A strategy to obtain photochromism from the network of chemical reactions originated by flavyliurn compounds in solution is described. This strategy is particularly useful for flavyliurn salts bearing amino groups which give rise to a variety of beautiful colors but lack photochemistry in water. The trans-chalcone of 7-(N,Ndiethylamino)-4'-hydroxyflavylium interacts strongly with CTAB micelles defining a yellow dark state. Upon irradiation, the system switches to a pink-red state emerging from the flavylium cation that is formed inside the micelle and ejected to the bulk aqueous phase. The photochemical product reverts back to the transchalcone adduct with the micelle in the dark. The thermodynamics as well as the kinetics of the photochromic system were studied in detail. The best color contrast is obtained at pH = 4.25 with (D = 0.001 and a recovery lifetime of approximately 3 h. This photochromic system works with no need of changing the pH, which constitutes an important improvement over previously described systems dependent on pH jumps.
ISI Document Delivery No.: 221XKTimes Cited: 11
Cited Reference Count: 22
Gomes, Raquel Parola, A. Jorge Laia, Cesar A. T. Pina, Fernando
Laia, Cesar/C-8651-2011; Pina, Fernando/C-8161-2011; Parola, A. Jorge/F-4048-2010; REQUIMTE, AL/H-9106-2013
Parola, A. Jorge/0000-0002-1333-9076;
Amer chemical soc
Washington