Experimental and theoretical gas adsorption studies were performed in MPM-1-Cl and MPM-1-TIFSIX, two robust molecular porous materials (MPMs) with the empirical formula [Cu2(adenine)4Cl2]Cl2 and [Cu2(adenine)4(TiF6)2], respectively. Both MPMs consist of a hydrogen-bonding network that is self-assembled by dinuclear copper–adenine paddlewheel complexes. The difference between the two structures is simply the axial ligand. Experimental measurements revealed that MPM-1-TIFSIX displays higher CO2 uptake, isosteric heat of adsorption (Qst), and selectivity than MPM-1-Cl. These findings have been verified through molecular simulations. The zero-loading Qst for CO2 in MPM-1-TIFSIX is actually comparable to that for the top-performing metal–organic frameworks (MOFs). MPM-1-TIFSIX was also shown to exhibit high H2 uptake and Qst for H2 through experimental studies, which were subsequently supported by simulation. Modeling studies have also yielded insights into the adsorption sites in both MPMs. Only one principal adsorption site is present for CO2 and H2 in MPM-1-Cl and that is binding onto the Cl− counterions within the large channels. In contrast, three different adsorption sites were discovered for both adsorbates in MPM-1-TIFSIX: (1) between two TiF62– (TIFSIX) groups within a small passage connecting the large channels, (2) onto the TIFSIX ions lining the large channels, and (3) within the small channels.

Examining the gas adsorption properties in molecular porous materials based upon copper–adenine paddlewheel complexes

2019 Spring National Meeting

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