Four mononuclear Cu(I) complexes were prepared, described as [Cu(N,N)2]PF6 (1) and [Cu(N,N)(P,P)]PF6 (2-4), where N,N is N-(1-(2H-indazol-2-yl)ethylidene)-2,6-diisopropylaniline and P,P are phosphine derived ancillary ligands (bis[2-(diphenylphosphino)phenyl]ether (POP), bis(diphenylphosphino)ethane (dppe) or 2 PPh3). These new species were characterized by NMR, FT-IR, elemental analyses, cyclic voltammetry, UV-Vis – emission spectroscopy, transient absorption spectroscopy and DFT calculations. In addition, complexes 1 and 2 were characterized by X-ray diffraction. The four complexes showed an MLCT absorption band between 400-450 nm, in addition to a weak structured phosphorescence in a 4:1 ethanol:methanol glassy matrix at 77 K. Complexes 2-4 have emission profiles that resemble the phosphorescence of the protonated N,N ligand, suggesting a triplet LC character of the lowest lying excited state at 77 K. By contrast, a mixed MLCT/LC triplet emission is most likely responsible for the phosphorescence in complex 1. Weak ligand-centered emission is also detected in the solid state at room temperature but only in the case of complexes 2 and 4, suggesting thermally activated deactivation processes in the case of 1 and 3. Notably, the transient absorption spectroscopy of complexes 2-4 in CH2Cl2 solution confirms a strong contribution from a ligand-centered (LC) triplet excited state, pointing towards a mixed 3MLCT/3LC character of the transient species in solution at room temperature, undergoing a non-radiative deactivation in the s time-scale. This behavior markedly differs from that observed for complex 1, whose short-lived 3MLCT excited state is followed by ultrafast transient absorption spectroscopy.
Synthesis of New Phosphorescent Imidoyl-Indazol and Phosphine Mixed Ligand Cu(I) Complexes – Structural Characterization and Photophysical Processes
NATALI, Mirco;
2016
Abstract
Four mononuclear Cu(I) complexes were prepared, described as [Cu(N,N)2]PF6 (1) and [Cu(N,N)(P,P)]PF6 (2-4), where N,N is N-(1-(2H-indazol-2-yl)ethylidene)-2,6-diisopropylaniline and P,P are phosphine derived ancillary ligands (bis[2-(diphenylphosphino)phenyl]ether (POP), bis(diphenylphosphino)ethane (dppe) or 2 PPh3). These new species were characterized by NMR, FT-IR, elemental analyses, cyclic voltammetry, UV-Vis – emission spectroscopy, transient absorption spectroscopy and DFT calculations. In addition, complexes 1 and 2 were characterized by X-ray diffraction. The four complexes showed an MLCT absorption band between 400-450 nm, in addition to a weak structured phosphorescence in a 4:1 ethanol:methanol glassy matrix at 77 K. Complexes 2-4 have emission profiles that resemble the phosphorescence of the protonated N,N ligand, suggesting a triplet LC character of the lowest lying excited state at 77 K. By contrast, a mixed MLCT/LC triplet emission is most likely responsible for the phosphorescence in complex 1. Weak ligand-centered emission is also detected in the solid state at room temperature but only in the case of complexes 2 and 4, suggesting thermally activated deactivation processes in the case of 1 and 3. Notably, the transient absorption spectroscopy of complexes 2-4 in CH2Cl2 solution confirms a strong contribution from a ligand-centered (LC) triplet excited state, pointing towards a mixed 3MLCT/3LC character of the transient species in solution at room temperature, undergoing a non-radiative deactivation in the s time-scale. This behavior markedly differs from that observed for complex 1, whose short-lived 3MLCT excited state is followed by ultrafast transient absorption spectroscopy.I documenti in SFERA sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
