Open Sesame! Simulation of the Adsorption Induced Phase Transformation Mechanism of MOF Nanocrystallites
Year: 2026
Type: preprint
Abstract: One of the most compelling features of certain MOFs is their ability to undergo stimuli-induced phase transformations with large changes in the accessible pore volume, leading to phenomena like “gate opening”. Theoretical simulations are an indispensable tool in order to understand such processes on a molecular level. However, adsorption phenomena are usually investigated within the approximation of periodic boundary conditions (PBC) and using Grand Canonical methods. This ignores the interface to the gas reservoir and any transport effects, which prevents the investigation of transformation kinetics. Previously, we developed methods to simulate explicit MOF nanocrystallites beyond PBC with the aim to understand size effects. In this work, the results of the natural next step, namely an in silico adsorption experiment for DUT-8 (Cu) nanocrystallites (about 10 nm edge length) in a reservoir of carbon dioxide are presented: Unbiased molecular dynamics simulations reveal a surprisingly rapid gate opening within a few nanoseconds. The first-order phase transition is initiated by a characteristic pore opening at an edge of the crystallite. The anisotropy of the pillared-layer MOF, with its channels along the crystallographic c-axis, leads to a rapid transport along these channels when the pore opening of the MOF proceeds. The simulations allow for an unprecedented view on the molecular mechanism, including the structural transformation of the MOF and the connected transport of the guest molecules into the MOF pores. Already this first attempt of a realistic adsorption simulation beyond PBC revealed the widening of a single channel at the obtuse angle edge of the NC as the secret “Open Sesame!” to open the gate. This confirms that for an in–depth view into the kinetics of adsorption induced phase transformations, an explicit interface between MOF and gas reservoir is pivotal and serves as a basis for further investigations with even larger systems and more realistic surface terminations to be performed in the future.
Source: ChemRxiv
Authors: Rochus Schmid, Larissa Schaper
Institution: Ruhr University Bochum
Language: English
Subfield: Inorganic Chemistry
Field: Chemistry
Domain: Physical Sciences
Open Access status: green
OpenAlex ID: W7208749694