The interaction of Hg2+ and trivalent ions with two new fluorescein bio-inspired dual colorimetric/fluorimetric probes


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+, Ca2+, Co2+, Ni2+, Cu2+, Zn2+, Cd2+, Pb2+, Hg2+, Al3+, Fe3+, Ga3+ and Cr3+ 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 Hg2+ 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 Al3+, Fe3+, Ga3+, Cr3+, and Hg2+. Theoretical calculation using Density Functional Theory was performed in order to obtain atomistic insights into the coordination geometry of Al3+ and Hg2+ 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 mu M for most of the cases in both absorption and fluorescence spectroscopy methods.






Goncalves, AC; Pilla, V; Oliveira, E; Santos, SM; Capelo, JL; Dos Santos, AA; Lodeiro, C

nossos autores


E. Oliveira acknowledges the post-doctoral grant from Fundacao para a Ciencia e a Tecnologia (FCT-MEC) (Portugal) SFRH/BPD/72557/2010. A Goncalves and V. Pilla thank CNPQ/Brazil for the PhD and post-doctoral (202553/2014-0) grant respectively. C. Lodeiro thanks the CNPQ program, Science without borders 2014-2016 grant (Brazil). Financial support from the Scientific PROTEOMASS Association (Portugal), the University of Sao Paulo through the NAP-CatSinQ (Research Core in Catalysis and Chemical Synthesis), FAPESP, CAPES and FAPEMIG (Brazil) (APQ-00360-14) is acknowledged. This work was supported by the Unidade de Ciencias Biomoleculares Aplicadas-UCIBIO which is financed by national funds from FCT/MEC (UID/Multi/04378/2013) and co-financed by the ERDF under the PT2020 Partnership Agreement (POCI-01-0145-FEDER-007728). Part of this work was developed within the scope of the project CICECO-Aveiro Institute of Materials, POCI-01-0145-FEDER-007679 (FCT Ref. UID/CTM/50011/2013), financed by national funds through the FCT/MEC and when appropriate co-financed by FEDER under the PT2020 Partnership Agreement. S. M. S. thanks FCT for the FCT Investigator starting grant IF/00973/2014.

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