Photochemical and Thermal Stability of Some Dihydroxyacetophenones Used as UV-MALDI-MS Matrices

Authors

  • Olga I. Tarzi,

    1. CIHIDECAR-CONICET, Departamento de Quimica Organica, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Ciudad Universitaria, Buenos Aires, Argentina
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  • Luciano Di Stéfano,

    1. CIHIDECAR-CONICET, Departamento de Quimica Organica, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Ciudad Universitaria, Buenos Aires, Argentina
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  • Juan E. Argüello,

    Corresponding author
    1. INFIQC, Departamento de Quimica Organica, Facultad de Ciencias Quimicas, Universidad Nacional de Cordoba, Ciudad Universitaria, Cordoba, Argentina
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  • Gabriela Oksdath-Mansilla,

    1. INFIQC, Departamento de Quimica Organica, Facultad de Ciencias Quimicas, Universidad Nacional de Cordoba, Ciudad Universitaria, Cordoba, Argentina
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  • Rosa Erra-Balsells

    Corresponding author
    1. CIHIDECAR-CONICET, Departamento de Quimica Organica, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Ciudad Universitaria, Buenos Aires, Argentina
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  • This article is part of the Special Issue dedicated to the memory of Elsa Abuin.

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 1H nuclear magnetic resonance spectroscopy (1H-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.

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