Abstract
Zn based Metal-Organic Framework (MOF), Zinc 1,4-benzenedicarboxylate (ZnBDC) has been synthesized and incorporated with ionic liquid (IL) 1-butyl-3 methylimidazolium bromide (BMIMBr) at optimum 50 wt% of IL. Interaction of BMIMBr in the micropores of ZnBDC-MOF is investigated by XPS, scanning EXAFS and inelastic neutron spectroscopy. Significant increase in binding energies of Zn spin-orbit peaks upon IL incorporation is observed from XPS spectra indicating motion of Br− anions of the IL BMIMBr towards the unsaturated Zn cluster of ZnBDC-MOF. The k-space periodicity as well as the local coordination geometry of Zn K-edge is investigated from the scanning EXAFS and XANES spectra. Asymmetric oscillation periodicity has been observed from the k-space scanning XANES spectra upon IL incorporation. Difference in peak positions of oxygen and zinc are observed from the R-space scanning EXAFS spectra suggesting change in coordination geometry due to dehydration of Zn2+ ion in the ZnBDC-MOF upon IL incorporation. Incorporation of IL in the pores of ZnBDC-MOF gives rise to increased scattering intensity in the Inelastic Neutron Scattering (INS) spectra, which is attributed to the displacement of IL ions in the MOF pores.
Inelastic neutron scattering study of binding of para-hydrogen in an ultra-microporous metal–organic framework