| 1. |
- Karlsson, Susanne, et al.
(author)
-
How Close Can You Get? : Studies of Ultrafast Light-Induced Processes in Ruthenium-[60] Fullerene Dyads with Short Pyrazolino and Pyrrolidino Links
- 2008
-
In: Inorganic Chemistry. - : American Chemical Society (ACS). - 0020-1669 .- 1520-510X. ; 47:16, s. 7286-7294
-
Journal article (peer-reviewed)abstract
- Two pyrazoline- and one pyrrolidine-bridged Ru(II)bipyridine-[60]fullerene dyads have been prepared and studied by ultrafast time-resolved spectroscopy. A silver-assisted synthesis route, in which Ag(I) removes the chlorides from the precursor complex Ru(bpy)(2)Cl-2 facilitates successful coordination of the [60]fullerene-substituted third ligand. Upon light excitation of the ruthenium moiety, the emission was strongly quenched by the fullerene. The main quenching mechanism is an exceptionally fast direct energy transfer (k(obs) > , 1 x 10(12) s(-1) in the pyrazoline-bridged dyads), resulting in population of the lowest excited triplet state of fullerene. No evidence for electron transfer was found, despite the extraordinarily short donor-acceptor distance that could kinetically favor that process. The observations have implications on the ongoing development of devices built from Ru-polypyridyl complexes and nanostructured carbon, such as C-60 or nanotubes.
|
|
| 2. |
|
|
| 3. |
|
|
| 4. |
- Modin, Judit, et al.
(author)
-
New Pyrazolino- and Pyrrolidino[60]fullerenes with Transition-Metal Chelating Pyridine Substitutents: Synthesis and Complexation to Ru(II)
- 2005
-
In: Organic Letters. ; 7:18, s. 3977-3979
-
Journal article (peer-reviewed)abstract
- Three pyridine-substituted fullerene adducts, bis(2,2'-bipyridine)(2'-phenyl-5'-(2-pyridinyl)-2'H-[5.6]fullereno(C60-Ih)[1,9]pyrazole)ruthenium-bis-(hexafluorphosphate) (1), bis(2,2'-bipyridine)(2'-phenyl-5'-(4-(4'-methyl-2,2'-bipyridinyl)-2'H[5,6]fulleroneo(C60-Ih)[1,9]pyrazole)ruthenium-bis(hexafluorophosphate)(2), and bis(2,2'-bipyridine)(1',5'-dihydro-3'-methyl-2'-(4(4'-methyl-2,2'-bipyridinyl))-2'H-[5,6]fullereno(C60-Ih)[1,9]pyrrole)ruthenium-bis(hexafluorophosphate) 83), have been prepared. The common features for these complexes are the short bridges between he fullerene and the pyridine moities.
|
|
| 5. |
- Modin, Judit, 1977-
(author)
-
Synthesis and Evaluation of Photoactive Pyridine Complexes for Electron Transfer Studies and Photoelectrochemical Applications
- 2005
-
Doctoral thesis (other academic/artistic)abstract
- In this thesis, the preparation of new photoactive substances containing mono- and bipyridines coordinated to ruthenium is presented together with initial evaluations of their photoelectrochemical and photophysical properties. Complexes of the type Ru(bpy)2(4-X-py)2 (X = SH, COOH) were prepared and used in Grätzel-type solar cells based on ZnO. The results show that the thiol complex binds to the surface but give rather low solar cell efficiencies. Different routes to obtain Ru(bpy)2(4,4´-dithio-2,2´-bipyridine) were evaluated, among them substitution reactions on 4,4´-dichloro-2,2´-bipyridine coordinated to ruthenium. Due to reactivity issues, the target sulphur-containing complex has not yet been obtained.The synthesis of methanofullerenes, fulleropyrrolidines and –pyrazolines are presented, among them dyads containing Ru(bpy)n-units. A common feature for the dyads is the unusually short linkers between the fullerene and the ruthenium complex. Dyad preparations were in some cases simplified by carrying out the reactions in the presence of silver salts.A preliminary evaluation of the emission of the dyads showed almost complete quenching of the excited state of a pyrrolidine-based dyad, whereas emission remained from the pyrazoline-based ones. Whether this was due to incomplete quenching of the excited states of the ruthenium complex, or induced by the presence of hydrazones has yet to be revealed.The use of fullerene-substituted malonic acid and its ethyl ester as dyes in Grätzel-type solar cells resulted in even lower efficiencies (IPCE) than for bare TiO2. This could be due to electron transfer in the reverse direction compared to what is observed for ruthenium complexes. Thus, these fullerene derivatives are not suitable as sensitisers for Grätzel-type solar cells.
|
|
| 6. |
|
|
| 7. |
- Wallin, Staffan, et al.
(author)
-
Femtosecond Transient Absorption Anisotropy Study on [Ru(bpy)3]2+ and [Ru(bpy)(py)4]2+. Ultrafast Interligand Randomization of the MLCT State
- 2005
-
In: J. Phys. Chem. A. - : American Chemical Society (ACS). ; :109, s. 4697-4704
-
Journal article (peer-reviewed)abstract
- It is known that the relaxed excited state of [Ru(bpy)3]2+ is best described as a metal to ligand charge transfer (MLCT) state having one formally reduced bipyridine and two neutral. Previous reports have suggested [Malone, R. et al. J.Chem. Phys 1991, 95, 8970] that the electron "hops" from ligand to ligand in the MLCT state with a time constant of about 50 ps in acetonitrile. However, we have done transient absorption anisotropy measurements indicating that already after one picosecond the molecule has no memory of which bipyridine was initially photoselected, which suggest an ultrafast interligand randomization of the MLCT state.
|
|
