Photoinduced intramolecular energy transfer in covalently linked chromophore-quencher ruthenium(II) complexes

✍ Scribed by Gaetano Giuffrida; Giovanni Guglielmo; Vittorio Ricevuto; Sebastiano Campagna

• Publisher: Elsevier Science
• Year: 1991
• Tongue: English
• Weight: 523 KB
• Volume: 180
• Category: Article
• ISSN: 0009-2614
• DOI: 10.1016/0009-2614(91)87111-n

✦ Synopsis

Two novel covalently linked chromophore-quencher ruthenium(U) complexes, Ru(bpy),(py-N=CH-An):+ (2; bpy=2,2'bipyridine; py-N=CH-An=C[ (9-anthryl)methyl]imino-pyridine)

and Ru(bpy),(py-NH-CH2-An):+ (3; py-NH-CH,-An=4-[ (9-anthryl)methyl]amino-pyridine), along with the "reference" complex Ru(bpy)z(py-NHZ):f

(1; py-NH,=Caminopyridine), have been studied. Excitation into the RuAbpy charge-transfer manifold is followed in 2 and 3 by fast intramolecular energy transfer to the lowest triplet excited state of an anthryl group. For 2, the luminescence quantum yield is quenched more effectively than the luminescence lifetime. Such a behavior is accounted for when one considers the possibility of 2 to exist in a number of conformers. The nature of the connectors plays a key role in determining the extent of the intramolecular process: actually, only a partial quenching occurs in the semi-rigid molecule 2, while the quenching is complete in 3.