One-pot approach to Pd-loaded porous polymers with properties tunable by the oxidation state of the phosphorus core

Abstract

Two novel Pd-loaded heteroatom-linked microporous polymers Pd@NP and Pd@NPO were effectively synthesized by one-pot Pd-catalyzed Heck coupling reactions of tris(4-vinylphenyl)amine with tris(4-bromophenyl)phosphine and tris(4-bromophenyl)phosphine oxide, respectively. The Pd atoms loaded into the networks of the resulting porous polymers originated from the Pd-catalyst used in the polymerization, which was achieved under moderate reaction conditions. Besides the nitrogen atoms, the trivalent phosphorus atoms bearing one lone pair of electrons and the pentavalent phosphorus atoms of the phosphoryl groups were used as the linkers for the formation of the frameworks of the porous polymers Pd@NP and Pd@NPO, respectively. The phosphorus atoms with different oxidation states in the networks caused a dramatic variation in the physical and catalytic properties of the as-prepared porous polymers. Pd@NP and Pd@NPO exhibit surface areas of 381 m² g⁻¹ and 684 m² g⁻¹, respectively. Both Pd-loaded porous polymers enable efficient Suzuki–Miyaura coupling reactions featuring short reaction times and good yields, with the catalysts being highly stable and easy to recycle. The catalytic activity of Pd@NPO is higher than that of Pd@NP.