| 1. |
- Duan, Lele, et al.
(author)
-
A molecular ruthenium catalyst with water-oxidation activity comparable to that of photosystem II
- 2012
-
In: Nature Chemistry. - 1755-4330 .- 1755-4349. ; 4:5, s. 418-423
-
Journal article (peer-reviewed)abstract
- Across chemical disciplines, an interest in developing artificial water splitting to O-2 and H-2, driven by sunlight, has been motivated by the need for practical and environmentally friendly power generation without the consumption of fossil fuels. The central issue in light-driven water splitting is the efficiency of the water oxidation, which in the best-known catalysts falls short of the desired level by approximately two orders of magnitude. Here, we show that it is possible to close that 'two orders of magnitude' gap with a rationally designed molecular catalyst [Ru(bda)(isoq)(2)] (H(2)bda = 2,2'-bipyridine-6,6'-dicarboxylic acid; isoq = isoquinoline). This speeds up the water oxidation to an unprecedentedly high reaction rate with a turnover frequency of >300 s(-1). This value is, for the first time, moderately comparable with the reaction rate of 100-400 s(-1) of the oxygen-evolving complex of photosystem II in vivo.
|
|
| 2. |
|
|
| 3. |
|
|
| 4. |
- Fromager, E., et al.
(author)
-
Spin-orbit effects in electron transfer in neptunyl(VI)-neptunyl(V) complexes in solution
- 2005
-
In: Journal of Physical Chemistry A. - : American Chemical Society (ACS). - 1089-5639 .- 1520-5215. ; 109:22, s. 4957-4960
-
Journal article (peer-reviewed)abstract
- The spin-orbit effects were investigated on the complexes involved in the electron self-exchange between Np(V) and Np(VI) in both the outer-sphere and inner-sphere mechanisms, the latter for binuclear complexes containing hydroxide, fluoride, and carbonate as bridging ligands. Results obtained with the variation-perturbation and the multireference single excitation spin-orbit Cl calculations are compared. Both effects due to different relaxations of spinors within a multiplet (spin-orbit relaxation) and scalar (electrostatic) relaxation effects in the excited states are accounted for in the latter scheme. The results show that the scalar (electrostatic) relaxation is well described by the single-excitation spin-orbit CI, and that spin-orbit relaxation effects are small in the Np complexes, as in the lighter d-transition elements but in contrast to the main group elements.
|
|
| 5. |
|
|
| 6. |
- Frölander, Anders, et al.
(author)
-
Conformational preferences and enantiodiscrimination of phosphino-4-(1-hydroxyalkyl)oxazoline-metal-olefin complexes resulting from an OH-metal hydrogen bond
- 2005
-
In: Journal of Organic Chemistry. - : American Chemical Society (ACS). - 0022-3263 .- 1520-6904. ; 70:24, s. 9882-9891
-
Journal article (peer-reviewed)abstract
- Phosphinooxazolines carrying (1-hydroxy-1-phenyl)methyl and (1-methoxy-1-phenyl)methyl substituents in the 4 position of the oxazoline ring exhibit contrasting behavior in Pd-and Ir-catalyzed allylic alkylations. Whereas catalysts with the methoxy-containing ligand generally provide products with high ee's, use of catalysts prepared from the hydroxy-containing ligand results in products with low ee's or even racemates. DFT calculations suggest the presence of a hydrogen bond with Pd(0) as the proton acceptor in the hydroxy-containing olefin-Pd(0) complexes, which induces a conformational change in the ligand, leading to different stereoselectivity.
|
|
| 7. |
- Frölander, Anders, et al.
