10.1021/jp505619h.s001 Sergey V. Litke Sergey V. Litke Aleksei Yu. Ershov Aleksei Yu. Ershov Thomas J. Meyer Thomas J. Meyer Photophysics of Bis-bipyridyl Nitro Complexes of Ruthenium(II) with Pyridine Ligands: Substituent Effects American Chemical Society 2014 E 00 ligand decay rate constants bi ci emission complex pyridine knr 2014-08-14 00:00:00 Journal contribution https://acs.figshare.com/articles/journal_contribution/Photophysics_of_Bis_bipyridyl_Nitro_Complexes_of_Ruthenium_II_with_Pyridine_Ligands_Substituent_Effects/2264842 Emission, excitation spectra, quantum yields, and emission lifetimes are reported for the mixed ligand, bis-(2,2′-bipyridine)­ruthenium­(II) complexes <i>cis-</i>[Ru­(bpy)<sub>2</sub>(L)­(NO<sub>2</sub>)]<sup>+</sup> with 4-substituted pyridines as ligands L [isonicotinamide (isnc), 4,4′-bipyridine (bipy), pyridine (py), 4-phenylpyridine (phpy), 1,2-bis­(4-pyridyl)­ethane (bpa), 4-picoline (mepy), 4-aminopyridine (apy), and 4-dimethylaminopyridine (ampy)] in EtOH–MeOH, 4:1 (V:V), at 77 K. Radiative, <i>k</i><sub>r</sub>, and nonradiative, <i>k</i><sub>nr</sub>, decay rate constants were determined for the series of complexes, and a linear dependence of ln <i>k</i><sub>nr</sub> on <i>E</i><sub>00</sub>, with <i>E</i><sub>00</sub> as the 0–0 energy gap determined by emission spectral fitting, was obtained with a slope of −(3.35 ± 0.23) × 10<sup>–4</sup> cm<sup>–1</sup>. A linear correlation of <i>E</i><sub>00</sub> for <i>cis</i>-[Ru­(bpy)<sub>2</sub>(L)­(NO<sub>2</sub>)]<sup>+</sup> complexes and Hammett substituent constant σ<sub>p</sub> is found.