1213261-73-4Relevant academic research and scientific papers
Hydroxypyridinechromene and pyridinechalcone: Two coupled photochrom systems
Leydet, Yoann,Jorge Parola,Pina, Fernando
, p. 545 - 555 (2010)
Substitution of the phenyl group in 2-hydroxychalcones by a 4-pyridine unit dramatically changes the network of chemical reactions of this compound: trans-chalcone-type(Ct), d.v-chalcone-type (Cc), and a hemiketal (hydroxy-4-pyridinechromene) (B) and their protonated forms are formed, but the presence of a flavylium-type cation could not be detected even at very acidic pH values. Moreover, whereas in 2-phenyl-2-benzopyryli urn compounds B and Cc are generally elusive species whose kinetic processes in aqueous solutions occur on the sub-second time-scale, in the present compound these species equilibrate on a timescale four orders of magnitude lower. Complete characterization of the equilibrium and kinetics of the reaction network could thus be achieved by 1H NMR spectros- copy and UV/Vis spectrophotometry. The network of chemical reactions exhibits cis-tmns photoisomerization, as well as photochromism between the hemiketal and the chalcone-type spe-cies. The irradiation of Ct in MeOH/ H2O (1:1) at 365 nm produces B almost quantitatively through two consecutive photochemical reactions: Ct→C c pho-toisomerization followed by Cc→ B photo ring closure with a global quan-tum yield of 0.02. On the other hand, irradiation of B at 254 nm leads to a photostationary state composed by 80% Ct and 20% B, with a quantum yield of 0.21.
