65748-47-2Relevant academic research and scientific papers
Structure and properties of carbonyl-coordinated ruthenium(II) and osmium(II) porphyrin dimers bridged by aza ligands
Bando, Chika,Furukawa, Atsushi,Tsuge, Kiyoshi,Takaishi, Kazumi,Sasaki, Yoichi,Imamura, Taira
experimental part, p. 1955 - 1964 (2009/07/30)
Carbonyl-coordinated ruthenium(II) and osmium(II) porphyrin dimers bridged with aza ligands, [{M(por)-(CO)}2](BL), (M = RuII, Os II; por = ttp (5,10,15,20-tetra-p-tolylporphyrinato dianion), oep (2,3,7,8,12,13,17,18-octa-ethylporphyrinato dianion); BL = pz (pyrazine), bpy (4,4′-bipyridine), dabco (l,4-diazabicyclo[2,2,2]octane)), were prepared and characterized, and their structures were determined by using single-crystal X-ray crystallography. The metal-metal distances of the pz-, bpy-, and dabco-bridged dimers in [{M(por)(CO)}2(BL)] were about 7.1-7.3, 11.5, and 7.3-7.4 A, respectively. From electrochemical measurements, the first oxidation waves of the ruthenium and osmiumporphyrin dimers with the pz and dabco, except the Ru-oep systems, were split, although the first oxidation in the Rucomplexes occurs at the porphyrin rings and in the Os complexes occurs at the metal centers. The extent of the potential splits at the first oxidation processes, which reflects magnitude of the intramolecular redox interactions, was in the orders: ttp > oep and Os (metal oxidation) > Ru (ring oxidation), and dabco ≥ pz ? bpy.
Investigation of the lowest electronic states of osmium(II) tetratolylporphyrins: Photophysics of metalloporphyrin (d,π*) charge transfer states
Gentemann, Steve,Albaneze, Jennifer,Garcia-Ferrer, Ramon,Knapp, Spencer,Potenza, Joseph A.,Schugar, Harvey J.,Holten, Dewey
, p. 281 - 289 (2007/10/02)
The nature of the lowest excited states of a series of osmium(II) porphyrins has been investigated using static and time-resolved emission spectroscopy and ultrafast transient absorption measurements. It is found that a metal-to-ring 3(d,π*) charge transfer excited state is the lowest excited state of the Os(II)P(CO)(L) and Os(II)P(L)2 complexes, where the porphyrin macrocycle (P) is either tetratolyl- or octaethylporphyrin and the axial ligand L is a σ-donor such as pyridine. Previous studies on OsTTP(CO)(py) had led to the assignment of the lowest excited state as the 3(π,π*) state of the porphyrin ring. The results on the Os(II) porphyrins can be contrasted with those found previously for the analogous Ru(II) porphyrins, in which the lowest excited state was found to switch from 3(π,π*) in the RuP(CO)(L) complexes to 3(d,π*) in the RuP(L)2 compounds. The studies further establish the electronic origin of the red- region features in the absorption spectra of metalloporphyrin 3(π,π*) and 3(d,π*) excited states. The combined results demonstrate the critical role played by π-accepting and σ-donating axial ligands in controlling the nature of the lowest excited states, the electronic properties, and excited state dynamics of the biologically-relevant d6 metalloporphyrins.
