Photophysics of mixed ligand complexes of ruthenium(II) with 2,2′-bipyridyl and phosphines

Luminescent ruthenium–polypyridine complexes & phosphorus ligands: anything but a simple story

“…5). 30 Compared to the corresponding Ru(bpy) 2 X 2 complexes, the replacement of one bipyridine by a diphosphine ligand is accompanied by a hypsochromic shift of l abs and l em , in agreement with the ligand field theory. This effect is much more pronounced for l em of 23a (À44 nm) than for 23b (À11 nm), and hydrogen bonding between the nitro ligands and the alcoholic solvent has been invoked to explain this phenomenon.…”

“…2). 30 The replacement of an X-type anionic ligand by a phosphine is followed by a hypsochromic shift of l abs and l em and a two-to threefold increase in the luminescence lifetime of the complex, illustrating an increase in the energy of the MLCT excited state. An extension of this discussion to similar Ru(bpy)P 2 X 2 complexes is presented later in the mono(bipyridine) complexes section.…”

“…This effect is much more pronounced for l em of 23a (À44 nm) than for 23b (À11 nm), and hydrogen bonding between the nitro ligands and the alcoholic solvent has been invoked to explain this phenomenon. 30,41 Examination of the shape of the emission bands yields additional information: as for complex 22, 21b the relatively high intensities of the 0-1 and 0-2 transitions, compared to the 0-0 transition, indicate a higher degree of distortion in the MLCT excited state of 23a/b, and overall give rise to a broad emission band with no vibrational structure, contrary to Ru(bpy) 2 X 2 . Consistently, larger Stokes shifts are observed for 23a/b than for Ru(bpy) 2 X 2 .…”

Spectroscopy of highly luminescent 1,3,5-triazapentadiene complexes of platinum(II) in solution and in the adsorbed and solid states and quantum-chemical interpretation

“…Luminescence quantum yields (ϕ) of complexes were determined on a setup [3] with an integrating sphere, which was covered by a fresh MgO layer, and the intensities of luminescence and scattered light were simultaneously measured via two independent measuring channels. As a reference sample, we used a standard solution of Na fluorescein with a known quantum yield.…”

“…It is known that the lumi nescence decay kinetics of adsorbates is rather compli cated due to the essentially different adsorptive inter action with the surface, which is described by models of the polyexponential decay [3,13,14]. However, the similar biexponential luminescence decay at 300 K and the monoexponential decay at a low (77 K) tem perature of polycrystals of complexes, as well as of their solution in the polymer matrix, confirms the aforesaid assumption that there occur two emitting states within the same molecule and that one of them can be thermally activated at room temperature.…”