title: Evidence for strong mixing between the LC and MLCT excited states in some heteroleptic iridium(III) complexes.
abstract: The synthesis, structure and photophysical properties of series of new luminescent cyclometalated Iridium (III) complexes are reported. The cyclometalated ligand used here is 2-aryl imidazole and the auxiliary ligand is acetyl acetone (acac). The crystal structure of the complex (dmdpi)(2)Ir(acac) (5) show that the Iridium(III) ion resides in a distorted octahedral environment. All complexes exhibit bright photoluminescence (PL) at room temperature and (fpdmdmpi)(2)Ir(acac) 4 has a high solution PL quantum efficiency of 0.56. The role played by electron releasing and electron withdrawing substituents of the 2-arylimidazole ligands towards the stability of HOMO and how the substituent influences the luminescent behaviour are discussed. Furthermore those substituents have effect on the contribution to mixing between (3)(π-π*) and (3)(MLCT) for the lowest excited states.
authors.affiliation: Department of Chemistry, Annamalai University, Annamalainagar 608002, Tamilnadu, India. jtchalam2005@yahoo.co.in
authors.forename: Jayaraman
authors.initials: J
authors.lastname: Jayabharathi
authors.forename: Venugopal
authors.initials: V
authors.lastname: Thanikachalam
authors.forename: Natesan
authors.initials: N
authors.lastname: Srinivasan
authors.forename: Marimuthu Venkatesh
authors.initials: MV
authors.lastname: Perumal