Porphyrin-based 2D Covalent Organic Framework For Photocatalysis With TEMPO

Covalent organic frameworks(COFs)represent an emerging class of porous crystalline materials linked by covalent bonds.They can be divided into two-dimensional COFs and three-dimensional COFs.Two-dimensional COFs,in which the molecular building blocks are covalently connected to form a layered structure with aligned ?-columns,can particularly possess pre-organized pathways for facilitating the charge carrier transport.Accordingly,the photoexcited electron-hole recombination of 2D COFs can be inhibited to some extent,which will allow them to be used as heterogeneous photocatalysts.Based on the excellent photoelectric and redox properties of porphyrins,we construct a two-dimensional covalent framework,and explores the effect of cooperative photocatalysis on its catalytic performance.The main contents are as follows:1.Firstly,a two-dimensional covalent organic framework(Por-COF)was synthesized,and its structure and optical properties were investigated.The results showed that Por-COF has a structure of AA stacking that is conducive to electron transport.Moreover,Por-COF is suitable for photocatalysis,and its catalytic performance was proved by the selective oxidation of sulfides.2.In order to improve the catalytic performance of Por-COF,we used TEMPO as the redox mediator,and use the experiment of photocatalytic oxidation of sulfides to explore the cooperative effect between Por-COF and TEMPO.The results indicated that the cooperative photocatalysis can significantly improve the photocatalytic activity of Por-COF.Moreover,through quenching experiments and EPR spectrum,we proved the important role of superoxide radical in the reaction,and further elaborated the reaction mechanism of the cooperative photocatalysis in oxidation of sulfides.