S. Hattori, S. Vandendriessche, T. Hirano, F. Sato, G. Koeckelberghs, T. Verbiest and K. Ishii
"Molecular Power Spring: Circular Dichroism Inversion of Polythiophene Aggregates from Right-handed Helix to Left-Handed Helix"
J. Phys. Chem. B, 123, 2925-2929 (2019).
(Supplementary Cover)

https://pubs.acs.org/doi/abs/10.1021/acs.jpcb.8b11832

In molecular rotors, a type of molecular machine, spontaneous rotors without the need for an external stimulus are promising because conventional molecular rotors require a continuous energy supply. In this study, we demonstrate spontaneous transformation from　kinetically favored metastable right-handed helical aggregates to thermodynamically stable left-handed helical aggregates after an evaporation procedure. In addition, we propose the conditions for preparation of metastable right-handed helical aggregates, whose chirality can be spontaneously inverted, based on kinetic analysis. This molecular power spring will be useful for designing new types of molecular machines.

• S. Hattori, S. Vandendriessche, G. Koeckelberghs, T. Verbiest, and K. Ishii
  “Evaporation Rate-Based Selection of Supramolecular Chirality”
  Chem. Commun., 53, 3066 (2017).