Fluorescence Redox Switching Systems Operating through Metal Centres: the NiIII/NiII Couple

✍ Scribed by Prof. Dr. Luigi Fabbrizzi; Dr. Maurizio Licchelli; Dr. Giancarlo De Santis; Dr. Nicola Sardone; Aldo Hendrikus Velders

• Publisher: John Wiley and Sons
• Year: 1996
• Tongue: English
• Weight: 841 KB
• Volume: 2
• Category: Article
• ISSN: 0947-6539
• DOI: 10.1002/chem.19960021010

✦ Synopsis

The covalently linked two-component systems 3 and 4 display fluorescence redox switching activity: the Ni"' form quenches the fluorescence of the proximate aromatic fluorophore, whereas the Ni" form does not. Thus, fluorescence can be switched on and off at will through the reversible Ni"/Ni"' 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-Ni"' 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 Nil' and Ni"' forms (an OFF/OFF situation), through an energy transfer mechanism. The crystal and molecular structure of 4 in its protonated form is also described.