UTokyo scientists could control molecular motion by adjusting the molecular twisting strength.
Molecular machines require flexible molecules that can show a range of motions such as twisting. In the macroscopic world, a loosely twisted object unwinds easily, while a tightly twisted object does not. Replicating that at a molecular level is not easy. In a study published in Nature Communications, UTokyo researchers synthesized selectively twistable isomers of a trinuclear Pd-macrocycle, which can exhibit different molecular behaviors such as helicity inversion.
The team synthesized tightly and loosely twisted isomers of the molecule. Moreover, the speed of helicity inversion motion between the isomers differed greatly. The loosely twisted isomer can invert between two different helicities, and the tightly twisted isomer relaxes to the loosely twisted isomer without helicity inversion (see Figure). This difference between the two isomers is due to the absence or presence of configurational inversion of nitrogen atoms in the macrocycle. In other words, they differ in the inversion mechanism due to different degrees of their ring twisting.
The findings make it possible to design advanced molecular machines that can exhibit complex motions. Previous studies have shown rotation and translation motions. With twisting and kinetic speed control, this study brings us closer to reproducing a wider range of motions at the level of molecules. This is the first example of controlled motion speed at a molecular level by changing the degree of molecular twist.
Figure: By varying the degree of twist of a cyclic molecule, the speed of helicity inversion motion could be controlled.
For more details, please read the article:
Authors: Tomoki Nakajima, Shohei Tashiro, Masahiro Ehara and Mitsuhiko Shionoya 2023.
Title: Selective synthesis of tightly- and loosely-twisted metallomacrocycle isomers towards precise control of helicity inversion motion.
Journal Name: Nature Communications.
DOI: 10.1038/s41467-023-43658-5
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