Light-induced transformation

Zepp, R.G., Wolfe, N.E., Gordon, J.A., and Fincher, R.C. Light-induced transformations of methoxychlor in aquatic systems, / Agric. FoodChem., 24(4) 727-733, 1976. 

The molecular event that triggers the visual process is the light-induced transformation of the 11-c form of retinal in rhodopsin to the aJi-trans form. 

Naito T, Inabe T, Niimi H, Asakura K (2004) Light-induced transformation of molecular materials into devices. Adv Mater 16 1786-1790... 

Sutherland, B.M., Cimino, V.S., Delihas, M., Shih, A.G., and Oliver, R.P. (1980). Ultraviolet light-induced transformation of human cells to anchorage-independent growth, Cancer Res. 40,1934. 

Light-induced transformations over fluorinated titania (TiOi/F) cannot be initiated either by =Ti— 0 (OHads), due to the lack of =Ti—OH groups, or by SET from a surface complexed substrate, due to the fluoride competition. In addition to these major effects, the adsorption of molecular oxygen can be affected also and the surface charge is dramatically decreased. The last effect may be important particularly for charged substrates and intermediates and for the possibility of interfacial electron transfer. 

Diarylethenes are promising synthetic photoswitchable molecules because of their outstanding fatigue-resistance in reversible light-induced transformation between two isomers with different absorption spectra.21,22 The tt-conjugation extends over the entire molecular in the closed form, whereas it is restricted to each half of the molecule in the open form. As a consequence, the closed form is expected to exhibit better electrical conductance than the open form. The two forms are referred to as the on and off states of the switch, respectively. The UV-vis spectra of this molecular switch in toluene show that the wavelengths that can be used for on to off switching are 420 < A< 650 nm, and 300 < A< 350 nm for the reverse operation. 

The formation and the dissociation of the supramolecular donor-acceptor complex between the xanthene dye and the bipyridinium unit can therefore be triggered by the light-induced transformation of the latter component to photoisomers exhibiting high or low affinities for the electron donor, respectively. 

Azobenzene derivatives constitute a family of dye molecules well known for their photochromic properties, which are due to the reversible cis-trans photoisomerization. " Figure 16.11 shows a photoisomerization process of azobenzene. Azobenzene derivatives have two geometric isomers the trans and the cis forms. The isomerization reaction is a light- or heat-induced inter-conversion of the two isomers. Because the trans form is generally more stable, the thermal isomerization is generally in the direction of from cis to trans. Light induces transformations in both directions. 

Trentelman, K., Stodulsld, L., and Pavlosky, M., 1996, Characterization of pararealgar and other light-induced transformation products from realgar by Raman microspectroscopy Analytical Chemistry, p. 1755-1761. 

Z pp and co-workers (1976) found that photolysis of methoxychlor, although much more rapid than that of DDT, is still a very slow environmental process. The major product of light-induced transformation is l,l-bis(p-methoxyphenyl)-2,2-dichloroethylene (DMDE, 24). This product is subject to rapid photodegradation in both aqueous and hydrocarboi) media. 

Zepp, R. G., N. L. Wolfe, J. A. Gordon, and R. C. Fincher. 1976. Light-induced transformations of methoxychlor in aquatic systems. J. Agric. Food Chem. 24, 727-733. 

Many previous studies have shotm that the light-induced transformation of certain pollutants Is greatly accelerated In natural waters compared to distilled water. Oxidations via photoproduced H2O2 may account for the results of some of these Investigations. 

Light-induced transformations from one structure to another have been studied with many modified polypeptides [13, 14] bearing pendant photochromic groups such as azobenzene or spiropyran groups. Typical examples are the modified poly(L-glutamic acids) PGA-1 and PGA-2 presented in Chart 5.5. 

Borek C, Ong A, Morgan WF et al. Inhibition of X-ray- and ultraviolet light-induced transformation in vitro by modifiers of poly(ADP-ribose) synthesis. Radiat Res 1984 99(2) 219-227. 

Light-induced transformations of 1,2-dihydroquinolines Opening of the heterocycle, radical formation and photoinduced proton transfer 12UK983. 

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