【作者】 王宏；

【导师】 蔡伟民；

【作者基本信息】 上海交通大学 ， 环境工程， 2009， 博士

【摘要】 光敏化合物在环境工程上有着重要的应用潜力,在污水处理、环境友好型农用化学品和水华控制上都能发挥重要的作用。由于植物源光敏化合物不稳定、含量低、效果差等一系列固有的缺陷,本论文着重研究了一类化学合成的光敏化合物——呫吨类化合物的光敏生物活性、光降解及开发利用。呫吨类化合物已经应用于实际生产和生活中，但对其光敏生物活性和光降解机理的研究还很不系统和充分。同时,文献对光敏化合物的活性测试的方法和结论也千差万别。通过前人的研究无法全面评价该类化合物的光敏活性的构效关系以及其生物安全性,这对于全面开发呫吨类化合物形成了很大的局限性虼耍韭畚慕?研究这类化合物的分子结构规律,生物活性规律和光降解规律,为实际应用提供理论基础。同时,本论文还研究了呫吨类化合物对铜绿微囊藻的生长以及叶绿素a含量的影响,探讨了其应用为环境友好型灭藻剂的可能性。研究成果主要如下: 1.呫吨类化合物的物化性质的变化规律为：最大吸收峰在490 nm到539 nm之间,随着取代卤原子的相对原子质量的增加或者卤原子数的增加,最大吸收峰朝长波方向移动;供试呫吨类化合物亲脂性从大到小依次为FlI2>FlBr2>Na2FlBr4Cl4>Na2FlI4>Na2FlBr4>Na2Fl,其中亲脂性最大的FlI2的正辛醇-水分配能力是Na2Fl的正辛醇-水分配能力的约32倍;供试呫吨类化合物的相对单线态氧产率从大到小依次为Na2FlBr4Cl4(1)>Na2FlI4(0.92)>Na2FlBr4(0.81)>FlI2(0.69)>FlBr2(0.67)>Na2F(0.02)。2.呫吨类化合物的生物活性的变化规律为：未经光照的条件下，呫吨类化合物的对同种待测微生物的固有生物活性基本相同,说明固有毒性可能主要决定于化合物分子的母核结构,其卤素取代基团对其影响较小;经实验光源照射下,所测MLC值明显低于未经光照条件下的值,表明呫吨类化合物对三种微生物的光敏活性明显强于对其相应的固有活性;呫吨类化合物对革兰氏阳性菌能发挥较大的光敏活性。由物化性质和生物活性的测试结果可知:光敏生物活性的测试与单线态氧的测试结果保持了高度的一致性,用单线态氧的产率这个指标来评价对微生物的光敏活性比用亲脂亲水性指标更为有效。协同作用的测试结果显示:Na2Fl的对其他五种呫吨类化合物表现出了明显的协同促进作用；当亲脂性化合物与亲水性化合物共同作用时,协同作用效果也十分明显。3.呫吨类化合物的光降解规律为：在水溶液中的光降解是假一级动力学化学反应,半衰期在5小时到7小时之间,属于同一个数量级。脂溶性高的化合物比水溶性高的化合物半衰期长,较难降解。随着反应时间的增加,化合物最大吸收峰处的光吸收值逐渐减小,但没有明显的新的吸收峰出现,这说明在反应过程中部分光敏化合物发生完全降解,成为小分子化合物或离子;六种呫吨类化合物在硅胶基质的光降解也符合假一级动力学化学反应的规律,半衰期在1小时到2小时之间。在相同的实验条件下,同种呫吨类化合物在水溶液中降解的半衰期均为其在硅胶基质上降解的半衰期的4倍左右。4.对光降解中间产物和终产物的研究结果显示:光敏试验中C20H6O5Br4Na2能迅速而完全降解为小分子化合物CO2、HBr、NaBr和H2O等;以酵母菌为测试菌,证实了在降解过程中,中间产物和终产物的光敏生物活性也在不断降低。实验证实,呫吨类化合物在自然条件下能在发挥光敏生物活性的同时迅速降解为小分子化合物,残留量少,同时,其降解中间产物和终产物的光敏生物活性也迅速降低,对环境的潜在风险很小。5.呫吨类化合物对铜绿微囊藻的测试结果显示：供试样品中对供试藻种活性最强的是Na2FlBr4Cl4,其MLC值为在光照条件下为40μM,在无光条件下为90μM;通过Na2FlBr4Cl4对铜绿微囊藻的生长量以及叶绿素a含量的影响的研究发现,在较低的浓度范围内,呫吨类化合物对铜绿微囊藻的生长没有太大影响，而在中高的浓度范围内,则能产生显著的抑制效应。由于呫吨类化合物能在自然环境中迅速降解，残留度低,显示了一定的作为环境友好型灭藻剂开发的潜能。更多还原

