Preparation And Properties Of Porphyrin-based Conjugated Microporous Polymer

Porphyrin have large conjugated systems,good visible light absorption properties and structural modifiable properties.Therefore,porphyrin derivatives as a homogeneous photocatalyst has been widely applied to degrade aromatic organic pollutants in water.However,porphyrins are easy to aggregate into dimers,which greatly reduces their photocatalytic efficiency.In addition,as small organic molecules,it is difficult to recycle from solution.Incorporating porphyrin as a structural unit into conjugated microporous polymers（CMPs）to prepare heterogeneous photocatalysts,not only solve the problem of porphyrin aggregation,but are also easy to recycle and reuse without causing secondary pollution to the environment.At the same time,the extendedπ-conjugated system effectively increases the photocatalytic efficiency.In this study,5,10,15,20-tetra（4-carboxyphenyl）porphyrin（TCPP）and 5,10,15,20-tetra（4-aminophenyl）porphyrin（TAPP）as structural unit,3,3’-diamino-4,4’-di-hydroxybiphenyl（DADHBP）and 1,10-phenanthroline-5,6-dione（PD）as bridging agent,two conjugated microporous polymers（TCPP-DADHBP-CMP and TAPP-PD-CMP）were synthesized via polycondensation reaction and Schiff base reaction,respectively.A series of conjugated microporous polymers with metal coordination（Cu TCPP-DADHBP-CMP,Ni TCPP-DADHBP-CMP,Cu TAPP-PD-CMP,Ni TAPP-PD-CMP）were derivatized.The structures and physical properties of CMPs were characterized by FT-IR,¹³C NMR,UV-Vis,XRD,TGA and Nitrogen adsorption and desorption.TCPP-DADHBP-CMP,Cu TCPP-DADHBP-CMP and Ni TCPP-DADHBP-CMP using DADHBP as bridging agent were used as photocatalysts to carry out photocatalytic performance experiments.Among them,Cu TCPP-DADHBP-CMP has the highest photocatalytic efficiency,under visible light irradiation,the degradation rate of Rhodamine B can reach 96%after 180 min.Three cycles of experiments were carried out,Cu TCPP-DADHBP-CMP degradation rate of rhodamine B still reached 95%.Isopropanol was used as the trapping agent for OH·,p-benzoquinone was the trapping agent for·O2^-,and 1,3-diphenylisobenzofuran was used as the trapping agent for ¹O2.It is proved that the main active substances in the photocatalytic process of this kind of photocatalyst are OH·and ¹O2.TAPP-PD-CMP,Cu TAPP-PD-CMP,Ni TAPP-PD-CMP with PD as the bridging agent were used as photocatalysts to carry out photocatalytic performance experiments.Among them,Ni TAPP-PD-CMP has the highest photocatalytic efficiency,under visible light irradiation,the degradation rate of Rhodamine B can reach 98%after 180min.Three cycles of experiments were carried out,Ni TAPP-PD-CMP degradation rate of rhodamine B still reached 92%.Using the method of the previous system and under the same experimental conditions,it is proved that the main active substance in the photocatalytic process of this type of photocatalyst is ¹O2.