A photochemical method to evidence directional molecular motions

• Published in: Nature communications Vol. 14; no. 1; p. 4595
• Main Authors: Regen-Pregizer, Benjamin Lukas, Ozcelik, Ani, Mayer, Peter, Hampel, Frank, Dube, Henry
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 31.07.2023; Nature Publishing Group; Nature Portfolio
• Subjects: 119/118; 140/131; 140/58; 639/301/923/3931; 639/638/403/934; 639/925/927/339; Humanities and Social Sciences; Intermediates; Molecular machines; Molecular motors; multidisciplinary; Photochemicals; Rotation; Science; Science (multidisciplinary)
• ISSN: 2041-1723; 2041-1723
• DOI: 10.1038/s41467-023-40190-4

Light driven synthetic molecular motors represent crucial building blocks for advanced molecular machines and their applications. A standing challenge is the development of very fast molecular motors able to perform rotations with kHz, MHz or even faster frequencies. Central to this challenge is the direct experimental evidence of directionality because analytical methods able to follow very fast motions rarely deliver precise geometrical insights. Here, a general photochemical method for elucidation of directional motions is presented. In a macrocyclization approach the molecular motor rotations are restricted and forced to proceed in two separate ~180° rotation-photoequilibria. Therefore, all four possible photoinduced rotation steps (clockwise and counterclockwise directions) can be quantified. Comparison of the corresponding quantum yields to the unrestricted motor delivers direct evidence for unidirectionality. This method can be used for any ultrafast molecular motor even in cases where no high energy intermediates are present during the rotation cycle. Light driven synthetic molecular motors represent crucial building blocks for advanced molecular machines and their applications but the development of very fast motors remains challenging. Here the authors restrict fast molecular motor rotations and force them to proceed in two separate rotation-photoequilibria enabling them to elucidate the directionality of the motion.