Functionalized Porphyrins as Red Fluorescent Probes for Metal Cations: Spectroscopic, MALDI-TOF Spectrometry, and Doped-Polymer Studies

Authors

  • Dr. Nuno M. M. Moura,

    1. Department of Chemistry and QOPNA, University of Aveiro, Campus de Santiago, 3810-193 Aveiro, Portugal, Fax: (+351) 234-370-084
    2. BIOSCOPE Group, REQUIMTE, Chemistry Department, Faculty of Science and Technology, University NOVA of Lisbon, 2829-516, Monte da Caparica, Portugal, Fax: (+351) 212-948-550
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  • Dr. Cristina Nuñez,

    1. BIOSCOPE Group, REQUIMTE, Chemistry Department, Faculty of Science and Technology, University NOVA of Lisbon, 2829-516, Monte da Caparica, Portugal, Fax: (+351) 212-948-550
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  • Dr. Sérgio M. Santos,

    1. Department of Chemistry and CICECO, University of Aveiro, A Campus de Santiago, 3810-193 Aveiro, Portugal
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  • Prof. M. Amparo F. Faustino,

    1. Department of Chemistry and QOPNA, University of Aveiro, Campus de Santiago, 3810-193 Aveiro, Portugal, Fax: (+351) 234-370-084
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  • Prof. José A. S. Cavaleiro,

    1. Department of Chemistry and QOPNA, University of Aveiro, Campus de Santiago, 3810-193 Aveiro, Portugal, Fax: (+351) 234-370-084
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  • Prof. M. Graça P. M. S. Neves,

    Corresponding author
    1. Department of Chemistry and QOPNA, University of Aveiro, Campus de Santiago, 3810-193 Aveiro, Portugal, Fax: (+351) 234-370-084
    • M. Graça P. M. S. Neves, Department of Chemistry and QOPNA, University of Aveiro, Campus de Santiago, 3810-193 Aveiro, Portugal, Fax: (+351) 234-370-084

      Carlos Lodeiro, BIOSCOPE Group, REQUIMTE, Chemistry Department, Faculty of Science and Technology, University NOVA of Lisbon, 2829-516, Monte da Caparica, Portugal, Fax: (+351) 212-948-550

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  • Prof. José Luis Capelo,

    1. BIOSCOPE Group, REQUIMTE, Chemistry Department, Faculty of Science and Technology, University NOVA of Lisbon, 2829-516, Monte da Caparica, Portugal, Fax: (+351) 212-948-550
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  • Prof. Carlos Lodeiro

    Corresponding author
    1. BIOSCOPE Group, REQUIMTE, Chemistry Department, Faculty of Science and Technology, University NOVA of Lisbon, 2829-516, Monte da Caparica, Portugal, Fax: (+351) 212-948-550
    • M. Graça P. M. S. Neves, Department of Chemistry and QOPNA, University of Aveiro, Campus de Santiago, 3810-193 Aveiro, Portugal, Fax: (+351) 234-370-084

      Carlos Lodeiro, BIOSCOPE Group, REQUIMTE, Chemistry Department, Faculty of Science and Technology, University NOVA of Lisbon, 2829-516, Monte da Caparica, Portugal, Fax: (+351) 212-948-550

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  • MALDI-TOF=matrix-assisted laser desorption/ionization time-of-flight.

Abstract

The sensing ability of benzoporphyrins 15 and porphyrin-2-ylpyridines 610 towards different metal ions Na+, K+, Ca2+, Mg2+, Pb2+, Cu2+, Ni2+, Zn2+, Cd2+, Hg2+, and Cr3+ was explored in solution by absorption and fluorescence spectroscopy. Strong changes in the ground and excited state were detected only in the case of the soft metal ions Zn2+, Cd2+, Hg2+, and Cu2+. A one metal per ligand molar ratio was obtained in all cases for compounds 15. In addition, a remarkable increase of the emission intensity for 15 was observed in the presence of Hg2+. In this series the highest association constant was obtained for compound 1 (log Kass=(8.71±4.81)×10−3), which was able to quantify 32 ppb of Hg2+. For compounds 610 containing an additional pyridine unit, a metal-to-ligand stoichiometry of 1:2 was determined. The gas-phase detection abilities of compounds 110 using MALDI-TOF-MS spectrometry confirmed that their sensorial ability and theoretical calculations are in accordance with the stoichiometry observed. Our preliminary studies show that some of the compounds supported in polymethylmethacrylate (PMMA) films can be used as promising metal-ion solid chemosensors; it was found that compound 1 in PMMA is able to distinguish between Zn2+ and Hg2+ in the solid phase.

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