One-pot Synthesis of Pd/Azo-polymer as an Efficient Catalyst for 4-Nitrophenol Reduction and Suzuki-Miyaura Coupling Reaction.

The porous polymer matrix with good stability and confined microenvironment is considered as ideal support to stabilize isolated metal centers for catalysis. Herein, we report a "one-pot" method to prepare a kind of palladium complexed with azo porous organic polymer nanospheres (Pd-azo-POPs). The method combines the synthesis of azo-POPs with the reduction of the Pd ion, where azo serves as an anchoring group to limit the growth of Pd. The unique structure is conductive to the formation of a uniform active center and provides improved electron transfer. Pd-azo-POPs-80 exhibits a high catalytic activity and cycling stability both in 4-nitrophenol reduction and Suzuki-Miyaura coupling. The knor for the 4-nitrophenol reduction was 174.7 min-1  mM-1 and the conversion remains above 90% after 6 cycles. Meanwhile, the yield was still up to 94.5% after 5 cycles for the Suzuki-Miyaura coupling reaction of benzene derivatives with I/Br under mild conditions.