【作者】 王晨；

【导师】 张逢星； 李珺；

【作者基本信息】 西北大学 ， 无机化学， 2009， 博士

【摘要】 自然界在漫长的发展演变过程中选择了卟啉作为植物体内光合作用的反应中心和动物体内携氧释氧的活性中心。这种由20个碳原子和4个氮原子组成的共轭大环以其独特的魅力不光丰富了自然界也丰富了人类化学研究领域,越来越多的目光被卟啉化合物所发出的光彩所吸引,卟啉化合物也在大家的关注中得到迅速的发展和应用。同时,在无机研究领域,自1972年Fujishima和Honda发现TiO₂电极光致分解水以来,TiO₂所表现出的种种独特性质,使之在众多研究领域中备受青睐。TiO₂众所周知的光催化活性、较高的稳定性、无毒及容易获得等优点,使之成为目前最有潜力的光催化材料。在可见光范围内有着强吸收的卟啉负载于具有良好光催化活性的TiO₂上,两者形成的“有机-无机”复合光敏催化材料在不断的实践与发展中为人们带来了更多的惊喜和希望。实验研究证实:这种“强-强”联合的新型材料能够利用清洁的太阳能对水溶液中的有机物分子进行有效的降解,使水中的总有机碳（TOC）含量降低,水质得到净化。但是,目前卟啉-TiO₂光敏材料作为一种污水光降解处理催化剂还尚在实验室研究阶段,距离工业化的实际应用还有很长路要走,人们对其中的许多细节问题还不清楚,特别是卟啉结构对光催化效果的影响以及光降解过程中的反应机理等。本课题紧随这一发展前沿,综合大量文献,筛选合成出具有特定结构的一系列卟啉配合物,将其负载于TiO₂表面,形成卟啉-TiO₂光敏催化剂,并在可见光照射条件下利用其对水溶液中对-硝基苯酚的不同降解效果,探讨了卟啉结构对催化剂催化效果的影响,总结了其影响的特点和规律,为今后卟啉-TiO₂光催化剂的进一步发展,提供了有益的借鉴和启示。本论文内容如下:1.在参考文献的基础上,合成了三种新的醛以及12种变化非常有规律的新型卟啉并对其进行了相应表征描述,总结了其结构和性质差异的关系。这十二种卟啉取代基数目分别为1、2、3、4个,其取代基位置分别在卟啉环中位取代苯环的邻、间、对位。变化有规律的取代基位置和数目,有利于发现并揭示影响敏化催化效率的规律。2.合成了相应卟啉的Cu（Ⅱ）、Zn（Ⅱ）、Fe（Ⅲ）、Co（Ⅱ）、Ni（Ⅱ）、Mn（Ⅲ）、Sn（Ⅳ）等金属卟啉共计51种,并进行了表征和分析。3.合成了相应卟啉或金属卟啉的TiO₂光敏催化剂并利用其对水溶液中的4-NP的光降解实验比较了它们的催化效果,发现配位金属在这一过程中起了极其重要的作用。另外,卟啉环上取代基的数目、位置、种类以及卟啉在TiO₂上面的负载量等因素都不同程度的影响了光催化效果。4.根据卟啉或金属卟啉的TiO₂光敏催化剂的光催化降解效果总结分析了造成这一结果的原因,为以后进一步研究合成高效光敏剂提供了思路和借鉴。5.总结参考其他文献及实验结果初步探讨了光降解过程中的反应机理。更多还原

【Abstract】 Nature has chosen porphyrin as the photosynthetic center for green plants and combine-release oxygen center for heme in their long process of development and evolution. The conjugated macrocycle,which is built by 20 carbon atoms and 4 nitrogen atoms,prospers the whole nature and the chemical research field due to its particular property,so it has attracted more and more attention.Meanwhile,in the inorganic research area,TiO₂ shows all kinds of unique properties and enjoys high popularity in the research field since Fujishima and Honda discovered that the TiO₂ electrode has the capacity of photo-induced decomposition of water in 1972.TiO₂ becomes one of the most potential photocatalytic materials at present due to its photocatalytic activity,high stability,innocuity and accessibility.As a kind of organic-inorganic composite photosensitive catalytic material, Porphyrins-TiO₂ brings more and more hope to people as it develops.This strong-strong united new-style material can degrade the organic pollution molecules efficiently in aqueous solutions,decrease the total organic carbon（TOC）,and purify water under solar light.However,Porphyrin-TiO₂ photocatalyst is still being tested in the laboratory for its photodegradation,and it will be a long time before industrial application.Some detailed problems in the process of photodegradation are still unknown,especially the influence of porphyrin structures on potocatalytic efficiency and the mechanism in this process.We synthesized some porphyrins and impregnated them onto the TiO₂ surface to produce a porphyrin-TiO₂ pohotocatalyst,to investigate the influence of porphyrin structures on potocatalytic efficiency by photo-degradation of 4-nitrophenol（4-NP） under visible light,and summarize the characteristics and rules of the influence and put forward some reflection and inspiration which can be used as reference for future research in this field.The main work in this paper is as follows:1.Three new aldehydes and twelve new porphyrins have been synthesized and characterized by various spectroscopic techniques.The relationship between the structure of porphyrins and their properties have been discussed and analyzed.The number of substitutions is one,two,three,and four respectively and the position of the substitutions is in the tetraphenylporphyrin’s ortho-,meta- and para- sites respectively.Changes in the terms of the position and number of substituents help to discover the efficiency of the porphyrins sensitization.2.Some metalloporphyrins have been synthesized and characterized,such as Cu（Ⅱ）, Zn（Ⅱ）,Fe（Ⅲ）,Co（Ⅱ）,Ni（Ⅱ）,Mn（Ⅲ）,Sn（Ⅳ）,etc.3.The photocatalytic activity of polycrystalline TiO₂ samples which are impregnated with porphyrins（metal free porphyrins and metalloporphyrins） as sensitizers have been investigated by carrying out the photo-degradation of 4-nitrophenol（4-NP） as a probe reaction in aqueous suspension and under visible light.Factors like the appropriate position and the number of substitutions,their spacer length,the type of the coordinated metal,and the amount of the porphyrin can influence the efficiency of TiO₂-porphyrins systems,but the coordination of metal is the key factor.4.We summarized the reasons for the different photocatalytic degradation effect of porphyrin-TiO₂,which will provide useful thought and reference for future researh5.At the same time,we summarized the reaction mechanism of the photo-degradation via some references and the experiment results.更多还原