Light‐Induced Bending of Needle‐Like Crystals of Naphthylvinylbenzoxazole Triggered by trans–cis Isomerization

Abstract

New diarylethene derivatives containing benzoxazole (NBO) and benzothiazole (NBT) have been synthesized. Light-induced trans-cis isomerization of NBO and NBT took place in crystals, and only induced the needle-like crystals of NBO to bend backwards away from the UV light source. The movement of the atoms was deemed to take place during the isomerization of NBO; hence, strain would be produced and accumulated rapidly in the surface of crystals exposed to UV light. The uniform release of strain led to the bending of needle-like crystals. The light-induced trans-cis isomerization efficiency of NBT was too low to drive the motion of crystals, which might have originated from the large repulsion between naphthyl and benzothiazole. These results provide a new platform for the transformation of light energy into mechanical energy in molecular crystals through the unimolecular photochemical reaction of diarylethene derivatives.

Design of Collective Motions from Synthetic Molecular Switches, Rotors, and Motors

“…Several other studies have been conducted on thiazolyl derivatives of diarylethene, − but many examples are also available based on 1,2-bis­(thienyl)-perfluorocyclopentene derivatives. ,− Lu et al observed the bending of crystals based on naphthylvinyl benzoxazole and naphthylvinyl benzothiazole . Kobatake and coworkers reported recently an unusual bending behavior of such a crystal that returns back to its initial shape after long UV exposure (λ = 365 nm) .…”

Photomechanical Organic Crystals as Smart Materials for Advanced Applications

“…Apart from trans – cis isomerization of azobenzene, trans – cis isomerization of vinyl groups also exhibited photomechanical effects. The group of Lu reported an example of a naphthylvinylbenzoxazole (NBO) crystal, in which molecules packed in a parallel fashion to form a herringbone‐like shape . The distance between C=C bonds was 6.107 Å, which was too great to allow a normal [2+2] cycloaddition reaction.…”

Quantifiable stretching-induced fluorescence shifts of an elastically bendable and plastically twistable organic crystal

“…Because of the excellent optical and electronic properties as well as the highly ordered and compact packing structures, organic single crystals have a wide range of applications including organic light-emitting diodes, 1,2 organic lasers 3,4 and optical waveguides. [5][6][7][8][9][10][11][12] In recent years, many crystals in response to light, 13,14 heat 15,16 and force stimuli [17][18][19][20] have been reported. For forces that can be applied to a crystal, there are pressures 21 , shear forces, 22 and tensile forces (Fig.…”