【作者】 陈秀英；

【导师】 彭孝军；

【作者基本信息】 大连理工大学 ， 应用化学， 2006， 博士

【摘要】 菁染料由于摩尔消光系数大,吸收波长范围宽,光谱可调等优点,在现代生物分子荧光分析领域中应用十分广泛,近年来,菁染料作为光敏染料用于太阳能电池的开发也越来越受到学者们的关注。但染料存在的最大缺陷是光稳定性差,光照下易产生光漂白,不利于存储。因而研究染料光稳定性对染料在生物分析等领域具有重要的实际意义。 本文为了研究取代基效应对染料光分解速率的影响,设计合成了7种在3H吲哚环的N位具有不同供吸电取代基的系列近红外七甲川荧光菁染料。用500W的碘钨灯进行光照对比实验,通过紫外一可见吸收光谱最大值的实时跟踪,考察了不同取代基染料的光分解过程。实验结果发现:在3H吲哚环的N位引入供电子取代基,可以明显减小染料的光分解速率,提高了染料的光稳定性;引入吸电子取代基明显增大染料的光分解速率,降低染料的光稳定性;取代基供、吸电能力和染料的光稳定性具有很好的相关性。通过染料光分解实验定量得到了羧苄基取代染料和羧戊基取代染料光分解速率对比结果,对于引入羧戊基的染料,它的光分解速率是引入羧苄基染料光分解速率的2倍多。利用循环伏安实验对染料发生光分解过程的差别进行了解释,结果表明,给电子基取代染料,失去一个电子的氧化反应是可逆的,染料母体的破坏发生在染料失去两个电子后。吸电子基取代染料,失去一个电子的氧化反应是不可逆的,染料母体在失去一个电子后即被破坏。为了研究该类染料的光降解机理,将染料在甲醇及氘代甲醇中进行光照降解实验对比,结果表明:在氘代甲醇中的光降解速率常数与甲醇中光降解速率常数之比为6.2,远远小于单线态氧在氘代甲醇中的寿命与甲醇中寿命的比值20,因而染料的光降解路线不但按照单线态氧作用机理进行,同时也遵循超氧化物降解机理。根据文献报导的类似染料光降解路线及对其中三个染料光分解产物分别做HPLC-MS分析,推测了该类染料可能的光降解路线。 设计合成了5种新型含有羧苄基取代的高光稳定性的五甲川系列水溶性及非水溶性荧光菁染料。对染料的结构和纯化进行了改进及优化,采用正相硅胶柱色谱分离,水重结晶,获得了克级量的含有单个羧基的染料纯品,经过N—羟基琥珀酰亚胺活化后,有望用于核酸、蛋白质等生物分子的标记。对所合成的3H吲哚环N位含有对称及不对称更多还原

【Abstract】 Cyanine dyes have been widely used as fluorescence probes for biosystem in biomolecular analysis field duo to their large molar extinction coefficient, broad absorption spectra and wavelength tunability. Recently, more and more research has been focused on the application of cyanine dyes as photovoltaic material. However, the tendency to undergo photodegradation becomes the most common problem in irradiation, which are disadvantageous for long-term storage. Therefore the investigation on the photostability of cyanine dyes possesses the main significance in biomolecular analysis field.To study the effects of substituents on the rate of dyes photofading, 7 novel near-infiared heptamethine cyanine dyes with different electron-donating or electron-withdrawing substituents on N-position of 3H indolenine ring have been synthesized in this article. Photoreaction experiment was carried out irradiated with a 500W I-W lamp. Photofading behaviors of the dyes were investigated through determining the change of the maximal absorbance of the dyes. The results show that the dyes with electron-donating group on nitrogen atom of 3H indolenine ring perform the decreased photofading rate and the improved photostability compared with the dyes with electron-withdrawing group. The ability of the electron-donating or withdrawing bears the good correlation with the photostability of the dyes. The certain comparison of carboxylbenzyl and pentacarboxyl substituted dyes was obtained through photoreaction experiment And the photofading rate of the latter is double than mat of the former. Explanation was shown about the difference of the photofading process using cyclic voltammetry experiment The results show that the redox reaction of losing one electron for the electron-donating substituted dye is chemically reversible. The dye moiety was destroyed after losing two electrons. But the redox reaction of losing one electron for the electron-withdrawing substituted dye is chemically irreversible, and the dye moiety was destroyed after losing one electron. To investigate the mechanism of the photofading, Photodegradation experiments were carried out in methanol and deuterated methanol. The results show that the ratio of the rate constant in deuterated methanol compared with that in methanol is 62, which is far below 20, the ratio of the lifetime of singlet oxygen in deuterated methanol compared with that in methanol. Therefore the photodegradation route not only goes along with the singlet oxygen mechanism, but also follows the superoxide mechanism. Depending on the photofading route ofsimilar cyanine dye reported in previous literature and make HPLC-MS analysis to the residue of three cyanine dyes, the possible photorading route was deduced.Five novel water soluble and insoluble pentamethine cyanine dyes were synthesized with carboxylbenzyl group. The design of the structure and the purification are optimized. Gram level of purified dye with mono-carboxyl group is obtained through positive silica gel chromatogram and recrystallization from water, which exhibits the potential application as probe of oligonucleic acid and protein activated by the iV’-hydroxylsuccinimide. The photofading experiment was carried out among the pentamethine cyanine dyes with asymmetric and symmetric substituted groups on Apposition. The results show that the photostabilities of the asymmetric dyes is more excellent than that of symmetric dyes. The introducing of benzyl and ethyl groups on N-position enhances the stability of the dyes obviously. In addition, introducing of carboxyl group on N-position is not favorable to increasing the photostabilities of the dyes.Presently, the main problem of the cyanine dyes as sensitizers tor the DSSC is the low photoelectric conversion efficiency. So novel cyanine dyes are necessary to be synthesized. To investigate the effect of sensitizers on the photoelectron conversion efficiency, novel trimethine cyanine dye and squarylium dye with high photostability were synthesized and used as sensitizers for DSSC. The results show that Isc (2.76mA/cm2), IPCE (46%) and tj (1.7%) of TiC>2 nanocrystalline solar cell sensitized by squarylium dye perform preferable values than that of T1O2 nanocrystalline solar cell sensitized by trimethine cyanine dye when the TiC>2 nanostructured porous film was 6.5um thick and was sensitized for 6 hours and 4 hours respectively. Several reasons were considered to lead to the different photoelectric properties of the two T1Q2 electrodes sensitized by the two dyes. Firstly, spectrum range of squarylium dye shifts to the long wavelength region, which is favorable to absorb solar light Moreover, the lowest excited energy level of squarylium dye matches well to that of T1Q2 nanoparticle conductive band gap. And the photoisomerization is one of the major decay pathways for methine dyes, squarylium dye with methine chain substituted by squaric acid ring reduces cis-trans isomers. It is favorable to form ordered orientation on TiQ? surface so as to increase the electron injection efficiency obviously. Moreover, the J-aggregated dyes on TiO2 surface and the effects on the photoelectric properties of the electrodes were discussed.Different aggregation of cyanine dyes in DMF-water solvent were investigated and the effect of electrolyte, solid medium, concentration of the dyes were studied. The hydrophobic action is the driving force to aggregate. The molecular structure, solvents, solid interface are the main factors to lead to aggregate.更多还原