Pyrene-containing conjugated organic microporous polymers for photocatalytic hydrogen evolution from water

Abstract

Photoactive conjugated microporous polymers (CMPs) are emerging as porous materials capable of mediating the photocatalytic evolution of H₂ from water. In this study, we synthesized three pyrene-based CMPs (Py–F-CMP, Py–TPA-CMP, Py–TPE-CMP) through Sonogashira–Hagihara cross-couplings of 1,3,6,8-tetraethynylpyrene (Py–T, as a common monomer building block) with 2,7-dibromo-9H-fluorene (F–Br₂), tris(4-bromophenyl)amine (TPA–Br₃), and 1,1,2,2-tetrakis(4-bromophenyl)ethene (TPE–Br₄), respectively, in the presence of Pd(PPh₃)₄ in DMF/Et₃N. We then characterized the chemical structures, crystallinities, thermal stabilities, surface morphologies, and porosities of these three new CMPs. Brunauer–Emmett–Teller (BET) analyses and tests of photocatalytic H₂ production revealed that Py–TPA-CMP displayed the highest BET surface area (454 m² g⁻¹), highest total pore volume (0.28 cm³ g⁻¹), highest H₂ evolution rate (19 200 μmol h⁻¹ g⁻¹), and highest apparent quantum yield (15.3%) when compared with those of Py–F-CMP, Py–TPE-CMP, and other organic porous materials.