Why Porous Materials Have Selective Adsorptions: A Rational Aspect from Electrodynamics.

Gas storage/separation is a typical application of porous materials such as metal organic frameworks (MOFs). The adsorption/separation behavior results from the host-guest and/or guest-guest interaction and equilibration (host, porous material; guest, adsorbates). Although the driving forces for gas adsorption have been investigated, a detailed picture of interactions between gas molecules and MOFs has not clearly emerged. Herein, a new cobalt microporous MOF Co(tipb)(adc)(HO), which possesses a rare self-interpenetrated gra topology, has been prepared with both tipb and Hadc ligands (tipb = 1,3,5-tris(p-imidazolylphenyl)benzene, adc = 9,10-anthracenedicarboxylate). This MOF shows high stability and exceptional selective adsorption of CO over N, O, and CH. In particular, a theoretical assumption of a "regional dynamic electric field effect" is proposed to clarify the selective adsorption. Moreover, we suggest that the proposed effect may be one of the most important factors impacting gas separation and storage in porous materials.