Visible‐Light‐Triggered Actuators Based on the Molecular Crystals of Anthracenecarbonitrile Undergoing Reversible [4+4] Cycloaddition

Abstract

The photomechanical effects of crystals of halogen-substituted 9-anthracenecarbonitrile were investigated. The needle-like crystals of 10-fluoroanthracene-9-carbonitrile (FCNA) bend rapidly under irradiation with 365 nm, 410 nm light and even white light, and the bent crystal could almost recover to its original shape upon exposure to 254 nm light or heating. The reversible photo-induced mechanical behaviors originated from [4 + 4] cycloaddition and the reverse reaction. This type of photoactuator, in response to light irradiation over a broad wave-length range from UV to the visible region, might have important applications in biomimetic systems, biomedicine, artificial muscles, and smart microrobotics. The rapid photoinduced mechanical movements of the crystals inspired us to fabricate a hybrid polymer film of polyvinylidene difluoride incorporated with the microcrystals of FCNA, which not only showed bending toward or away from the light source depending on the initial bending direction of the film, but also could lift small objects induced by remote light.

Fast photoactuation of elastic crystals based on 3-(naphthalen-1-yl)-2-phenylacrylonitriles triggered by subtle photoisomerization

“…21 In the crystalline materials the photomechanical effects of jumping, [22][23][24][25] twisting, [26][27][28] shape deformation, 14,29,30 explosion, 31,32 curling, 33,34 bending, [35][36][37][38] and even rocking 39 could be driven by photo-induced electrocyclizations, [40][41][42] cis-trans isomerization, [43][44][45] tautomerization, 46,47 and cycloaddition reactions. 14,[48][49][50][51][52][53] Although rapid photomechanical movements are observed in various crystals, continual operation is usually essential for the applications. Therefore, the crystals with reversible deformation and retained integrity during movement have become attractive candidates.…”

Organic Single Crystal/Polymer Hybrid Actuator with Waveguide, Low Temperature, and Humidity Actuation Properties

“…The absorption/emission spectra and photophysical data of TFMAC in cyclohexane and microcrystals are presented in Figure and Table S1, respectively. As observed in Figure , the absorption peaks of the compound in cyclohexane were 369, 384, and 406 nm, which were derived from π–π* transition . The above three peaks were a group of vibrational peaks, and the main absorption peak at 406 nm mainly derived from the electronic transition from HOMO to LUMO (Figure S2, Table S2).…”

“…The synthesis route of 10-(trifluoromethyl)anthracene-9carbonitrile (TFMAC) is outlined in Figure S1. Using anthracene-9-carbonitrile as the initial raw material, TFMAC was obtained through two-step reactions of bromination 49 and trifluoromethylation (Figure S1). The absorption/emission spectra and photophysical data of TFMAC in cyclohexane and microcrystals are presented in Figure 1 and Table S1, respectively.…”

“…As observed in Figure 1, the absorption peaks of the compound in cyclohexane were 369, 384, and 406 nm, which were derived from π−π* transition. 49 The above three peaks were a group of vibrational peaks, and the main absorption peak at 406 nm mainly derived from the electronic transition from HOMO to LUMO (Figure S2, Table S2). 50 Furthermore, due to the J-aggregation of the molecules, both the absorption and emission spectra in the microcrystals were significantly red-shifted compared to the solution (Figure S3).…”

Cocrystal Strategy to Harmonize the Photochemical Reactivity of Styrylquinolines and the Photoactuation Performance of the Molecular Crystals

“…Particularly, the photo-induced moving can be remotely operated without contact, showing high spatiotemporal resolution . There are a large number of photomechanical molecular crystals that have been reported, mainly concentrating on the derivatives of azobenzene, , olefin, , diarylethenes, , anthracene, and so forth. As for the olefin-based molecular crystals, [2 + 2] cycloaddition between adjacent CC double bonds would trigger the macroscopic mechanical motions.…”