Lotus and taro leaves have hydrophobic surfaces, which in nature consist of micrometer-scale rods or projections that exhibit a super water-repellent property called the lotus effect. The contact angle of a water droplet on such surfaces is 161.0 AE 2.78. Recently, many reports concerning changes in water droplet contact angle as a result of changes in surface morphology and surface polarity have been published. [1] Additionally, changes in photoresponsive wettability have also been reported.[2]Herein, we report a new photoinduced change in surface morphology that provides superhydrophobic properties, obtained by the photoinduced reversible formation of fine fibril structures on coated microcrystalline surfaces. The origin of the reversible formation of fibrils is the photoisomerization of a photochromic diarylethene molecule 1 (see Scheme 1) of a thin film. The reversible changes in surface morphology of a thin film made from photochromic diarylethene 1 were followed by scanning electron microscopy (SEM), optical microscopy, and contact angle measurements of a water droplet. The film was prepared by coating a solution of 1 in chloroform onto a substrate, which gave a contact angle of the water droplet of around 1208. Upon irradiation with UV light, the film surface became superhydrophobic (contact angle 1638). SEM images showed that the surface was covered with microfibrils of diameter around 1 mm. Upon irradiation with visible light, the surface again became flat and recovered the initial contact angle of 1208.Diarylethene derivatives are promising artificial photoresponsive molecules that show reversible transformation between open-and closed-ring isomers with different absorption spectra.[3] As they also show thermally irreversible and fatigue-resistant photochromic performance, [4] intensive studies have aimed at applications such as molecular memories and switches.[5-13] Herein, we report a new function for the cast film of a derivative.There are two approaches to controlling surface wettability. One is to change the surface morphology, because it is known that increasing surface roughness results in a superhydrophobic surface, an effect that is widely observed on lotus leaves. [14,15] Such micrometer-scale rugged or fractal structures were also artificially prepared to make superhydrophobic surfaces. [1b, 16, 17] The other approach is a change of polarity. [18][19][20][21][22] Several reports have attempted to control surface wettability by using photochromic compounds that change the surface polarity.[21] We report changes in photoinduced wettability based on the changes in morphology of a photochromic diarylethene crystal and thin film.The photochromism of a diarylethene, 1,2-bis(2-methoxy-5-trimethylsilylthien-3-yl)perfluorocyclopentene(1 o; Scheme 1), in a hexane solution is shown in the SupportingInformation. The open-ring isomer is colorless, and absorption maxima of the spectrum were observed at l = 255 (e = 2.8 10 4 m À1 cm À1 ) and 325 nm (e = 7.7 10 3 m À1 cm À1 ). Upon UV irradiation (254 n...

Dithienylhexafluorocyclopentene with (R)- or (S)-N-phenylethylamide substituents formed rod-like and 0.2-1.0 microm-thick platelike crystals by sublimation; upon UV irradiation, the crystals bent concavely to the incident light and finally rolled crystals were obtained; the bent crystals were reconverted to flat crystals by visible light irradiation.

