| With the development of society, environmental pollution resulting from chemical industry become so grave that all the researchers around the world try to find a way to solve this problem. However, designing and synthesizing the excellent and green catalyst is one important and effective approach. As we all know, homogenous catalysts has many merits compared with heterogenous ones, such as high activity and selectivity, but it is difficult to recover and recycle from the reaction system, which result in severe pollution and high cost. So, here, in order to overcome tedious separation processes, several catalysts such as interphase, ionic-tagged, fluorous-tagged, redox-switchable phase tagged, and some hererogenous catalyst, such as carbon and silicon materials-or polymer-supported catalysts have been developed.Polypyridine complexes of ruthenium (Ru(bpy)32+) is a classic visible light photocatalyst which can activate the transformation of organic molecules. This catalyst has received much attention in organic chemistry because it has mild conditions as a novel synthesizing method and it is a green catalyst. But Ru(bpy)32+is very expensive and it is hard to separate from the reaction system because of its good solubleness both in water and organic solvent, so we plan to recycle it by modification or immobilization to avoid environmental pollution.According the concept of green chemistry, to overcome the separation problem we choose the method of modification or immobilization of Ru(bpy)32+to reduce the consume of energy and high cost and aviod environmental pollution. As for the modification of Ru(bpy)32+, the nitrobenzospiropyran ((R/S)-SP) unit was chosen as the light-active group because it undergoes rapid and reversible photo transitions (with high quantum yield) between a colorless spiro (SP) state and a colored merocyanine (ME) state without generating photoproducts. So we want to employ the changeable solubleness of this compound after irradiation of UV light to recycle the catalyst. On other hand, for the immobilization of Ru(bpy)32+, reduce graphene oxide is choosed as a prefect supporter to build effective heterogeneous catalyst because of graphene-like material has many advantages to build effective heterogeneous catalyst such as high specific surface area, easy to disperse, good electrical conductivity and high stability. 1. I successfully get the the nitrobenzospiropyran ((R/S)-SP) unit-modified Ru(bpy)32+catalyst through organic synthesis. And, I successfully utilize it catalyze visible light photocatalyze dehalogenation reaction and get good activity and yield. However, because of the homogeneous reaction system during the process of reaction, it is still hard to get the ideal recovery from the homogeneous reaction system by the changeable solubleness after irradiation of UV light for the catalyst after modification. So,we have to seek another menthod, that is the one of immobilization, to recycle the catalyst.2. A novel visible light photocatalyst (Ru(bpy)3ClSO3-rGO) was successfully synthesized by chelating Ru(bpy)3Cl2complex with sodium benzenesulfonate functionalized reduced graphene oxide. This graphene-based Ru(bpy)3ClSO3-rGO catalyst exhibited high activity in photoredox dehalogenation reaction. And this novel visible light photoredox catalyst is stable and robust.3. In this part of work, I successfully immobilized Ru(bpy)3Cl2on mesoporous reduced graphene oxide. Then this catalyst is used in photocatalytic synthesis of2-arylpyridines via Hantzsch reaction and get good yield. |
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