having different acceptor or donors were synthesized and their photophyical photochemical properties were investigated. The relationship between the structures and optical properties in Rhodamines is dicussed. The discovery in this study can contribute to the TICT theory, be applied to many kinds of donor-acceptor fluorescent dyes, and useful to develop more efficient fluorescent dyes.The main contents are as follows:1. Seven novel symmetrical and unsymmetrical Rhodamine fluorescent dyes, having rigid/flexible alkyl and different electronegativities amino groups, were synthesized and studied by UV-vis, fluorescence spectra. The fluorescent quantum yield and lifetimes of the obtained Rhodamines were measured in different solvent at different temperatures. The results indicate that the rigidity of the donors and amino groups can effectively prevent the formation of TICT state and increase fluorescence lifetime. In TICT state, positive chares are mainly located on the two amino groups, and the one with better electron donating ability can sustain more positive charge. For unsymmetrical Rhodamines, there is a close relationship between lifetime and the rigid-flexible characteristics of stronger electron donationg amino group. The rigidity can prevent the TICT formation and make the dye higly fluorescent, whereas the flexibility can favor the TICT formation and decrease the fluorescence lifetime of Rhodamines.2. Using naphthalene sulfonic anhydride as raw material, seven naphthalenesulfonic acid Rhodamine fluorescent dyes have been successfully synthesized. The UV-vis absorbance spectra, fluorescence spectra, and the fluorescence lifetime under different solvents and different temperatures were determined. The difference in the fluorescence properties between the Rhodamine fluorescent dyes prepared using naphthalene sulfonic anhydride and benzene sulfonic anhydride as raw materials were discussed. Owing to the steric hindrance effect and the electronic effect of naphthalene sulfonic anhydride, it is not easy for the TICT excited state to form, which results in the improvement in the fluorescence properties. In comparison with the traditional Rhodamine fluorescent dyes in which benzene was used as the accepter, the seven Rhodamine fluorescent dyes synthesized exhibited a promoted fluorescence lifetime of38%.3. Nine rhodamines with different-sized dialkylamino groups were synthesized and their fluorescence lifetimes were measured in different solvents and temperatures. The results show that the volume of the amino groups can affect the formation of TICT state, thereby make the difference in the fluorescence lifetimes of fluorescent dyes. In the forming process of TICT excited state, Rhodamines with larger donor exhibit longer lifetimes than the smaller one, indicating the volume of the amino groups can affect the formation of TICT state. This result proved "volume effect in rotation activity" in TICT state, which is question by many researchers.4. Based on the TICT mechamism, Rhodamine dyes (AZESR, TMSR and PYRSR) with azetidine, dimethylamine and pyrrolidine as the electron donors were synthesized. Their absorption and emission spectra, Φ and fluorescence lifetimes were measured. The results showed that the AZESR possessed higher0and longer lifetime which were nearly independent of temperature and solvent.5. Based on ESIPT, a novel ratiometric fluorescent probe was synthesized. The probe is suitable for quantitative and qualitative detection of sulfite. With the addition of sodium sulfite, the fluorescence spectra exhibited a95-nm red-shift. By taking advantage of the ICT process inherent in4-hydroxynaphthalimide, a novel ratiometric fluorescence probe was designed. Owing to the hydrolysis of ester catalyzed by Cu2+, the probe showed good specificity and quick response to Cu2+. Most importantly, the probe has been successfully used for monitoring of Cu2+in living cells.更多还原