Lotus and taro leaves have hydrophobic surfaces, which in nature consist of micrometer-scale rods or projections that exhibit a super water-repellent property called the lotus effect. The contact angle of a water droplet on such surfaces is 161.0 AE 2.78. Recently, many reports concerning changes in water droplet contact angle as a result of changes in surface morphology and surface polarity have been published. [1] Additionally, changes in photoresponsive wettability have also been reported.[2]Herein, we report a new photoinduced change in surface morphology that provides superhydrophobic properties, obtained by the photoinduced reversible formation of fine fibril structures on coated microcrystalline surfaces. The origin of the reversible formation of fibrils is the photoisomerization of a photochromic diarylethene molecule 1 (see Scheme 1) of a thin film. The reversible changes in surface morphology of a thin film made from photochromic diarylethene 1 were followed by scanning electron microscopy (SEM), optical microscopy, and contact angle measurements of a water droplet. The film was prepared by coating a solution of 1 in chloroform onto a substrate, which gave a contact angle of the water droplet of around 1208. Upon irradiation with UV light, the film surface became superhydrophobic (contact angle 1638). SEM images showed that the surface was covered with microfibrils of diameter around 1 mm. Upon irradiation with visible light, the surface again became flat and recovered the initial contact angle of 1208.Diarylethene derivatives are promising artificial photoresponsive molecules that show reversible transformation between open-and closed-ring isomers with different absorption spectra.[3] As they also show thermally irreversible and fatigue-resistant photochromic performance, [4] intensive studies have aimed at applications such as molecular memories and switches.[5-13] Herein, we report a new function for the cast film of a derivative.There are two approaches to controlling surface wettability. One is to change the surface morphology, because it is known that increasing surface roughness results in a superhydrophobic surface, an effect that is widely observed on lotus leaves. [14,15] Such micrometer-scale rugged or fractal structures were also artificially prepared to make superhydrophobic surfaces. [1b, 16, 17] The other approach is a change of polarity. [18][19][20][21][22] Several reports have attempted to control surface wettability by using photochromic compounds that change the surface polarity.[21] We report changes in photoinduced wettability based on the changes in morphology of a photochromic diarylethene crystal and thin film.The photochromism of a diarylethene, 1,2-bis(2-methoxy-5-trimethylsilylthien-3-yl)perfluorocyclopentene(1 o; Scheme 1), in a hexane solution is shown in the SupportingInformation. The open-ring isomer is colorless, and absorption maxima of the spectrum were observed at l = 255 (e = 2.8 10 4 m À1 cm À1 ) and 325 nm (e = 7.7 10 3 m À1 cm À1 ). Upon UV irradiation (254 n...

Supporting information X-ray diffraction: Crystal and Molecular Structure.Suitable colourless block-shaped crystals were obtained by recrystallisation from ethanol. A crystal with the dimensions of 0.49 x 0.21 x 0.18 mm was mounted on top of a glass fibre, and aligned on a Bruker SMART APEX CCD diffractometer (Platform with full three-circle goniometer). The diffractometer was equipped with a 4K CCD detector set 60.0 mm from the crystal. The crystal was cooled to 170(1) K using the Bruker KRYOFLEX low-temperature device. Intensity measurements were performed using graphite monochromated Mo-K α radiation from a sealed ceramic diffraction tube (SIEMENS). Generator settings were 50 KV/ 40 mA. SMART was used for preliminary determination of the unit cell constants and data collection control. The intensities of reflections of a hemisphere were collected by a combination of 3 sets of exposures (frames). Each set had a different φ angle for the crystal and each exposure covered a range of 0.3° in ω. A total of 1800 frames were collected with an exposure time of 10.0 seconds per frame. The overall data collection time was 8.0 h. Data integration and global cell refinement was performed with the program SAINT. The final unit cell was obtained from the xyz centroids of 4487 reflections after integration. Intensity data were corrected for Lorentz and polarization effects, scale variation, for decay and absorption: a multi-scan absorption correction was applied, based on the intensities of symmetry-related reflections measured at different angular settings (SADABS), and reduced to F o 2 . The program suite SHELXTL was used for space group determination (XPREP). 2The unit cell was identified as monoclinic. Reduced cell calculations did not indicate any higher metric lattice symmetry. Space group, P2 1 , was determined from considerations of the unit cell parameters, statistical analyses of intensity distributions : the E-statistics were indicative of a non-centrosymmetric space group. Examination of the final atomic coordinates of the structure did not yield extra crystallographic or metric symmetry elements.The structure was solved by Patterson methods and extension of the model was accomplishedby direct methods applied to difference structure factors using the program DIRDIF. The positional and anisotropic displacement parameters for the non-hydrogen atoms were refined.Some atoms showed unrealistic displacement parameters when allowed to vary anisotropically, suggesting dynamic disorder (dynamic means that the smeared electron density is due to fluctuations of the atomic positions within each unit cell).Hydrogen atoms were constrained to idealized geometries and allowed to ride on their carrier atoms with an isotropic displacement parameter related to the equivalent displacement parameter of their carrier atoms.Final refinement on