American Chemical Society
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Luminescence of Ruthenium Halide Complexes Containing a Hemilabile Phosphine Pyrenyl Ether Ligand

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journal contribution
posted on 2006-06-12, 00:00 authored by Kristin M. Matkovich, Lisa M. Thorne, Michael O. Wolf, Tamara C. S. Pace, Cornelia Bohne, Brian O. Patrick
A series of Ru(II) complexes, tcc-RuX2(POC4Pyr-P,O)2 (X = Cl (3), Br (4), I (5)), containing the hemilabile phosphine pyrenyl ether ligand 4-{2-(diphenylphosphino)phenoxy}butylpyrene (POC4Pyr (1)) are reported. The synthesis and spectroscopic properties of both the ligand, POC4pyr (1), and ligand oxide, P(O)OC4pyr (2), and the solid-state structure of 1 are reported. Complexes 35 react rapidly with CO to give complexes ttt-RuX2(CO)2(POC4pyr-P)2 (X = Cl (6), Br (7), I (8)). No pyrene excimer emission is detected from 35; however, different intensities of excimer emission are observed for 68. The intensity of excimer emission decreases through the series, with 6 showing the most intense response. The emission is solely due to intramolecular pyrene excimers at low concentrations (≤10-4 M). Comparison of the UV−vis and steady-state fluorescence spectra shows overlap between the low energy d−d absorption of 7 and 8 with excimer emission (480 nm), suggesting nonradiative energy transfer may be occurring. Once excess CO is removed, complexes 68 isomerize to cis-dicarbonyl complexes cct-RuX2(CO)2(POC4Pyr-P)2 (X = Cl (9), Br (10), I (11)). The intensity of excimer emission from 911 increases with respect to the excimer emission observed for 68, with 9 showing a significant increase in excimer intensity.