Luminescent chiral ionic Ir(III) complexes: Synthesis and photophysical properties

Three homologous series of luminescent octahedral ionic Ir(III) complexes (1-12) with a dual stereogenic center of general formulaΔ,Λ (R,S)[(ppy)2Ir(R-campy)]X, where ppy=2-phenylpyridine, R-campy=2-methyl-5,6,7,8-tetrahydroquinolin-8-amine (Me-campy) or 8-amino-5,6,7,8-tetrahydroquinolines (H-campy) and as counterions X-=Cl-or CH3COO-have been synthesized and characterized. The NMR characterization of each complex highlighted the diastereoisomeric purity and the absolute configuration has been confirmed by Electronic Circular Dichroism spectroscopy. The absorption and the luminescence properties of the compounds in solution and in solid state have been investigated by UV-vis, steady-state emission and time-correlated single-photon counting spectroscopy. The obtained results from the 12 compounds highlight the difficult to correlate photophysical properties in solution to the stereochemistry, while excited states decay studies of the solid state samples indicate a correlation between photophysics and packing mode which is affected by the different stereochemistry.