【Abstract】 Photosensitizers have great potentials in environmental engineering, such as wastewater treatment, environment friendly agrochemicals and algae bloom control. Because vegetation sourced photosensitizers are unstable, low concentration in plant and insignificant effect, we put our emphasis on a kind of chemical photosensitizers - xanthene.Xanthene chemicals have been used in production and life. However, the research of their photoactivity and photodegradation is not systemic and adequate. At the same time, the methods and results differ in thousands ways from different research. This restricts the full application of this kind of chemical. Thus, this study focuses on the rules of molecular structure, photo bioactivity and photodegradation, which will provide the theoretics basis for application. We also research on the effect of xanthene chemicals to the growth of Microcystis aeruginosa and the content of chlorophyll a, and discuss on the possibility for the xanthene chemicals to be developed as algaecide. The results of experiments are as per below.1. The rules of physiochemical characters are: In vitro physicochemical tests showed that the max absorption wavelength of the photosensitizers is between 490 to 539 nm, which coincides with the spectral output of the sunlight; The sequence of lipophilicity of xanthene derivatives is: FlI2(1.21)>FlBr2(1.01)>Na2FlBr4Cl4(-0.21)>Na2FlI4(-0.24)>Na2FlBr4(-0.25)>Na2Fl(-0.28); Each of the xanthene derivatives was able to photosensitize the production of singlet oxygen, in the order of Na2FlBr4Cl4(1)>Na2FlI4(0.92) > Na2FlBr4(0.81) > FlI2(0.69) > FlBr2(0.67) > Na2F(0.02). With the increasing number of halogen substituents, the singlet oxygen yields increased and the phototoxic activity increased too.2. The rules of photo bioactivities are: Without illumination, the tested xanthene derivatives showed almost the same level of inherent toxicity to the same organism, which showed the inherent toxicity of xanthene derivatives were primarily dependent on the structure of parent molecule. Upon illumination, the photosensitizers showed obvious phototoxicity to all organisms. The xanthene derivatives showed stronger phototoxicity to Gram-positive bacteria. With the increasing number of halogen substituents, the singlet oxygen yields increased and the phototoxic activity increased too. There was no obvious correlation between relative lipophilicity and activity in the current study. Na2Fl showed obvious synergetic action to other xanthene derivatives; it also show obvious synergetic action as combined lipophilic xanthene chemical and hydrophilic xanthene chemical. The synergetic action for xanthene derivatives is more effective to Escherichia coli that the other two microorganisms.3. The rules of photodegradation are: The degradation of xanthene derivatives in solution and on the surface of silica TLC plates is pseudo first-order kinetic reaction. The half life of xanthene derivatives in water is between 5 hours to 7 hours, and on the surface of silica TLC plates is between 1 hour to 2 hours. The half life of lipophilic xanthene derivatives is longer than that of hydrophilic xanthene derivatives.4. The research of the intermediate products and final products during photodegradation shows: The complete degradation of photosensitizers to CO2 is of great environmental significance. During photodegradation test, the TOC content of C20H6O5Br4Na2 decreased around 50% during the 8 hour irradiation period. Irradiation also led to a gradual increase in the number of microorganisms that could survive. This means, when subject to light, the photosensitizer solutions degraded rapidly and the phototoxicity of the residues disappeared quickly. Actually, the energy density in the natural environment is much stronger than that in the experiment. Thus, the photosensitizers are expected to degrade more rapidly in the environment.5. Na2Fl shows no obvious algaecidal activity with or without illumination, however, the other five xanthene derivatives shows approximately similar inherent toxicity and phototoxicity. Na2FlBr4Cl4 shows the maximum algaecidal activity, and the MLC value is 40μM with illumination and 90μM without illumination. From the research on the Na2FlBr4Cl4 against the growth of algae and the content of chlorophyll a, we obtains that xanthene derivatives have little effect on the growth of algae at low concentration and can restrain the growth of algae at middle and high concentration. Because xanthene derivatives can degrade rapidly in the natural environment, thus, they can be developed as algaecide. The mechanism to kill the algae needs further research.更多还原