126614-54-8Relevant articles and documents
Cross-couplings in the elaboration of luminescent bis-terpyridyl iridium complexes: The effect of extended or inhibited conjugation on emission
Leslie, Wendy,Batsanov, Andrei S.,Howard, Judith A.K.,Williams, J.A. Gareth
, p. 623 - 631 (2004)
The utility of Suzuki cross-coupling methodology for the in situ elaboration of bromo-functionalised bis-terpyridyl iridium(III) complexes has been explored. The complex [Ir(tpy)(tpy-φ-Br)]3+ {tpy-φ-Br = 4′-(4-bromophenyl)-2,2′:6′,2″-terpyridine} undergoes palladium-catalysed cross-coupling with aryl boronic acids to yield biaryl-substituted complexes directly. The biphenyl and 4-cyanobiphenyl-substituted products display relatively intense, long-lived (τ > 100 μs) yellow emission in degassed aqueous solution at room temperature, assigned to a 3π-π* state. A 4-aminobiphenyl-substituted analogue displays an additional low energy absorbance band, attributed to an intraligand charge-transfer (ILCT) excited state, and is scarcely emissive under the same conditions. The iridium(III) complex of 4′-mesityl-terpyridine is also reported. Its emission is much shorter-lived, with a spectral profile resembling that of unsubstituted [Ir(tpy)2]3-, confirming the need for the attainment of a roughly coplanar geometry for stabilisation of the 3π-π* excited state.
