Premium
Photoinduced Ratchet‐Like Rotational Motion of Branched Molecular Crystals
Author(s) -
Zhu Lingyan,
AlKaysi Rabih O.,
Bardeen Christopher J.
Publication year - 2016
Publication title -
angewandte chemie
Language(s) - English
Resource type - Journals
eISSN - 1521-3757
pISSN - 0044-8249
DOI - 10.1002/ange.201511444
Subject(s) - rotation (mathematics) , intermolecular force , rotation around a fixed axis , ratchet , crystal (programming language) , bending , chemical physics , chemistry , crystallography , anthracene , materials science , molecular physics , work (physics) , molecule , photochemistry , physics , geometry , classical mechanics , composite material , thermodynamics , organic chemistry , mathematics , computer science , programming language
Photomechanical molecular crystals can undergo a variety of light‐induced motions, including expansion, bending, twisting, and jumping. The use of more complex crystal shapes may provide ways to turn these motions into useful work. To generate such shapes, pH‐driven reprecipitation has been used to grow branched microcrystals of the anthracene derivative 4‐fluoroanthracenecarboxylic acid. When these microcrystals are illuminated with light of λ =405 nm, an intermolecular [4+4] photodimerization reaction drives twisting and bending of the individual branches. These deformations drive a rotation of the overall crystal that can be repeated over multiple exposures to light. The magnitude and direction of this rotation vary because of differences in the crystal shape, but a typical branched crystal undergoes a 50° net rotation after 25 consecutive irradiations for 1 s. The ability of these crystals to undergo ratchet‐like rotation is attributed to their chiral shape.