Substituent Effects on the Photophysical Properties of Pterin Derivatives in Acidic and Alkaline Aqueous Solutions

Authors

  • Franco M. Cabrerizo,

    1. Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas (INIFTA), Universidad Nacional de La Plata, Casilla de Correo 16, Sucursal 4 (1900) La Plata, Argentina
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  • Gabriela Petroselli,

    1. Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas (INIFTA), Universidad Nacional de La Plata, Casilla de Correo 16, Sucursal 4 (1900) La Plata, Argentina
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  • Carolina Lorente,

    1. Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas (INIFTA), Universidad Nacional de La Plata, Casilla de Correo 16, Sucursal 4 (1900) La Plata, Argentina
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  • Alberto L. Capparelli,

    1. Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas (INIFTA), Universidad Nacional de La Plata, Casilla de Correo 16, Sucursal 4 (1900) La Plata, Argentina
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  • Andrés H. Thomas,

    Corresponding author
    1. Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas (INIFTA), Universidad Nacional de La Plata, Casilla de Correo 16, Sucursal 4 (1900) La Plata, Argentina
    • To whom correspondence should be addressed: Lehrstuhl für Umweltmesstechnik, Engler-Bunte-Institut, Universität Karlsruhe, 76128, Karlsruhe, Germany. Fax: +49-721-6086240; e-mail: Esther.Oliveros@ciw.uni-karlsruhe.de

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  • André M. Braun,

    1. Lehrstuhl für Umweltmesstechnik, Engler-Bunte Institüt, Universität Karlsruhe, 76128, Karlsruhe, Germany
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  • Esther Oliveros

    Corresponding author
    1. Lehrstuhl für Umweltmesstechnik, Engler-Bunte Institüt, Universität Karlsruhe, 76128, Karlsruhe, Germany
    • To whom correspondence should be addressed: Lehrstuhl für Umweltmesstechnik, Engler-Bunte-Institut, Universität Karlsruhe, 76128, Karlsruhe, Germany. Fax: +49-721-6086240; e-mail: Esther.Oliveros@ciw.uni-karlsruhe.de

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ABSTRACT

Pterins are heterocyclic compounds with important biological functions, and most of them may exist in two acid-base forms in the pH range between 3 and 13 in aqueous solution. In this work, the photophysical properties of acid and basic forms of six compounds of the pterin family (6-hydroxymethylpterin [HPT], 6-methylpterin [MPT], 6,7-dimethylpterin [DPT], rhamnopterin [RPT], N-methylfolic acid [MFA], and pteroic acid [PA]) have been studied. The effects of the chemical nature of the substituents at position 6 of the pterin moiety and the effects of the pH on the absorption and emission properties are analyzed. The fluorescence characteristics (spectra, quantum yields, lifetimes) of these compounds have been investigated using the single-photon-counting technique. Results obtained for pterin derivatives containing small substituents with 1 carbon atom (HPT, MPT, DPT) and short hydrocarbon chain (4 carbon atoms) (RPT) are different from those found for pterin derivatives containing a p-aminobenzoic acid (PABA) moiety in the substituent (MFA and PA). Fluorescence quantum yields (φF) of the first group of compounds are relatively high (geqslant R: gt-or-equal, slanted0.4), whereas MFA and PA exhibit very small φF values (leqslant R: less-than-or-eq, slant0.01).

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