(author)
-
OH-Metal hydrogen bond in Pd- and Ir-catalyzed allylic alkylations
- 2006
-
In: ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY. ; , s. ORGN-259-
-
Conference paper (other academic/artistic)abstract
- Phosphinooxazolines carrying 4-hydroxybenzyl and 4-methoxybenzyl substituents exhibit contrasting behavior in Pd- and Ir-catalyzed allylic alkylations. Whereas catalysts with the methoxy-contg. ligand generally provide products with high ee's, use of catalysts prepd. from the hydroxy contg. ligand results in products with low ee's or even racemates. DFT calcns. suggest the presence of a hydrogen bond with Pd(0) as proton acceptor in the hydroxy contg. olefin Pd(0) complexes, which induces a conformational change in the ligand leading to different stereoselectivity. We have previously obsd. the same kind of dramatic changes of enantioselectivities in palladium-catalyzed allylations upon methylation of hydroxy-contg. pyridinooxazolines and bisoxazolines.
|
|
| 8. |
- Gelmukhanov, F, et al.
(author)
-
Collapse of vibrational structure in spectra of resonant x-ray Raman scattering
- 1997
-
In: Physical Review A. Atomic, Molecular, and Optical Physics. - 1050-2947 .- 1094-1622. ; 56:1, s. 256-264
-
Journal article (peer-reviewed)abstract
- Extreme narrowing, or collapse, of electron-vibrational bands is predicted as a new phenomenon in resonant radiative and nonradiative x-ray scattering (RXS) spectra. It is shown that in the inelastic scattering case, that is, when the potential surfaces of ground and final slates are different, a considerable narrowing of the vibronic RXS band results from detuning the excitation Photon frequency omega away from the absorption resonance. By fine tuning the frequency, this may under special circumstances also occur in the region of strong photoabsorption. In the case of elastic Rayleigh scattering, that is, when the potential surfaces of ground and final states are identical, the narrowing results in a total collapse to a single resonance by detuning the frequency. The theory predicts how the differencies in vibrational structure of resonant and nonresonant photoemission spectra depends on the excitation frequency. The effect of frequency detuning on complex spectral multilevel structures due to multiplet: and spin-orbit splittings is discussed qualitatively. It is shown that the notion of: duration time for the x-ray scattering process plays a crucial role in the understanding of RXS spectra.
|
|
| 9. |
- Gel’mukhanov, Faris, et al.
(author)
-
Duration of x-ray Raman scattering
- 1999
-
In: Physical Review A. Atomic, Molecular, and Optical Physics. - 1050-2947 .- 1094-1622. ; 59:1, s. 380-389
-
Journal article (peer-reviewed)abstract
- There has recently been much interest in using the notion of a duration time to analyze resonant x-ray Raman scattering (RXS) of atoms, molecules, and solids. This notion implies a selection of processes with different time scales responsible for the formation x-ray Raman spectra, and has been useful for actual predictions of various phenomena associated with RXS and that subsequently have been experimentally verified. However, the notion of a duration time for the x-ray scattering event can also have some paradoxical consequences, as when comparing the RXS duration with the relaxation time of the wave packet evolution in the case when the inverse detuning of the excitation energy is shorter than the time of flight or the lifetime of the core excited state. We present here a solution of this contradiction and give a detailed analysis of the notion of the duration time for RXS. It is shown that this time is complex and consists of two qualitatively different contributions. The first originates in the irreversible decay of the core excited state, while the imaginary part is caused by a reversible dephasing in the time domain. We investigate also the evolution of the wave packets of bound and dissociative states to stationary distributions. The theoretical analysis is accompanied by numerical examples of the time evolution of the wave packet in bound and dissociative core excited states of the N2 and HCl molecules.
|
|
| 10. |
- Gelmukhanov, F, et al.
(author)
-
Restoration of selection rules in nonadiabatic resonant inelastic x-ray scattering
- 1997
-
In: Journal of Experimental and Theoretical Physics. - : Pleiades Publishing Ltd. - 1063-7761 .- 1090-6509. ; 85:1, s. 20-26
-
Journal article (peer-reviewed)abstract
- Recently a new effect in the Raman scattering of x-ray radiation has been predicted theoretically and discovered in experiments, the effect of restoration of the selection rules for the scattering tensor under strong electron-vibrational interaction. We propose a fairly simple model for describing this effect, a model that allows for an exact solution and takes into account the real vibrational structure of the molecule and electron-vibrational interaction.
|
|
