Guest-induced amorphization and cage-selective guest dynamics in solid organic clathrates.

Authors

Chang Yeop Oh, Sol Geo Lim, Hye Rim Choi, Donghyun Moon, Chiho Sung, Seonghwan Park, Sun Ha Kim, Jeasung Park, Minjun Cha, Ji-Ho Yoon

Published in

Physical chemistry chemical physics : PCCP. Oct 02, 2026. Epub Oct 02, 2026.

Abstract

Solid-state host-guest reactions, in which a crystalline solid transforms upon direct uptake of a gaseous guest, represent a class of phase transformation whose molecular-scale mechanisms remain poorly understood. Here, we exploit xenon-loaded hydroquinone clathrates as a model system to reveal the molecular mechanisms governing both the formation pathway and the cage-filling behavior of solid host-guest materials, by combining structural analysis, spectroscopy, kinetic modeling, and molecular simulations. The phase transition is initiated by guest-induced amorphization (GIA) at the hydroquinone surface, producing transient quasi-liquid layers (∼11 Å thick) that facilitate nucleation and growth of the clathrate framework. The resulting amorphous interface facilitates local nucleation while limiting further guest penetration, followed by diffusion-controlled growth through the developing clathrate layer. We further show that two structurally distinct cage environments, designated C_β1 and C_β2 based on hydrogen-bond directionality, govern cage-selective guest occupancy and release. The exceptional thermal stability and high gas storage capacity (2.77 mmol g^-1) of the clathrate arise from strong host-guest van der Waals interactions that stabilize energetically favorable cage geometries. These findings establish GIA as a general initiating mechanism in solid-state host-guest reactions and demonstrate that cage-selective guest dynamics govern both the formation pathway and guest release behavior. The resulting mechanistic framework provides molecular-level design principles transferable to porous crystalline materials, including metal-organic frameworks, porous organic cages, and hydrogen-bonded organic frameworks.

PMID:
42825590
Bibliographic data and abstract were imported from PubMed on 02 Oct 2026.

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