Lattice response of the porous coordination framework Zn(hba) to guest adsorption

Abstract

Analysis of in situ neutron powder diffraction data collected for the porous framework material Zn(hba) during gas adsorption reveals a two-stage response of the host lattice to increasing CO2 guest concentration, suggesting progressive occupation of multiple CO2 adsorption sites with different binding strengths. The response of the lattice to moderate CH4 guest concentrations is virtually indistinguishable from the response to CO2, demonstrating that the influence of host–guest interactions on the Zn(hba) framework is defined more strongly by the concentration than by the identity of the guests.

Insights into Selective Gas Sorbent Functionality Gained by Using Time‐Resolved Neutron Diffraction

“…Even so, the magnitude of the effect of approximately 0.5 CD 4 on thermal expansion is still considerably smaller than that expected for a 0.5 CO 2 dose . Distinctions between the framework responses to different guest species are observed commonly in MOFs owing to differences in host–guest interaction strength, which are often exploited to separate CO 2 from CH 4 or elemental gases, and the absence of any guest dependence in the structural responses of certain MOFs has been considered indicative of purely kinetic separation mechanisms such as those based on steric limitation . However, the lack of CD 4 guests at Site 2 introduces the possibility that the different lattice behavior arises from the unequal contributions of guests at different binding sites to the [Cu 3 (cdm) 4 ] lattice expansion characteristics, as mentioned in the previous section.…”