Fabrication of Flexible Co-salen Integrated Polymers for Hydration of Epoxides and Alkynes via Cooperative Activation

Most cross-linked polymers with integrated active sites in the network have poor flexibility, which inhibits their applications in catalysis involving a cooperative activation pathway. Herein, a flexible organic polymer with high concentration of salen ligand in the network (SOP) was successfully synthesized by the reaction of meso-1,2-diphenylethylenediamine and 1,3,5-tris(3'-tert-butyl-4'-hydroxy-5'-formylphenyl)benzene. The post-synthesis coordination with Co-II followed by further oxidation results in the formation of SOP-Co-OTs. The large amounts uptake of benzene of SOP and variation of the BET surface area after coordination with different metal cations confirmed the network flexibility. Consequently, SOP-Co-OTs could efficiently catalyze the epoxides hydration to afford turnover frequency up to 2400 h(-1) via cooperative activation. Furthermore, SOP-Co-OTs works cooperatively with Amberlyst-15 in the hydration of phenylacetylene to afford higher yield than homogeneous Co-salen. Our primary results suggest the potential applications of flexible polymer catalysts in reactions involving cooperative activation pathway.