Crystallographic Visualization of Cooperative Molecular Motion Underlying the Photomechanical Response of a Diarylethene Crystal
- 1Department of Chemistry and Bioengineering, Graduate School of Engineering, Osaka Metropolitan University, 3-3-138 Sugimoto, Sumiyoshi-ku, Osaka, Not US or Canada, Japan, 558-8585
Abstract
Photomechanical molecular crystals convert molecular-scale photochemical reactions into macroscopic mechanical motion, yet how local structural changes develop into collective crystal deformation remains poorly understood. Here, we directly track the conversiondependent molecular motions underlying the photomechanical response of a diarylethene crystal, DAE-Et, by single-crystal X-ray diffraction. Polarization-selective photoirradiation enabled the preparation of a series of photoreacted single crystals at different conversion levels while maintaining single crystallinity. Detailed disorder analysis revealed two distinct conformations of the closed-ring form, C I and C II , with the relative population of C II increasing with increasing photoconversion. Remarkably, the unreacted open-ring molecules also underwent conversion-dependent conformational reorganization from O toward O′, which correlated with lattice deformation and the macroscopic change in crystal angle. These results reveal the molecular origin of the characteristic induction period in the photomechanical response: photocyclization initially proceeds predominantly with the formation of C I with little lattice reorganization, whereas further photoconversion is accompanied by an increase in the population of C II and conformational reorganization of the surrounding open-ring molecules. Thus, the macroscopic photomechanical response emerges from intermolecularly coupled conformational reorganization involving both photoreacted and unreacted molecules. This work provides direct molecular-level insight into how local photochemical events are translated into cooperative motion and macroscopic mechanical responses in molecular crystals.
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BibTeX
@misc{yoshikawa2026crystallographic,
title = {{Crystallographic Visualization of Cooperative Molecular Motion Underlying the Photomechanical Response of a Diarylethene Crystal}},
author = {Takumu Yoshikawa and Daichi Kitagawa and Seiya Kobatake},
howpublished = {ChemRxiv},
year = {2026},
month = oct,
doi = {10.26434/chemrxiv.15010452/v1},
url = {https://chemrxiv.org/doi/full/10.26434/chemrxiv.15010452/v1},
note = {CC BY-NC-ND},
}
RIS
TY - UNPB
TI - Crystallographic Visualization of Cooperative Molecular Motion Underlying the Photomechanical Response of a Diarylethene Crystal
AU - Takumu Yoshikawa
AU - Daichi Kitagawa
AU - Seiya Kobatake
PY - 2026
DA - 2026/10/14
PB - ChemRxiv
DO - 10.26434/chemrxiv.15010452/v1
UR - https://chemrxiv.org/doi/full/10.26434/chemrxiv.15010452/v1
AB - Photomechanical molecular crystals convert molecular-scale photochemical reactions into macroscopic mechanical motion, yet how local structural changes develop into collective crystal deformation remains poorly understood. Here, we directly track the conversiondependent molecular motions underlying the photomechanical response of a diarylethene crystal, DAE-Et, by single-crystal X-ray diffraction. Polarization-selective photoirradiation enabled the preparation of a series of photoreacted single crystals at different conversion levels while maintaining single crystallinity. Detailed disorder analysis revealed two distinct conformations of the closed-ring form, C I and C II , with the relative population of C II increasing with increasing photoconversion. Remarkably, the unreacted open-ring molecules also underwent conversion-dependent conformational reorganization from O toward O′, which correlated with lattice deformation and the macroscopic change in crystal angle. These results reveal the molecular origin of the characteristic induction period in the photomechanical response: photocyclization initially proceeds predominantly with the formation of C I with little lattice reorganization, whereas further photoconversion is accompanied by an increase in the population of C II and conformational reorganization of the surrounding open-ring molecules. Thus, the macroscopic photomechanical response emerges from intermolecularly coupled conformational reorganization involving both photoreacted and unreacted molecules. This work provides direct molecular-level insight into how local photochemical events are translated into cooperative motion and macroscopic mechanical responses in molecular crystals.
ER -