Synthesis and H+, Cu2+, and Zn2+ coordination behavior of a bis(fluorophoric) bibrachial lariat aza-crown

M. Paz Clares, Juan Aguilar, Ricardo Aucejo, Carlos Lodeiro, M. Teresa Albelda, Fernando Pina, J. C. Lima, A. Jorge Parola, João Pina, J. Seixas de Melo, Concepción Soriano, Enrique García-España

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52 Citations (Scopus)

Abstract

The synthesis, protonation behavior, and Cu2+ and Zn 2+ coordination chemistry of the novel bibrachial aza lariat ether (naphthalen-1-ylmethyl)[2-(20-{2-[(naphthalen-1-ylmethyl)amino]ethyl}-3,6,9,17, 20,23,29,30-octaazatricyclo-[23.3.1.1*11,15*]triaconta-1(29),11(30), 12,14,25,27-hexaen-6-yl)ethyl]amine (L) are discussed. The macrocycle, which has two aminoethyl naphthyl moieties symmetrically appended to a 2:2 azapyridinophane structure, displays, in the pH range 2-11, six protonation steps that correspond to the protonation of the secondary amino groups. Steady-state fluorescence measurements show emissions due to the monomer and to the excimer formed between the two naphthalene fragments of the macrocycle. The time-resolved fluorescence data, obtained by the time-correlated single photon counting technique, show that a significant percentage of excimer is preformed as ground-state dimers. The ligand L forms with the metal ions Cu2+ and Zn2+ mono- and dinuclear complexes in aqueous solution. The influence of metal coordination in the fluorescence emission of L is analyzed. The acid-base, coordination capabilities, and emissive behavior of L are compared with those presented by its synthetic precursor L1, which has a tripodal tris(2-aminoethyl)amine structure functionalized at one of its terminal amino groups with a naphthyl moiety.

Original languageEnglish
Pages (from-to)6114-6122
Number of pages9
JournalInorganic Chemistry
Volume43
Issue number19
DOIs
Publication statusPublished - 20 Sep 2004

Keywords

  • Molecules
  • Ligands
  • Stability constants

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