Multifunctional porous organic polymers: tuning of porosity, CO2 and H2 storage and visible-light-driven photocatalysis.

A series of porous organic polymers (POPs) were fabricated based on the boron dipyrromethene (BODIPY) core. The variation of the substituents in the BODIPY core and the fine tuning of the Sonogashira polycondenzation reaction with 1,3,5-triethynylbenzene led to the formation of POPs with a wide range of surface area and porosity. A tenfold increase in surface area from 73 m2g-1 in BDT1a polymer to 1010 m2g-1 in BDT3 was obtained. Simultaneously, the porosity was changed from mesoporous to ultramicroporous. The surface area of BDT3 turned out to be the highest reported so far for BODIPY based POPs. Molecular dynamics simulation coupled with Grand Canonical Monte Carlo simulations revealed the effect of substituents alkyl groups and rigidity of the core structures on the surface properties of the POPs. Detailed gas adsorption studies of the polymers revealed a high uptake of CO2 and H¬2. The highest uptake capacity of 16.5 wt. % for CO2 at 273 K and 2.2 wt.% for H¬2 at 77 K was observed for BDT3 at 1 bar pressure. Isosteric heat of adsorption (Qst) of BDT3 for CO2 was found to be as high as 30.6 kJ mol-1. Electron paramagnetic resonance studies revealed the generation of singlet oxygen upon photoexcitation of these polymers. The BODIPY based POPs turned out to be excellent catalysts for visible-light-driven photooxidation of thioanisole. The present study establishes BODIPY based POPs as a new class of multifunctional materials.