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Updated: Aug 14, 2026

Light-driven Molecular Motors on Surfaces for Single Molecular Imaging
Published on: March 13, 2019
Competing Photoisomerization and Excited-State Intramolecular Proton Transfer in a Visible-Light-Driven Salicylidene
Xiaojuan Pang1,2, Yue Yan1, Xueyan Cui3
1School of Materials Science and Physics, China University of Mining and Technology, Xuzhou 221116, China.
Abstract:
We investigate the ultrafast dynamics of a visible-light-driven salicylaldehyde Schiff base-functionalized molecular motor using non-adiabatic molecular dynamics (NAMD) at the orthogonalization-corrected method 2 and the multireference configuration interaction (OM2/MRCI) level. Results reveal a dynamic competitive interplay between E → Z photoisomerization and excited-state intramolecular proton transfer (ESIPT). Importantly, we reveal a direct coupling mechanism between double-bond rotation and proton transfer: within a critical 500-900 fs window, ESIPT transiently stalls rotor rotation while modulating the central double-bond order. The S1 state lifetime is ~1677 fs. Time-resolved fluorescence analysis further predicts rapid fluorescence quenching within ~37 fs accompanied by a pronounced spectral red-shift, indicating that the system quickly enters a dark state with negligible oscillator strength. This study provides atomistic insights into the relaxation pathways of visible-light-driven motors, offering a theoretical basis for designing efficient long-wavelength responsive molecular machines.
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