Synthesis, separation, and circularly polarized luminescence studies of enantiomers of iridium(III) luminophores

Abstract

A family of heteroleptic (C∧N)2Ir(acac) and homoleptic fac-Ir(C∧N)3 complexes have been synthesized and their photophysical properties studied (where C∧N = a substituted 2-phenylpyridine and acac = acetylacetonate). The neutral Δ and ∧ complexes were separated with greater than 95% enantiomeric purity by chiral supercritical fluid chromatography, and the solution circular dichroism and circularly polarized luminescence spectra for each of the enantio-enriched iridium complexes were obtained. The experimentally measured emission dissymmetries (gem) for this series compared well with predicted values provided by time-dependent density functional theory calculations. The discovered trend further showed a correlation with the dissymmetries of ionic, enantiopure hemicage compounds of Ru(II) and Zn(II), thus demonstrating the applicability of the model for predicting emission dissymmetry values across a wide range of complexes. © 2008 American Chemical Society.