14933-76-7Relevant articles and documents
Design of crystal packings of styryl heterocycles and regularities of [2+2] photocycloaddition in their single crystals 8.* Topochemical [2+2] autophotocycloaddition and back reaction in styryl dye of the benzothiazole series
Kuzmina,Vedernikov,Lermontova,Howard,Alfimov,Gromov
, p. 1726 - 1739 (2013)
New styryl dye of the 2-benzothiazole series was synthesized. The new dye contains two methoxy groups in the benzene ring and tosylate counterion. The [2+2] photocycloaddition (PCA) of the dye was studied in the polycrystalline film and in single crystal. Two modifications of the dye cocrystallizate with hydroquinone differed in the ratio of components were obtained, and their ability to enter PCA was studied. According to the X-ray diffraction data, molecular cations of the dye form stack packings either of syn- head-to- tail type or relatively isolated stacking dimers. In all cases, the ethylene bonds of the adjacent cations are brought together and antiparallel, favoring PCA to form the centrosymmetric rctt-isomer of 1,2,3,4-tetrasubsti- Tuted cyclobutane. In two cases, the PCA reaction proceeded as the single crystal-to-single crystal transformation. Hydrogen bonds in crystals including hydroquinone molecules strength en the crystal packing retarding the PCA. The back photoreaction (retro-PCA) was detected: it occurs without single crystal decomposition and results in the accumulation of the initial styryl dye in crystal consisting of the cyclobutane derivative. This is the first example of such a transformation in single crystals.
Photophysics of cyanine dyes on surfaces: Laser-induced photoisomer emission of 3,3′-dialkylthiacarbocyanines adsorbed on microcrystalline cellulose
Oliveira, Anabela S.,Almeida, Paulo,Ferreira, Luis Filipe Vieira
, p. 459 - 473 (2007/10/03)
The photophysics of three thiacarbocyanine dyes, 3,3′-dimethylthiacarbocyanine iodide (DMTCC), 3,3′-diethylthiacarbocyanine iodide (DETCC), and 3,3′-dipropylthiacarbocyanine iodide (DPTCC) was studied when adsorbed on microcrystalline cellulose in the concentration range from 5.0 · 10-4 to 10.0 μmol g-1. Using ground-state diffuse reflectance absorption technique, only H aggregate formation was detected for all the probes. The amount of aggregate formed depends on the hydration degree of the sample, always decreasing with sample dryness. The fluorescence quantum yields for all the adsorbed dyes are one order of magnitude higher than those observed in nonviscous solvents, being 0.98 for DMTCC, 0.96 for DETCC, and 0.63 for DPTCC. Laser-induced fluorescence emissions were recorded (using an intensified-charge-coupled-device detection system) as a function of the laser power, showing that for dry concentrated samples irradiated with high laser intensity, a second fluorescence emission band (bathochromically shifted relative to the monomer emission) was detected. This emission shows a supralinear dependence on laser power. The new emissions here detected arise from fluorescent photoisomers formed via singlet monomers, by a two-photon absorption process.
Carbonylmethylene-heterocyclic compounds containing trihalogenomethyl groups, process for their preparation, and light-sensitive mixture containing the compounds
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, (2008/06/13)
Disclosed is a compound of the general formula STR1 wherein L=H or CO--(R1)n (CX3)m, M=alkylene, alkenylene, Q=S, Se, O, dialkylmethylene, alken-1,2-ylene, 1,2-phenylene or N-R, with M+Q together forming 3 or 4 ring members, R=alkyl, aralkyl or alkoxyalkyl, R1 is an aromatic group and X=Cl, Br or I, with n=O and m=1 or n=1 and m=1 or 2. The compounds, on exposure, eliminate HX and form free radicals and are therefore highly effective as acid donors and free radical initiators for photochemical processes.
