Synthesis and fine-tuning the pore properties of a thiophene based porous organic framework by post-oxidation treatment

Porous organic frameworks (POFs) are an important class of materials, which have attracted great interests in recent years. The post modification of porous organic frameworks provides an efficient way to fine tune the properties of POFs for specific applications. However, most of the post functionalization methods need harsh reaction conditions and specific reagents and lead to a notable pore width decrease, which hinder the pore accessibility. Herein, we designed and synthesized a thiophene based POF with high surface area and stability. A straightforward post-oxidation of thiophene based POFs by meta-chloroperbenzoic acid introduced sulfone groups as hydrogen bonding sites in the channel with a less effected pore width in a controllable manner. The hydrogen bond acceptor sulfone groups could promote the adsorption of ammonia and enhance the proton conductivity of phosphoric acid or imidazole infiltrated POFs. The proton conductivity of phosphoric acid doped oxidized thiophene based POFs is over 10^-3 S cm^-1 at 120 °C under anhydrous conditions, which could be a promising candidate for fuel cells.