- Optical and electrochemical properties of cis-1,2-dicyano-1,2-bis(2,4,5-trimethyl-3-thienyl)ethene
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Optical and electrochemical properties of cis-1,2-dicyano-1,2-bis(2,4,5-trimethyl-3-thienyl)ethene (CMTE) have been studied by absorption spectroscopy, cyclic voltammetry, fast sweep voltammetry, and in-situ electrochemical absorptiometry. HOMO and LUMO levels of the CMTE are evaluated from absorption spectra and voltammetry. The lifetimes of unstable cation radicals formed by the electrochemical oxidation of CMTE in closed and open forms are evaluated by the fast sweep voltammetry. Electrochemical isomerization of closed form CMTE is studied by in-situ electrochemical absorptiometry, and the current efficiency is observed to be higher than 600%. The isomerization mechanism and kinetics have been studied taking chain electron transfer reaction between the cation radical of the open form CMTE and the neutral closed form CMTE into consideration.
- Koshido,Kawai,Yoshino
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- Individualized optically induced orientation of photochemical isomers
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We present evidence of individualized optically induced orientation in photoisomers of diarylethene and spiropyran photochromic chromophores. The light-induced orientation studied on the entire UV-vis spectrum of the chromophores shows spectral dependencies which inform about the relative orientation of the directions of the ultra-violet and visible photochemical transitions of the chromophores.
- Ishitobi, Hidekazu,Sekkat, Zouheir,Kawata, Satoshi
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- The photoorientation movement of a diarylethene-type chromophore
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We quantified coupled photoisomerization and photoorientation of a diarylethene-type chromophore in films of poly(methyl methacrylate). We found that the chromophore retains partial memory of its orientation during the A → B UV-induced isomerization and that the chromophore movement is thermalized after the A←B green light induced isomerization. The isomerization quantum yields are φAB/365 = 1.1 φAB/405 = 0.32, and φBA/532 = 0.16, and the transitions at 365 (405) and 532 nm of the B isomer are oriented at an angle of 74.3 (61.3)° to each other. This relative orientation of the transition dipoles is rationalized by MOPAC molecular orbital calculations.
- Ishitobi,Sekkat,Irie,Kawata
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- Photochemically induced fluorescence control with intermolecular energy transfer from a fluorescent dye to a photochromic diarylethene in a polymer film
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The photochemically induced fluorescence control with intermolecular energy transfer from a fluorescent dye to a photochromic diarylethene in a polymer film was discussed. The high fluorescence contrast and the complete on-off of fluorescence in the polymer film was realized by using 4,4-difluoro-1,3,5,7,8-pentamethyl-4-bora-3α,4α-diaza-s-indacen e (PM546) as a fluorescent dye and cis-1,2-dicyano-1,2-bis(2,4,5-trimethyl-3-thienyl)ethane (CMTE) as a photochromic compound. The excitation energy transfer between a fluorescent dye and a closed form of CMTE was the mechanism used for fluorescence quenching.
- Murase, Seiichiro,Teramoto, Madoka,Furukawa, Hidemitsu,Miyashita, Yoshiharu,Horie, Kazuyuki
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- Thermally Irreversible Photochromic Systems. Reversible Photocyclization of Diarylethene Derivatives
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The reversible photocyclization of 1,2-diarylethene derivatives having methyl-substituted heterocyclic rings has been found to constitute a photochromic system, which is both thermally irreversible and fatigue resistant. cis-1,2-Dicyano-1,2-bis(2,4,5-trim
- Irie, Masahiro,Mohri, Masaaki
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- Shear stress- and visible light-induced photochromism on diarylethene
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Light irradiation experiments on diarylethene, cis-1,2-dicyano-1,2-bis(2,4,5-trimethyl-3-thienyl)ethane (CMTE), under shear stress have been performed. From the results, it is apparent that the combination of shear stress and visible light of around 500 nm could induce the photoisomerization of CMTE to the closed-ring isomer. The present work shows that shear stress could adjust the wavelength oflight for the photochromism from ultraviolet light region to visible light.
- Inoue, Takeshi,Inokuchi, Makoto
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- Spectral, conformational and photochemical analyses of photochromic dithienylethene: Cis-1,2-dicyano-1,2-bis(2,4,5-trimethyl-3-thienyl)ethene revisited
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The conformational equilibrium and thermodynamic parameters of cis-1,2-dicyano-1,2-bis(2,4,5-trimethyl-3-thienyl)ethene (1a) and its trans derivative 1c are presented. Irradiation of both compounds was carried out by using 365 nm light, which affects the cis/trans isomerisation process, whereas irradiation with 405 nm light preferentially promotes the formation of the cyclised product. Prolonged irradiation of 1a at 365 nm leads to the formation of a new derivative showing photochromic properties. Evidence for the formation of the novel derivative is presented, and details of its photochromic properties were investigated; a tentative mechanism has also been proposed. The equilibrium between parallel and antiparallel forms of cis- and trans-1,2-dicyano-1,2-bis(2,4,5-trimethyl-3-thienyl)ethene was studied by NMR spectroscopy. Photocyclisation or cis/trans isomerisation was induced by irradiation with 405 or 365 nm light. Extended irradiation of the cis compound generated two peroxy derivatives that thermally convert into a new coloured compound with its own photochromic properties. Copyright
- Erko, Firealem G.,Berthet, Jerome,Patra, Abhijit,Guillot, Regis,Nakatani, Keitaro,Metivier, Remi,Delbaere, Stephanie
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p. 7809 - 7814
(2013/12/04)
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- Photochromic one-dimensional nanostructures based on dithienylethene: Fabrication by light-induced precipitation and reversible transformation in the nanoparticle state
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A convenient protocol has been developed to fabricate one-dimensional nanostructures of a photochromic molecule cis-l,2-dicyano-l,2-bis(2,4,5- trimethyl-3-thieny1)ethene (CMTE). Light-induced self-assembled nanorods and nanowires of the colored form were obtained in situ under UV light irradiation in aqueous dispersion and redissolved under green light. Reversible and fatigue-resistant optical switching in the nanoparticle state was demonstrated. The Royal Society of Chemistry 2012.
- Patra, Abhijit,Metivier, Remi,Brisset, Francois,Nakatani, Keitaro
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supporting information; experimental part
p. 2489 - 2491
(2012/04/04)
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