Diastereoselective cyclization of a dithienylethene switch through single crystal confinement

Abstract

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

Photoresponsive rolling and bending of thin crystals of chiral diarylethenes

“…1), with chiral, (R)-N-phenylethylamide groups at both ends of the molecule, undergo diastereoselective cyclisation in the crystalline state under UV irradiation. 6 We also demonstrated that chiral N-phenylethylamide-based diarylethenes form organogels and that the properties of the fibres as well as the transmission of chiral information from the molecular to the supramolecular level can be controlled reversibly by light. 7 In the present communication we disclose the photoresponse of thin crystals of 1oRR, and 2oRR, and show for the first time that reversible light-induced bending of crystals in both a convex and a concave manner can be achieved.…”

Crystal structure of 3,3,4,4,5,5-hexafluoro-{[1-(2-ethyl-3-benzothienyl)-2- (2-n-heptyl-5-formyl)]-thien-3-yl}-cyclopent-1-ene, C27H26F6OS2

“…The two isomers differ from one another not only in the absorption spectra but also in various physical and chemical properties, and the instant property changes by photoirradiation without processing lead to their use in various optoelectronic devices, such as optical memory [3] and optical switches [4]. Among various types of photochromic compounds, the diarylethenes bearing thiopheneor benzothiophene-derived are the most promising candidates for the applications because of their excellent fatigue resistant [5] and outstanding thermally irreversible photochromic performance [6]. Although agreat number of publications concerning this class of diarylethenes have been reported so far [1,[7][8][9], most of them are symmetrical and amorphous diarylethenes, reports on asymmetrical and crystalline derivatives are very rare [10][11][12].…”

Crystal structure of 1,2-bis(2-methoxylphenyl)perfluorocyclopentene, C19H14F6O2

“…Photochromic diarylethene compounds have attracted remarkable interests because of their potential application as photoelectronic device materials [1], due to the good chemical and thermal stability, remarkably fatigue resistance and sensitivity [2][3][4][5][6]. To date, a large number of diarylethenes have been developed.…”