Photoinduced shape changes of diarylethene single crystals: correlation between shape changes and molecular packing

Abstract

Correlation between the photoinduced shape changes of diarylethene single crystals and their molecular packing in the crystals was studied. Crystals of 1,2-bis(5-ethyl-2-phenyl-4-thiazolyl)perfluorocyclopentene (3a) and 1,2-bis(2-isopropyl-5-phenyl-3-thienyl)perfluorocyclopentene (4a) showed similar photoinduced deformation from square to lozenge as that of 1,2-bis- (2-ethyl-5-phenyl-3-thienyl)perfluorocyclopentene (1a). Although these three diarylethenes have different electronic structures and exhibit different colours upon UV irradiation, the crystallographic structures and molecular packing of the crystals are very similar to each other. The result indicates that the deformation mode is determined by the packing mode of component molecules in the crystal. X-Ray crystallographic analysis of a micrometre-sized crystal 1a (20 x 15 x 8 microm) prepared by sublimation revealed that the small-size crystal, which shows photoinduced deformation, has the same crystal structure as that of the large bulk crystal.

Dependence of Photoinduced Bending Behavior of Diarylethene Crystals on Ultraviolet Irradiation Power

“…Diarylethenes are well known as photochromic compounds that can reversibly change their chemical and physical properties upon alternating irradiation with UV and visible light, and can undergo photochromic reactions even in polymer films and crystalline phases as well as in solution. 1,2 Diarylethene crystals exhibit various photomechanical motions such as contraction, 3,4 expansion, 5 bending, 3,[5][6][7][8][9][10][11][12] separation, 13 rolling, 6 and twisting. 14 Other photochromic compounds that exhibit photomechanical motion in their crystal state, such as furylfulgides, 15 azobenzenes, 16,17 salicylideneanilines, 18 and anthracene carboxylates [19][20][21][22][23][24] have been reported.…”

Crystal structure of the meta-stable intermediate in the photomechanical, crystal-to-crystal reaction of 9-tert-butyl anthracene ester

“…In order to generate useful amounts of motion and force, ordered assemblies of photoreactive subunits must be utilized. [19][20][21][22] The bimorph mechanism for photomechanical response requires generating an asymmetric spatial mixture of reactant and product molecules within the crystal. 2,3 Molecular crystals have also attracted recent attention as dynamic entities, 4,5 and crystals composed of photoreactive molecules have been shown to undergo photoinduced shape changes, like bending, coiling, twisting, and jumping.…”

“…In 2006, we demonstrated that nanorods composed of 9TBAE could expand by up to 15% upon irradiation, 26 while larger crystals shattered under illumination. In situ X-ray diffraction measurements can provide valuable information about molecular motions in photomechanical molecular crystals, 11,20,29,30 but it proved impossible to obtain a single-crystal X-ray structure for the SSRD. The SSRD has a different packing from the equilibrium dimer crystal obtained from solution growth (the "solution grown dimer" or SGD).…”

Quantitative Evaluation of Photoinduced Bending Speed of Diarylethene Crystals

“…The photomechanical crystals have attracted much attention because they can work without any direct contact or electrical wires [9]. Various types of photomechanical behaviors such as contraction [8,10], expansion [11], OPEN ACCESS bending [8,[11][12][13][14][15][16][17], separation [18], twisting [19], and rolling [12] have been reported so far. Although photochromic compounds such as diarylethenes [8,19], furylfulgide [20], azobenzene [21,22], anthracene carboxylates [23][24][25][26][27][28], salicylideneaniline [29], 4-chlorocinnamic acid [30], 1,2-bis(4-pyridyl)ethylene salt [31], benzylidenedimethylimidazolinone [32], and others [33] exhibit photochemical reactions in the crystalline phase, their photomechanical motions in the crystal are almost bending.…”