The covalently linked two-component systems 3 and 4 display fluorescence redox switching activity: the NiIII form quenches the fluorescence of the proximate aromatic fluorophore, whereas the NiII form does not. Thus, fluorescence can be switched on and off at will through the reversible NiII/NiIII redox reaction, which is carried out both electrochemically (in MeCN) and chemically (in EtOH). Quenching of the excited fluorophore F* is ascribed to a thermodynamically favoured F*-to-NiIII electron transfer mechanism. The more flexible system 5 does not work as a switch, since the fluorescence of the anthracene subunit is quenched in both NilII and NiIII forms (an OFF/OFF situation), through an energy transfer mechanism. The crystal and molecular structure of 4 in its protonated form is also described.
Fluorescence Redox Switching Systems Operating through Metal Centres: the NiIII/NiII Couple
FABBRIZZI, LUIGI;LICCHELLI, MAURIZIO;
1996-01-01
Abstract
The covalently linked two-component systems 3 and 4 display fluorescence redox switching activity: the NiIII form quenches the fluorescence of the proximate aromatic fluorophore, whereas the NiII form does not. Thus, fluorescence can be switched on and off at will through the reversible NiII/NiIII redox reaction, which is carried out both electrochemically (in MeCN) and chemically (in EtOH). Quenching of the excited fluorophore F* is ascribed to a thermodynamically favoured F*-to-NiIII electron transfer mechanism. The more flexible system 5 does not work as a switch, since the fluorescence of the anthracene subunit is quenched in both NilII and NiIII forms (an OFF/OFF situation), through an energy transfer mechanism. The crystal and molecular structure of 4 in its protonated form is also described.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
