多级孔芳香骨架材料的合成及固载硫脲催化剂的研究

合成了一种多级孔芳香骨架材料(PAF-70); 使用由氨基修饰过的单体, 应用该合成策略得到了同样具有窄分布介孔的含有氨基活性位点的PAF材料, 并通过硫脲单体与其氨基活性位点的反应, 将硫脲基团引入PAF-70材料中, 获得了含有硫脲催化位点的材料(PAF-70-thiourea). 氮气吸附-脱附测试结果显示, PAF-70存在孔径分布较窄的介孔, 介孔孔径为3.8 nm, 与模拟计算值(约3.7 nm)吻合. 热重分析结果表明, PAF-70具有很高的热稳定性. PAF-70在大多数溶剂中可以稳定存在, 具有良好的化学稳定性. 将PAF-70-thiourea作为催化剂, 应用在N-溴代琥珀酰亚胺(NBS)氧化醇类的反应中, 其表现出较高的催化活性、 较高的稳定性和广泛的底物适用性. 与含有相同硫脲催化位点的金属有机框架(MOF)材料(IRMOF-3-thiourea)作为催化剂对比, 进一步证实PAFs材料非常适合作为催化有机反应的固载平台.

Synthesis of Hierarchical Porous Aromatic Frameworks for Immobilization of Thiourea Catalyst

A hierarchical porous aromatic framework（PAF-70） was synthesized via a new synthetic strategy. Nitrogen adsorption-desorption isotherms showed that PAF-70 had mesoporous structure with narrowly distributed pore size. The pore width of PAF-70 was 3.8 nm， which agreed well with the simulation value（ca. 3.7 nm）. Thermogravimetric analysis displayed good thermal stability of PAF-70. Furthermore， PAF-70 could not be dissolved or decomposed in almost all common solvents， which demonstrated its high chemical stability. Noteworthily， the amine group in the monomer had no negative influence on the synthetic strategy， and the amine-tagged PAF with mesopores could be obtained by the same synthetic strategy. Then using a post-synthesis modification strategy， the thiourea unit was easily introduced into the pores of PAF-70 to synthesize PAF-70-thiourea. The catalytic performance of PAF-70- thiourea was further tested using a series of alcohols in the catalysis of N-bromosuccinimide（NBS）-mediated oxidation of alcohols. In the current catalyst system PAF-70-thiourea showed high catalytic activity， high stability as well as broad substrate suitability. In comparison with the thiourea-containing MOF（IRMOF-3-thiourea） in the same catalyst system， the experimental results further demonstrated that PAFs are more suitable platforms for immobilization of catalyst for organocatalysis.