title: The interaction of Hg(2+) and trivalent ions with two new fluorescein bio-inspired dual colorimetric/fluorimetric probes.
abstract: Two new luminescent compounds containing fluorescein-amino acid units have been designed and synthesized via an ester linkage between a fluorescein ethyl ester and Boc-Ser(TBDMS)-OH or Boc-Cys(4-MeBzl)-OH, and their photophysical properties have been explored. The optical response of both compounds (2 and 3) towards the metal ions Na(+), K(+), Hg(+), Ag(+), Ca(2+), Co(2+), Ni(2+), Cu(2+), Zn(2+), Cd(2+), Pb(2+), Hg(2+), Al(3+), Fe(3+), Ga(3+)and Cr(3+) was investigated in pure acetonitrile and in acetonitrile/water mixtures. A strong CHEF (Chelation-Enhanced Fluorescence) effect was observed with all the trivalent metals and Hg(2+) ions in both solvents. UV-vis absorption, steady state and time resolved emission spectroscopy methods were employed. The results show the formation of mononuclear complexes with Al(3+), Fe(3+), Ga(3+), Cr(3+), and Hg(2+). Theoretical calculation using Density Functional Theory was performed in order to obtain atomistic insights into the coordination geometry of Al(3+) and Hg(2+) to the fluorescein 3, which is in accordance with the experimental stoichiometry results obtained in the Job's plot method. Among the active cations, the minimum detectable amount is under 1 μM for most of the cases in both absorption and fluorescence spectroscopy methods.
authors.affiliation: Instituto de Química, Universidade de São Paulo, Av. Prof. Lineu Prestes, 748, CxP. 26077, São Paulo, 05508-000, Brazil. alcindo@iq.usp.br.
authors.forename: A C
authors.initials: AC
authors.lastname: Gonçalves
authors.forename: V
authors.initials: V
authors.lastname: Pilla
authors.forename: E
authors.initials: E
authors.lastname: Oliveira
authors.forename: S M
authors.initials: SM
authors.lastname: Santos
authors.forename: J L
authors.initials: JL
authors.lastname: Capelo
authors.forename: A A
authors.initials: AA
authors.lastname: Dos Santos
authors.forename: C
authors.initials: C
authors.lastname: Lodeiro
mesh_terms: D000097:Acetonitriles / Q000737:chemistry; D000596:Amino Acids / Q000737:chemistry; D001565:Benzoates / Q000138:chemical synthesis / Q000737:chemistry*; D002614:Chelating Agents / Q000737:chemistry; D003124:Colorimetry / Q000379:methods; D056831:Coordination Complexes / Q000737:chemistry; D019793:Fluorescein / Q000737:chemistry*; D005456:Fluorescent Dyes / Q000138:chemical synthesis / Q000737:chemistry*; D007477:Ions / Q000032:analysis; D057230:Limit of Detection; D008628:Mercury / Q000032:analysis*; D013050:Spectrometry, Fluorescence / Q000379:methods; D014867:Water / Q000737:chemistry
chemical_list: D000097:Acetonitriles; D000596:Amino Acids; D001565:Benzoates; D002614:Chelating Agents; D056831:Coordination Complexes; D005456:Fluorescent Dyes; D007477:Ions; D014867:Water; D008628:Mercury; D019793:Fluorescein