A π-conjugated, covalent phosphinine framework.

Structural modularity of polymer frameworks is a key advantage of covalent organic polymers, however, only C, N, O, Si, and S have found their way into their building blocks so far. Here, the toolbox available to polymer and materials chemists is expanded by one additional nonmetal, phosphorus. Starting with a building block that contains a lambda(5)-phosphinine (C5P) moiety, a number of polymerization protocols are evaluated, finally obtaining a pi-conjugated, covalent phosphinine-based framework (CPF-1) through Suzuki-Miyaura coupling. CPF-1 is a weakly porous polymer glass (72.4 m(2) g(-1) BET at 77 K) with green fluorescence (lambda(max)=546 nm) and extremely high thermal stability. The polymer catalyzes hydrogen evolution from water under UV and visible light irradiation without the need for additional co-catalyst at a rate of 33.3 mu mol h(-1) g(-1). These results demonstrate for the first time the incorporation of the phosphinine motif into a complex polymer framework. Phosphinine-based frameworks show promising electronic and optical properties, which might spark future interest in their applications in light-emitting devices and heterogeneous catalysis.