Journal article Open Access
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, we expand the toolbox available to polymer and materials chemists by one additional nonmetal, phosphorus. Starting with a building block that contains a λ5-phosphinine (C5P) moiety, we evaluate a number of polymerisation protocols, finally obtaining a π-conjugated, covalent phosphinine-based framework (CPF-1) via Suzuki-Miyaura coupling. CPF-1 is a weakly porous polymer glass (72.4 m2 g-1 N2 BET at 77 K) with green fluorescence (λmax 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 μmol h-1 g-1. Our 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 that might spark future interest in their applications in light-emitting devices and heterogeneous catalysis.