Design And Synthesis Of Perylenequinone And Anthraquinone Photosensitizers And Applications In Photocatalytic Reactions

Visible light has attracted great attention as a green and sustainable energy.Visible light photocatalysis uses a photocatalyst as the carrier to convert light energy into chemical energy to drive organic reactions.Photocatalyst is the core of photocatalysis.Compared with the expensive and toxic metal photocatalysts,organic photocatalysts are cheap,easy to obtain,and environmentally friendly,and are currently a hot spot in photocatalysis research.Therefore,it is of great significance to develop organic photocatalysts with novel structures,high photocatalytic activity and strong photostability.In view of the good photosensitivity of quinones,in this thesis,the perylene quinone compound cercosporin and the anthraquinone derivative aloe-emodin were used as the photocatalysts to realize the synthesis of a series of drug molecular skeletons with important biological activities.The details are as follows:1.The development of new organic photocatalyst HARCP with cercosporin as the parentOn the basis of our previous research on the photocatalysis of cercosporin,a new photocatalyst HARCP was prepared by structural modification of cercosporin through reduction and acylation reactions.It was confirmed with UV absorption spectra that it has good light absorption ability in the UV-visible region.The improvement of its electron transfer ability was confirmed with the study of fluorescence properties.Its redox potential was confirmed with electrochemical properties studies and demonstrated the enhancement of photocatalytic single-electron transfer capability of HARCP.The triplet energy was also calculated with phosphorescence emission spectra and demonstrated the improvement in energy transfer capability of HARCP.2.The arylation of aromatic hydrocarbons and the construction of Csp²-Csp² bond with the enhancement of single electron transfer capability of HARCP photocatalysisUnder the irradiation of visible light,the photocatalytic single electron transfer ability of HARCP was applied to realize the photocatalytic coupling of aryl halides and（hetero）aromatic hydrocarbons,and a series of Csp²-Csp² bonds were successfully constructed.By optimizing the factors such as the type of photocatalysts,the type of bases,the equivalent of bases,light sources and solvents,the optimal reaction conditions were confirmed.Under these conditions,the universality of the substrates was studied,and the extension of aryl halogenates and（hetero）aromatics was carried out.The reaction mechanism was also speculated.After irradiation,HARCP jumped to the excited state and electron transfer occured with DIPEA to form HARCP^·-,and then HARCP^·-reduced the aryl halide to generate aryl radicals,and finally the aryl radicals were added to aromatic（hybrid）hydrocarbons to generate the coupling products.3.The arylation of the sulfonamide and the construction of the Csp²-N bond with the improvement of the photocatalytic energy transfer capability of HARCPUnder visible light irradiation,a series of N-aryl sulfonamides with potential biological activities were synthesized by the combination of energy transfer of HARCP and d metal nickel catalysis.By optimizing the factors such as nickel salts,ligands,alkalis and solvents,the optimal reaction conditions were confirmed.Under the optimal conditions,the substrate range and functional group tolerance were studied.The reaction mechanism was also studied.Ni^II-arylamino complex was formed by coordination,oxidation addition,ligand exchange and deprotonation,and then energy transfer occured between HARCP excited state and Ni^II-arylamino complex to form Ni^II-arylamino complex excited state,and N-arylsulfonamide was formed by reduction elimination.4.Selective photoxidation of thioether to sulfoxide with aloe-emodin as the photocatalystIn view of the widespread existence and important biological activity of sulfoxide in the drug structure,aloe-emodin was used as a photocatalyst to realize the selectivity of sulfoxide by taking advantage of the natural photosensitivity of aloe-emodin,its wide source,cheap and easy availability,and green safety.Through the optimization of the reaction conditions,the best photocatalytic conditions of aloe-emodin were confirmed.The range of substrates and the tolerance of functional groups were studied under the optimum conditions.The photoxidation mechanism of aloe emodin was studied through a series of controlled experiments.