title: Iridium(III) complexes with sulfonyl and fluorine substituents: synthesis, stereochemistry and effect of functionalisation on their photophysical properties.
abstract: The synthesis and photophysical and electrochemical characterisation of new heteroleptic iridium complexes with electron-withdrawing sulfonyl groups and fluorine atoms bound to phenylpyridine ligands are reported. The emission energy of these materials strongly depends on the position of the sulfonyl groups and on the number of fluorine substituents. A 90 nm wide tuning range of photoluminescence from the blue-green (lambda(em)=468 nm) of iridium(III)bis[2-(4'-benzylsulfonyl)phenylpyridinato-N,C2'][3-(pentafluorophenyl)-pyridin-2-yl-1,2,4-triazolate] to the orange (lambda(em)=558 nm) of iridium(III)bis[2-(3'-benzylsulfonyl)phenylpyridinato-N,C2'](2,4-decanedionate) has been achieved. Emission quantum yields ranging from 47 to 71% have also been found for degassed solutions of the complexes, and a surprisingly high value of 16% was recorded for iridium(III)bis[2-(5'-benzylsulfonyl-3',6'-difluoro)phenylpyridinato-N,C2'](2,4-decanedionate) in air-equilibrated dichloromethane. A unusual stereochemistry of the benzylsulfonyl-substituted dimer and heteroleptic complexes has been detected by (1)H NMR spectroscopy, and is characterised by the mutual cis disposition of the pyridyl nitrogen atoms of the phenylpyridine ligands, which differs from the most common trans arrangement reported in the literature.
authors.affiliation: Dipartimento di Chimica, Università degli Studi di Bari via Orabona 4, 70126 Bari, Italy.
authors.forename: Roberta
authors.initials: R
authors.lastname: Ragni
authors.forename: Enrico
authors.initials: E
authors.lastname: Orselli
authors.forename: Gregg S
authors.initials: GS
authors.lastname: Kottas
authors.forename: Omar Hassan
authors.initials: OH
authors.lastname: Omar
authors.forename: Francesco
authors.initials: F
authors.lastname: Babudri
authors.forename: Adriana
authors.initials: A
authors.lastname: Pedone
authors.forename: Francesco
authors.initials: F
authors.lastname: Naso
authors.forename: Gianluca M
authors.initials: GM
authors.lastname: Farinola
authors.forename: Luisa
authors.initials: L
authors.lastname: De Cola