Dual emissions in the solution phase photoluminescence of rhodium(III) complexes. Ligand field fluorescence from a heavy metal complex?

From curiosity to applications. A personal perspective on inorganic photochemistry

“… 18 These observations, combined with early sensitization experiments, 24 led to the conclusion that initial LF excitation to form 1 MC* states was followed by efficient internal conversion/intersystem crossing to the lowest energy 3 MC* state ( i.e. the 3 T 1 ) 25 from which emission or reaction largely occurred (note: k ISC values > 5 × 10 9 s –1 have been measured for Rh( iii ) ammine complexes). 25 This progression is envisioned by the Jablonski diagram shown in Fig.…”

“…the 3 T 1 ) 25 from which emission or reaction largely occurred (note: k ISC values > 5 × 10 9 s –1 have been measured for Rh( iii ) ammine complexes). 25 This progression is envisioned by the Jablonski diagram shown in Fig. 6 .…”

Metal centered ligand field excited states: Their roles in the design and performance of transition metal based photochemical molecular devices

“…ISC rate constants, k ISC , have been determined to be >5 × 10 9 s −1 for a series of Rh(NH 3 ) 5 X 2+ and Rh(NH 3 ) 4 X 2 + complexes [119], and ∼5 × 10 11 s −1 for cisRhX 2 (bpy) 2 + complexes [120], (where X = Br − and Cl − for both studies). The nested nature of the LF ES singlet and triplet surfaces (with respect to each other) for Rh(III) complexes suggests that the internal conversion/intersystem crossing processes would be expected to occur through a weak-coupling mechanism.…”

Fluorescence in Rhoda- and Iridacyclopentadienes Neglecting the Spin–Orbit Coupling of the Heavy Atom: The Ligand Dominates

“…It soon became clear from the early works of Balzani and co-workers on the prototypical compound [Ru(bpy) 3 ] 2+ and its derivatives that the combination of heavy metals exhibiting exceptionally high intrinsic SOC with a variety of different ligands allows facile tuning of the excited states. , As a consequence, fast ISC occurs, quenching the fluorescence from S 1 , and highly efficient radiative decay from the T 1 state (phosphorescence) with quantum yields (Φ p ) of up to unity can be observed. , A large number of phosphorescent transition-metal compounds mainly based on Ru (ξ = 1259 cm –1 ), Re (ξ = 2200 cm –1 ), Os (ξ = 3500 cm –1 ), Ir (ξ = 3909 cm –1 ), or Pt (ξ = 4000 cm –1 ) with bipyridine, 2-phenylpyridine, phenyltriazolate, or phenyltetrazolate ligands have been synthesized. ,,,,,− Their excited states are usually described as metal-to-ligand charge transfer (MLCT), ligand-to-ligand charge transfer (LLCT), or intraligand charge transfer (ILCT) states or mixtures thereof. Only a few of those compounds show residual fluorescence (fluorescence quantum yield Φ f < 1%), the low efficiency of which is attributed to the fast ISC. ,− In fact, ultrafast conversion of the S 1 state to the T n states on the time scale of vibrations (i.e., a few femtoseconds) was found by the groups of Chergui and McCusker. ,− They carried out picosecond flash spectroscopy on bipyridyl complexes of Fe, Ru, and Re in order to elucidate the time dependence of the ISC processes on the nature of the transition metal present. Surprisingly, the iron and ruthenium bipyridyl complexes exhibited the fastest intersystem crossing (ca.…”