Premium
Fluorescent Sensors for Transition Metals Based on Electron‐Transfer and Energy‐Transfer Mechanisms
Author(s) -
Fabbrizzi Luigi,
Licchelli Maurizio,
Pallavicini Piersandro,
Perotti Angelo,
Taglietti Angelo,
Sacchi Donata
Publication year - 1996
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.19960020114
Subject(s) - anthracene , chemistry , quenching (fluorescence) , fluorescence , electron transfer , metal ions in aqueous solution , photochemistry , fluorophore , metal , supramolecular chemistry , photoinduced electron transfer , titration , cyclam , ligand (biochemistry) , inorganic chemistry , molecule , organic chemistry , receptor , biochemistry , physics , quantum mechanics
Fluorescent sensors for 3d divalent metal ions have been designed by means of a supramolecular approach: an anthracene fragment (the signalling subunit) has been linked to either a cyclic or a noncyclic quadridentate ligand (the receptor). Occurrence of the metal‐receptor interaction is signalled through the quenching of anthracene fluorescence. When the receptor (i.e., the dioxotetramine subunit of sensors 2 and 3 ) is able to promote the one‐electron oxidation of the metal, quenching takes place through a photoinduced metal‐to‐fluorophore electron‐transfer mechanism. In the case of sensors containing a tetraamine binding subunit ( 4 and 5 ), quenching proceeds by an energy‐transfer process. Selective metal binding and recognition can be achieved by varying the pH, and metal ions can be distinguished (e.g., Cu II from Ni II ) by spectrofluorimetric titration experiments in buffered solutions. Whereas systems 2, 3 and 5 show reversible metal binding behaviour, the cyclam ‐containing system 4 irreversibly incorporates transition metals (due to the kinetic macrocyclic effect ) and cannot work properly as a sensor.