Unraveling the molecular details of the “gate opening” phenomenon in ZIF-8 with X-ray absorption spectroscopy

DOI: 10.1021/acs.jpcc.2c00373

Authors: Roberto Boada (Diamond Light Source) , Jesus Chaboy (Diamond Light Source) , Shusaku Hayama (Diamond Light Source) , Luke Keenan (Diamond Light Source) , Adam A. Freeman (Diamond Light Source) , Monica Amboage (Diamond Light Source) , Sofia Diaz-Moreno (Diamond Light Source)
Co-authored by industrial partner: No

Type: Journal Paper
Journal: The Journal Of Physical Chemistry C

State: Published (Approved)
Published: March 2022
Diamond Proposal Number(s): 9970

Abstract: The local structural changes associated with the ZIF-8 framework flexibility upon nitrogen gas adsorption have been studied by in situ X-ray absorption spectroscopy (XAS) and high-energy-resolution fluorescence-detected X-ray absorption near-edge structure (HERFD-XANES) spectroscopy. Different thermodynamic conditions (isobar and isotherm) have been used to explore the so-called “gate opening” transition in which the hexagonal pore windows of the sodalite cage open, increasing the accessible volume for gas adsorption. To elucidate the source of the spectral changes in the XANES region of the absorption spectra observed along the gas adsorption and through the transition from the closed to the open pore configuration, ab initio calculations have been performed. Our results demonstrate that the transition from the closed to the open pore configurations involves not only the rotation of the MeIM ligand but also a further bend of the Me group away from the plane defined by the IM ring. Additionally, the contribution of the N2 molecules adsorbed in the center of the 4-ring window has been included in the scattering model to fully reproduce the main features of the X-ray absorption spectra in the open pore configuration.

Journal Keywords: X-ray absorption near edge spectroscopy; Ligands; Metal organic frameworks; Extended X-ray absorption fine structure; Surface chemistry

Subject Areas: Materials, Chemistry


Instruments: I20-Scanning-X-ray spectroscopy (XAS/XES)

Added On: 30/03/2022 08:58

Documents:
acs.jpcc.2c00373.pdf

Discipline Tags:

Zeolites Physical Chemistry Chemistry Materials Science Metal-Organic Frameworks Metallurgy Organometallic Chemistry

Technical Tags:

Spectroscopy X-ray Absorption Spectroscopy (XAS) High Energy Resolution Fluorescence Detected XAS (HERFD-XAS)