24531-81-5Relevant academic research and scientific papers
Convenient Chemical Actinometer with 2-Hydroxy-4'-methoxychalcone
Matsushima, Ryoka,Mizuno, Hirotaka,Kajiura, Atsushi
, p. 1762 - 1764 (1994)
The quantum yields for the photochemical conversion of 2-hydroxy-4'-methoxychalcone into the flavylium ion are in the range of 0.25 - 0.35 in acetic acid and 0.14 - 0.2 in aqueous ethanol at pH 2, depending on the wavelength of UV light. The quantum yields are essentially constant against any changes in the light intensity, temperature, or substrate concentration, which is a favorable feature regarding use as a convenient chemical actinometer. A one-photon mechanism involving excited-state-proton-transferred tautomer is proposed.
Photochromic Properties of 2-Hydroxychalcones
Matsushima, Ryoka,Miyakawa, Katsuhide,Nishihata, Minoru
, p. 1915 - 1916 (2007/10/02)
Photochemical and thermal interconversions between 2-hydroxychalcones (λmax 330-360 nm) and flavylium ions (400-460 nm) have been studied in dilute aqueous ethanol solutions.The reactions were fairly clean and recyclizable, though varied with substituents and pH.The quantum yields for photochemical coloration were about 0.1 or less.
Hydration of the Flavylium Ion. 3. The Effect of 3-Alkyl Substitution
Devine, David B.,McClelland, Robert A.
, p. 5656 - 5660 (2007/10/02)
An investigation is reported of the transformations undergone by four flavylium salts-two 3-methyl-substituted cations, the 3-methylflavylium ion, and the 4'-methoxy-3-methylflavylium ion-and two cations where an ethylene unit bridges the 3-position and the 2'-position of the phenyl ring, the 5,6-dihydrobenzoxanthylium ion, and the 3-methoxy-5,6-dihydrobenzoxanthylium ion.Three transformations have been identified and studied-a rapid and reversible hydration of the cations to produce a pseudobase, the rapid reversible ring opening of this pseudobase to a (Z)-chalcone, and the slow irreversible cis-trans isomerization of this species to an (E)-chalcone.Rate and equilibrium constants have been obtained for these processes and compared with values previously obtained for 3-H-substituted flavylium ions, the parent flavylium ion itself, and the 4'-methoxyflavylium ion.There is little effect of the alkyl substitution on the pseudobase: (Z)-chalcone equilibration.The ethylene-bridged systems undergo cis-trans isomerization at a similar rate to the 3-H systems, while the 3-methyl systems undergo this reaction about 30 times more slowly.The most significant effect, however, is seen on the flavylium ion hydration equilibrium, the bridged cations being about 2 orders of magnitude more stable than their 3-H-substituted counterparts with these in turn 2 orders of magnitude more stable than the 3-methyl analogues.To explain this, it is proposed that there is a steric interaction involving the 3-hydrogen or 3-methyl substituent and an ortho hydrogen on the nearby phenyl ring, resulting in a twisting of this ring so that it is not coplanar with the benzopyrylium portion of the cation.
