聚卟啉的制备及其在光氧化催化反应中的应用

Preparation of polyporphyrin and its application in photocatalysis

通过Sonogashira Hagihara偶联聚合制备了一系列具有多孔结构的网状交联聚卟啉光催化剂,设计了双溴双炔卟啉和四溴卟啉两种结构的卟啉单体,通过双溴双炔卟啉自聚得到多孔有机聚卟啉(PPOP-1),通过四溴卟啉与含双炔基的单体(1,7-辛二炔、对苯二炔、联苯二炔)共聚得到聚卟啉PPOP-2、PPOP-3和PPOP-4。通过SEM和物理吸附仪观测聚合物的表面形貌和表征孔结构。结果显示,4种聚合物均具有均匀的颗粒形态和微孔结构,孔径约1 nm,比表面积分别为38.484、12.494、10.880和19.858 m^(2)/g。以聚卟啉为异相光催化剂,通过可见光诱导二苄胺、缩硫酮、二苄基硫醚的有氧氧化证实了其对C—N和C—S键的氧化均具有优于单体催化剂的催化活性。PPOP-1(0.01 mmol)在可见光下催化二苄胺(0.1 mmol)的氧化反应,8 h后体系原料转化率和选择性均可达99%。经过4次循环催化后,PPOP-1仍保持较高的催化活性,原料转化率仍能达到99%。

A library of cross-linked polyporphyrins with porous and network structures were prepared via the Sonogashira Hagihara polymerization method to address the issues of the porphyrin monomers in separation, recycling and purification during the photocatalytic process. Two types of porphyrin monomers(dibromodiacetylenic porphyrin and tetrabromoporphyrin) were designed and the porphyrin-based porous organic polymer(PPOP-1) was obtained through self-polymerization of dibromodiacetylenic porphyrin. Three other polyporphyrins were obtained through the copolymerization of tetrabromoporphyrin and various linkers containing dialkynes. The surface morphology and pore structures of the polymers are characterized by scanning electron microscopy and physical adsorption. All four polymers had uniform ellipsoid morphology and microporous structures with the pore sizes about 1 nm. The specific surface areas are 38.484, 12.494, 10.880 and 19.858 m^(2)/g, respectively. The polyporphyrins were used as metal-free heterogeneous photocatalysts and the photocatalytic activity for C—N and C—S bonds were confirmed through the visible light-induced oxidation of dibenzylamine, bisaminothioketal and dibenzyl sulfide. The conversion rate of dibenzylamine(0.1 mmol) and selectivity of the target product after the PPOP-1(0.01 mmol) mediated catalyst under visible light for 8 h could reach 99%. The conversion rate of the raw materials could also maintain 99% after four cycles.