| Autor: |
Ross DAW; Department of Chemistry, University of Otago, P.O. Box 56, Dunedin 9054, New Zealand.; MacDiarmid Institute for Advanced Materials and Nanotechnology, Wellington 6140, New Zealand., Mapley JI; Department of Chemistry, University of Otago, P.O. Box 56, Dunedin 9054, New Zealand.; MacDiarmid Institute for Advanced Materials and Nanotechnology, Wellington 6140, New Zealand., Cording AP; Department of Chemistry, University of Otago, P.O. Box 56, Dunedin 9054, New Zealand., Vasdev RAS; Department of Chemistry, University of Otago, P.O. Box 56, Dunedin 9054, New Zealand.; MacDiarmid Institute for Advanced Materials and Nanotechnology, Wellington 6140, New Zealand., McAdam CJ; Department of Chemistry, University of Otago, P.O. Box 56, Dunedin 9054, New Zealand., Gordon KC; Department of Chemistry, University of Otago, P.O. Box 56, Dunedin 9054, New Zealand.; MacDiarmid Institute for Advanced Materials and Nanotechnology, Wellington 6140, New Zealand., Crowley JD; Department of Chemistry, University of Otago, P.O. Box 56, Dunedin 9054, New Zealand.; MacDiarmid Institute for Advanced Materials and Nanotechnology, Wellington 6140, New Zealand. |
| Abstrakt: |
A 2,2'-bipyridine with bulky triphenylamine substituents in the 6 and 6' positions of the ligand (6,6'-ditriphenylamine-2,2'-bipyridine, 6,6'-diTPAbpy) was generated. Despite the steric bulk, the ligand readily formed bis(homoleptic) complexes with copper(I) and silver(I) ions. Unfortunately, efforts to use the 6,6'-diTPAbpy system to generate heteroleptic [Cu(6,6'-diTPAbpy)(bpy)] + complexes were unsuccessful with only the [Cu(6,6'-diTPAbpy) 2 ](PF 6 ) complex observed. The 6,6'-diTPAbpy ligand could also be reacted with 6-coordinate metal ions that featured small ancillary ligands, namely, the [Re(CO) 3 Cl] and [Ru(CO) 2 Cl 2 ] fragments. While the complexes could be formed in good yields, the steric bulk of the TPA units does alter the coordination geometry. This is most readily seen in the [(6,6'-diTPAbpy)Re(CO) 3 Cl] complex where the Re(I) ion is forced to sit 23° out of the plane formed by the bpy unit. The electrochemical and photophysical properties of the family of compounds were also examined. 6,6'-diTPAbpy exhibits a strong ILCT absorption band (356 nm, 50 mM -1 cm -1 ) which displays a small increase in intensity for the homoleptic complexes ([Cu(6,6'-diTPAbpy) 2 ] + ; 353 nm, 72 mM -1 cm -1 , [Ag(6,6'-diTPAbpy) 2 ] + ; 353 nm, 75 mM -1 cm -1 ), despite containing 2 equiv of the ligand, attributed to an increased dihedral angle between the TPA and bpy moieties. For the 6-coordinate complexes the ILCT band is further decreased in intensity and overlaps with MLCT bands, consistent with a further increased TPA-bpy dihedral angle. Emission from the 1 ILCT state is observed at 436 nm (τ = 4.4 ns) for 6,6'-diTPAbpy and does not shift for the Cu, Ag, and Re complexes, although an additional 3 MLCT emission is observed for [Re(6,6'-diTPAbpy)(CO) 3 Cl] (640 nm, τ = 13.8 ns). No emission was observed for [Ru(6,6'-diTPAbpy)(CO) 2 Cl 2 ]. Transient absorption measurements revealed the population of a 3 ILCT state for the Cu and Ag complexes (τ = 80 ns). All assignments were supported by TD-DFT calculations and resonance Raman spectroscopic measurements. |
