Long-lived higher excited state luminescence from new ruthenium(II)–allenylidene complexes

Abstract

Resonance Raman spectra of heteroatom substituted ruthenium(II)-allenylidene complexes, obtained by irradiation into the second electronic absorption band, clearly prove the d(Ru)-> 1t*(CCC) MLCT character of the corresponding electronic transition. The complexes are not significantly luminescent at room temperature, but in solvent glasses at 77 K, emission is observed. Only some of the complexes studied are luminescent upon irradiation into their lowest-energy absorption band. The striking finding of this study is that a lmost a ll complexes are luminescent on irrad iation into their second absorption band. The emission was shown to originate from a higher lying 3MLCT state, which shows that internal conversion to the lowest excited state is very inefficient in these complexes.

Synthesis, Characterization, and Electrochemical Behavior of Mono- and Bimetallic Ruthenium and Rhenium Allenylidenes Bearing Multiconjugated Organic Spacers

“…According to DFT calculations on model [(CO) 5 M(C) n H 2 ] ( n = 2, 9) complexes, the two low-energy bands are assigned to the geometrically permitted LUMO ← HOMO−1 transition (λ max = 504 nm) and to the geometrically forbidden weak LUMO ← HOMO transition (λ max = 850 nm), respectively. On the basis of the electrochemical results and on earlier theoretical calculations, the LUMO ← HOMO transition could be described as a MLCT from a dπ metal orbital to π* orbital of the ligand . Both transitions display a bathocromic shift with respect to the related Ru(II) cumulenes [Cl(PR 3 ) 4 Ru(C) n R 2 ] + , where the weak peak is detected around 600 nm, while the main absorption band is around 400 nm. ,, Such a shift is likely due to the presence of the aromatic terminal groups in 5 , which strengthen the cumulene conjugation responsible for the red shift .…”

Lanthanide Sensitization with Ruthenium Carbon-Rich Complexes and Redox Commutation of Near-IR Luminescence

“…Note that, as expected, identical NIR emission spectra are obtained upon excitation in the TTA absorption band (λ exc 360 nm). In contrast to the case for 1Yb , the allenylidene compound [4Yb]OTf displays a very weak emission, suggesting that Ru–allenylidene moieties are less efficient antennas than the acetylide complexes (Figure ) …”

Platinum(II) and Gold(III) Allenylidene Complexes: Phosphorescence, Self‐Assembled Nanostructures and Cytotoxicity

“…Although a variety of [L n MCCC(R′)R′′] complexes, in which M is metal ion of Cr, W, Mn, Ru, Os, Ir, Ag, Pd or Pt, have been prepared,4, 7 only two types of allenylidene complexes have been reported to display phosphorescence. Slageren and co‐workers reported that [Cl(dppm) 2 RuCCC(R′)R′′] complexes are emissive in glassy solutions at 93 K 8. Nazeeruddin and co‐workers claimed [(ppy) 2 (Ph 3 P)IrCCC(OMe)N(CH 2 ) 4 ] + to be the first allenylidene complex that emits in fluid solutions (with an emission quantum yield of 2.9 % and a lifetime of 465 ns) 9.…”