Combined Solid-State NMR and Computational Approach for Probing the CO2 Binding Sites in a Porous-Organic Polymer

We report on utilization of 1D and 2D 13C cross-polarization magic angle spinning (CPMAS) and MAS solid-state NMR spectroscopy in probing the binding sites and dynamical processes of 13C-enriched CO2 inside the pores of a pyridine-containing porous organic polymer (POP). Our findings from the spectroscopic measurements conducted on the evacuated sample and on the sample dosed with 800 mbar 13CO2 indicated preferential adsorption of the CO2 molecules at the vicinity of the basic binding sites within the POP, the pyridine rings. We further demonstrate the results of a computational study for probing the most favorable binding sites of CO2 inside a geometrically optimized model of the polymer in an attempt to better rationalize the experimental findings from 13C solid-state NMR investigations. Because of the amorphous nature of the studied POP, also being observed for a large number of emerging microporous solids, this combined approach can prove useful and versatile toward drawing a detailed picture of the gas–solid interactions, aiming for enhanced designs for futuristic materials toward CO2 capture and sequestration.