title: Photochemical and thermal stability of some dihydroxyacetophenones used as UV-MALDI-MS matrices.
abstract: 2,4-, 2,5-, 2,6- and 3,5-dihydroxyacetophenone (DHA) used as matrices in matrix-assisted ultraviolet laser desorption/ionization mass spectrometry (UV-MALDI-MS) were studied by steady-state and transient absorption spectroscopy, together with DFT calculations at the B3LYP level of theory. All compounds have low fluorescence quantum yields, possibly due to an efficient excited-state intramolecular proton transfer (ESIPT). Laser flash photolysis (LFP) results showed that, only for 2,4-DHA, a phototautomer could be detected at λ = 400 nm. Their photochemical stability in solution at different wavelengths and conditions was analyzed by UV-Vis and (1)H nuclear magnetic resonance spectroscopy ((1)H-NMR), together with thin layer chromatography and ultraviolet laser desorption/ionization mass spectrometry (UV-LDI-MS). Only 3,5-DHA showed decomposition when irradiated, probably because phototautomerization is not possible. Thermal stability studies of these compounds in solid state were also conducted.
authors.affiliation: CIHIDECAR-CONICET, Departamento de Quimica Organica, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Ciudad Universitaria, Buenos Aires, Argentina.
authors.forename: Olga I
authors.initials: OI
authors.lastname: Tarzi
authors.forename: Luciano
authors.initials: L
authors.lastname: Di Stéfano
authors.forename: Juan E
authors.initials: JE
authors.lastname: Argüello
authors.forename: Gabriela
authors.initials: G
authors.lastname: Oksdath-Mansilla
authors.forename: Rosa
authors.initials: R
authors.lastname: Erra-Balsells
mesh_terms: D000098:Acetophenones / Q000737:chemistry*; D010777:Photochemistry; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization / Q000379:methods*; D013056:Spectrophotometry, Ultraviolet / Q000379:methods*
chemical_list: D000098:Acetophenones; C019339:2,6-dihydroxyacetophenone