Efficient Surface Peeling, a Photoinduced Result of Photochromic Diarylethene Crystal by Multistep Light Irradiation

Abstract

Photomechanical materials driven by an external light stimulus have become the focus of much attention. We can operate them in a noncontact way and remotely. Photoinduced bending, one of the typical photomechanical behaviors, is often observed in elongated and thinner crystals, which makes them a promising candidate for a variety of applications. However, the preparation of crystals appropriate for bending behavior is difficult because of the complexity of their molecular structures, preparation conditions, and other factors. Here, an efficient surface peeling of crystals by multistep light irradiation using diarylethene crystals is reported. Thin crystals fabricated by this approach make up less than half the thickness of the original crystals. This shows the potential for the photocontrol of various photomechanical behaviors by the same crystal depending on the irradiation conditions.

A dual-functional 2D coordination polymer exhibiting photomechanical and electrically conductive behaviours

“…[19][20][21][22][23][24][25][26][27] Herein, single crystals exhibit different photomechanical behaviours, such as jumping, splitting or bursting, swelling, rolling and flipping, once irradiated with UV light, which is termed as the photosalient (PS) effect. [28][29][30][31][32][33][34][35] Reasons for the photosalient effect include low photoconversion in densely packed molecular crystals, poor light absorption across a crystal, competing (isotropic) directionality of structure change in many molecules in each crystal, and crystal size effects. The key factor in inducing such a mechanical motion in single crystals is to provide a welldefined anisotropy within the crystals.…”

Recent Advances in Photomechanical Crystals Made from Metal–Organic and Organometallic Complexes

“…Photomechanical crystals as a novel material for photoactuators have the advantages of higher elastic moduli, faster energy transduction, and a well-defined crystal structure. 16,17 Many impressive visual manifestations (contraction, 18,19 expansion, 20 bending, 21 popping, hopping, 22 peeling, 23,24 autonomous movement, 25 jumping, 26 curling, 27 and twisting) 28 of photomechanical crystals are originated from strain accumulation in the crystal interior caused by phase transformations under light irradiation.…”

“…In comparison with other stimuli, light is an attractive stimulus for triggering mechanical behavior due to its superior advantages, including green energy resource, noncontact control, cost-effectiveness and various manipulating methods. , As a consequence, incorporating photoactive group into liquid crystalline polymer, , hydrogels, , or molecular crystals , are an effective strategy to produce rapid and reversible macroscopic motion in photomechanical materials. Photomechanical crystals as a novel material for photoactuators have the advantages of higher elastic moduli, faster energy transduction, and a well-defined crystal structure. , Many impressive visual manifestations (contraction, , expansion, bending, popping, hopping, peeling, , autonomous movement, jumping, curling, and twisting) of photomechanical crystals are originated from strain accumulation in the crystal interior caused by phase transformations under light irradiation.…”

Turning on Photomechanical Responses in Molecular Crystals of Anthracenyl Thiazole Derivatives by Regulating Intermolecular Interactions

“…Mechanically responsive solid-state materials are an essential class of emerging functional solids that can convert different energy forms into mechanical energy under external stimuli such as light, electricity, heat, pressure, humidity, etc. − Among them, photomechanical materials based on solid-state photochemical reactions display various mechanical motions, such as bending, − expanding, − twisting, − curling, , jumping, − peeling, − and wiggling, which are extensively studied due to their potential applications in photoactuators, intelligent switches, waveguides, weight-lifting, and nanorobots. − Instead of embedding photoactive molecules in polymeric chains and networks, photomechanical molecular crystals with long-range anisotropic molecular orientations have superiority. Compared to polymers, crystals that directly consist of small molecules have relatively high elastic moduli and densities and circumvent the concern of chemical compatibility of a photochrome with the polymer matrix.…”