A New 3,5-Bisporphyrinylpyridine Derivative as a Fluorescent Ratiometric Probe for Zinc Ions

Authors

  • Dr. Nuno M. M. Moura,

    1. Department of Chemistry and QOPNA, University of Aveiro, Campus de Santiago, 3810-193 Aveiro (Portugal)
    2. BIOSCOPE Group, REQUIMTE, Chemistry Department, Faculty of Science and Technology, University NOVA of Lisbon, 2829-516, Monte da Caparica (Portugal)
    3. ProteoMass Scientific Society, Madan Parque, Rua dos Inventores, 2825-182, Caparica (Portugal)
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  • Dr. Cristina Núñez,

    1. BIOSCOPE Group, REQUIMTE, Chemistry Department, Faculty of Science and Technology, University NOVA of Lisbon, 2829-516, Monte da Caparica (Portugal)
    2. ProteoMass Scientific Society, Madan Parque, Rua dos Inventores, 2825-182, Caparica (Portugal)
    3. Department of Geographical and Life Sciences, Canterbury Christ Church University, CT1 1QU Canterbury (UK)
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  • Dr. Sérgio M. Santos,

    1. Department of Chemistry and CICECO, University of Aveiro, 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)
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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)
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  • Dr. Filipe A. Almeida Paz,

    1. Department of Chemistry and CICECO, University of Aveiro, Campus de Santiago, 3810-193 Aveiro (Portugal)
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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)
    • M. Graça P. M. S. Neves, Department of Chemistry and QOPNA, University of Aveiro, Campus de Santiago, 3810-193 Aveiro (Portugal)===

      Carlos Lodeiro, BIOSCOPE Group, REQUIMTE, Chemistry Department, Faculty of Science and Technology, University NOVA of Lisbon, 2829-516, Monte da Caparica (Portugal)===

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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)
    2. ProteoMass Scientific Society, Madan Parque, Rua dos Inventores, 2825-182, Caparica (Portugal)
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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)
    2. ProteoMass Scientific Society, Madan Parque, Rua dos Inventores, 2825-182, Caparica (Portugal)
    • M. Graça P. M. S. Neves, Department of Chemistry and QOPNA, University of Aveiro, Campus de Santiago, 3810-193 Aveiro (Portugal)===

      Carlos Lodeiro, BIOSCOPE Group, REQUIMTE, Chemistry Department, Faculty of Science and Technology, University NOVA of Lisbon, 2829-516, Monte da Caparica (Portugal)===

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Abstract

A new 3,5-disubstituted pyridine with two porphyrin moieties was prepared through an efficient synthetic approach involving 2-formyl-5,10,15,20-tetraphenylporphyrin (1), piperidine, and catalytic amounts of [La(OTf)3]. 3,5-Bis(5,10,15,20-tetraphenylporphyrin-2-ylmethyl)pyridine (2) was fully characterized and its sensing ability towards Zn2+, Cu2+, Hg2+, Cd2+, and Ag+ was evaluated in solution by absorption and fluorescence spectroscopy and in gas phase by using matrix-assisted laser desorption/ionization (MALDI)-TOF mass spectrometry. Strong changes in the ground and excited state were detected in the case of the soft metal ions Zn2+, Cd2+, Hg2+, and Cu2+. A three-metal-per-ligand molar ratio was obtained in all cases and a significant ratiometric behavior was observed in the presence of Zn2+ with the appearance of a new band at 608 nm, which can be assigned to a metal-to-ligand charge transfer. The system was able to quantify 79 ppb of Zn2+ and the theoretical calculations are in accordance with the stoichiometry observed in solution. The gas-phase sensorial ability of compound 2 towards all metal ions was confirmed by using MALDI-TOF MS and in solid state by using polymeric films of polymethylmethacrylate (PMMA) doped with ligand 2. The results showed that compound 2 can be analytically used to develop new colorimetric molecular devices that are able to discriminate between Hg2+ and Zn2+ in solid phase. The crystal structure of ZnII complex of 3,5-bisporphyrinylpyridine was unequivocally elucidated by using single-crystal X-ray diffraction studies.

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