Dye, photochromic

Photochromic Organic Dyes. Intensive investigations into this category of substances have led to numerous patent appHcations. Copper—phthalocyanine pigments, organic dyes based on cyanine (Ricoh, Pioneer), naphthochinone (Nippon Denki), and ben2othiopyrane (Sony) (123) have been described. They did not lead, however, to any commercial use. Surveys on the possibiUties of optical data storage with photochromic dyes can be found (124,125). 

New photochromic dyes with electrocycHc reactions have been proposed on the basis of 1,5-electtocycHzation of heterogenous pentadienyl—anions (124). StiH newer are investigations into the photocycHzation of 2,4,6-tri-isoptopylbenzophenones for vinyl polymers ia the glassy state (133). 

The practical use of photochromic dyes as memory layers in erasable and rewritable data storage disks fails not only because of their physical limitations (lacking sensitivity, insufficient stabiHty, low number of cycles), but also because the diode lasers required for switching in the visible range (wavelength between 450 and 600 nm) and the uv-range (around 350 nm) are not available. 

For two-photon memories, a number of media types and reading mechanisms have been used (165). Generally, media comprise two photon-absorbing chromophores dissolved within a soHd polymer matrix. Suitable reversible photochromic dyes are, for example, spiropyrans. Although photochromic materials often suffer from photobleaching, as well as from instability leading to self-erasure, new materials and host environments are under development (172). Bacteriorhodopsin (BR) also has been proposed as a two-photon memory material. 

M., Horiuchi, S., Tanaka, N., Tanigaki, N. and Hiraga, T. (2003) Addition of functional characteristics of organic photochromic dye to nano-structures by selective doping on a polymer surface. Jpn. J. Appl. Phys., 42, L983-L985. 

N. and Hiraga, T. (2004) Selective doping of photochromic dye into nanostructures of diblock copolymer films by vaporization in a vacuum. Chem. Mater., 16, 3469-3475. 

The first chapter of the book deals with leuco-spiropyrans and related spiro compounds, which constitute one of the classes of leuco compounds not of the redox type. Such materials are photochromic, and are of major technical importance. The author, Hiroyuki Nakazumi of the Department of Applied Chemistry at the University of Osaka Prefecture, is well known for his researches in functional dye chemistry, particularly photochromic materials, and he provides a very useful update of the field, covering mechanisms, synthesis, spectra and applications, together with a useful section on approaches to near-infrared absorbing photochromic dyes. 

Photochromic dyes, 20 516 Photochromic glass silver in, 22 658, 686 as a solar energy material, 23 5 Photochromic lenses, 6 588, 601-602 Photochromic materials, 6 587-606 inorganic, 6 589-592 organic, 6 592-601 polyoxometalates, 6 591-592 silver halide-containing glasses, 6 589-590... 

Photochromic dyes can also be found among the various chromophores that have been implemented in molecular glasses. The free volume available in the amor-... 

A medicinal application for a photochromic dye is the use of compounds of the type 379 as near-infrared imaging agents <2005WO16934>. The compounds are used to label amyloid plaques in the brain and aid in the detection of Alzheimer s disease. 

The medicinal use of the photochromic oxazine 379 was discussed in the previous section. The principle of photochromism was shown in Scheme 3, Section 8.06.5.1. Photochromic spirooxazines 101, 116, and 297 that have appeared in this chapter and their various substituted derivatives have been patented as photochromic materials <2003WO42195> and used as photochromic dyes in a microsphere-based sensor <2005USP19954>. The compound 299 is also used as photochromic material <2005S1876>. More detailed information about the applications of spirooxazines can be found in a review <2002RCR893>. The phenoxazine 380 has also been patented for use in optics <2005SUA2246491>. 

This investigation aims for the first time at the stabilization of photoisomers of photochromic dye molecules in molecular sieves by modification of the MCM-41 surface and covalent bonding of dye molecules. Diphenyldichlorosilane is utilized for pre-silylation to warrant an anchoring of the dyes exclusively inside the MCM-41 channel structure. 

Photochromic dyes Photochromic glass Photochromic glasses... 

De Gaouck and LeFevre (25) also studied the conductivity of alcoholic solutions of Malachite Green leucocyanide and Brilliant Green leucocyanide. They found a definite reversibility for the conductance data with alternate irradiation and dark periods only after the first irradiation. Typical resistance for the photochromic dye systems are shown in Figure... 

J. Seto, Photochromic Dyes in Infrared Absorbing Dyes, M. Matsuoka, (ed.), Plenum, New York 1990. 

One recent trend has been away from using a photochromic dye itself merely as an individual component of a solution, polymer film or bulk polymer matrix. Instead, the photochromic is chemically linked to a polymer, which may be a natural polymer such as a cellulose derivative, an enzyme, a protein, or synthetic polymers from acrylates, urethanes, and vinyl compounds. The properties of the polymer can then be modified by external irradiation, and conversely, the properties of the photochromic are modified by the polymer. A recent biochemical example is the photocontrolled binding of monosaccharides to concanavalin A (Con A) modified with spiropyran units.208... 

S.-R Heum, M.-S. Hur, P. M. Kazmaier, and E. Buncel, Thermo- and photochromic dyes Indolino-benzospiropyrans. Part 1. UV-VIS spectroscopic studies of 1, .3,.3-spiro(2 //-1 -benzopyran-2,2 -indolines) and the open-chain merocyanine forms solvatochromism and medium effects on spiro ring formation, Can. J. Chem., 69, 1940-1947 (1991). 

M. Fermigier and P. Jenifer, Flow visualization by photochromic dyes. Application to the motion of a fluid-fluid interface, in Flaw Visualization IV, Proc. Int. Symp. 4th, 1986, (C. Veret, ed.), pp. 153 158, Hemisphere, Washington, DC (1987). 

P.-F. Cevey and U. von Stockar, A tracer system based on a photochromic dye and on fiber optics for measuring axial dispersion of organic liquids in pilot-scale packed columns, Chem. Eng. J., 31, 7-13 (1985). 

D. A. Clarke, Photochromic dyes, in ChemiChromics 95 Conference Papers, Chemichromics 95 Conference, Manchester, England, December 4-5 (1995). 

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