| 1. |
- Czapla-Masztafiak, Joanna, et al.
(författare)
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Mechanism of hydrolysis of a platinum(IV) complex discovered by atomic telemetry
- 2018
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Ingår i: Journal of Inorganic Biochemistry. - : ELSEVIER SCIENCE INC. - 0162-0134 .- 1873-3344. ; 187, s. 56-61
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Tidskriftsartikel (refereegranskat)abstract
- Herein we report on the hydrolysis mechanism of [Pt{N(p-HC6F4)CH2}(2)(NC5H5)(2)(OH)(2)], a platinum(IV) complex that exhibits anti-cancer properties. Atomic telemetry, an in situ technique based on electron structure sensitive X-ray spectroscopy, revealed that hydrolysis preceded any reduction of the metal center. The obtained results are complemented with F-19 NMR measurements and theoretical calculations and support the observation that this Pt-II complex does not reduce spontaneously to Ptll in HEPES buffer solution at pH 7.4 and after 24 h incubation. These results are of importance for the design of novel Pt-based coordination complexes as well as understanding their behavior under physiological conditions.
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| 2. |
- Goszewska, Ilona, et al.
(författare)
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Boosting the Performance of Nano-Ni Catalysts by Palladium Doping in Flow Hydrogenation of Sulcatone
- 2020
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Ingår i: Catalysts. - : MDPI. - 2073-4344. ; 10:11
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Tidskriftsartikel (refereegranskat)abstract
- The effect of Pd doping on nano-Ni catalyst hydrogenation aptitude in sulcatone (6-methyl-5-hepten-2-one) hydrogenation was investigated. Obtained results demonstrated that the addition of non-catalytic amounts of Pd to the surface of parent Ni catalyst improves the activity to the extent that it surpassed the activity of 2.16 wt% Pd catalyst (model catalyst) at optimal reaction conditions in the flow hydrogenation of an unsaturated ketone. Pd doping improves hydrogen activation on the catalyst, which was found to be a rate-limiting step using kinetic isotopic measurements and theoretical calculations.
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| 3. |
- Kochman, Michal Andrzej, et al.
(författare)
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Simulation and analysis of the relaxation dynamics of a photochromic furylfulgide
- 2022
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Ingår i: Physical Chemistry, Chemical Physics - PCCP. - : Royal Society of Chemistry. - 1463-9076 .- 1463-9084. ; 24:30, s. 18103-18118
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Tidskriftsartikel (refereegranskat)abstract
- Furylfulgides, a class of photochromic organic compounds, show a complex system of photoinduced reactions. In the present study, the excited-state dynamics of the E-alpha and E-beta isomers of a representative furylfulgide is modelled with the use of nonadiabatic molecular dynamics simulations. Moreover, a pattern recognition algorithm is employed in order to automatically identify relaxation pathways, and to quantify the photoproduct distributions. The simulation results indicate that, despite differing only in the orientation of the furyl group, the two isomers show markedly different photochemical behaviour. The predominant E-alpha isomer undergoes photocyclisation with a quantum yield (QY) of 0.27 +/- 0.10. For this isomer, the undesired E -> Z photoisomerisation around the central double bond represents a minor side reaction, with a QY of 0.09 +/- 0.07. In contrast, the minority E-beta isomer, which is incapable of photocyclisation, undergoes efficient E -> Z photoisomerisation, with a QY as high as 0.56 +/- 0.14. The relaxation kinetics and the photoproduct distributions are interpreted in the light of the available experimental data.
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| 4. |
- Kochman, Michał Andrzej, et al.
(författare)
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Simulation and Analysis of the Transient Absorption Spectrum of 4-(N,N-Dimethylamino)benzonitrile (DMABN) in Acetonitrile
- 2021
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Ingår i: Journal of Physical Chemistry A. - : American Chemical Society (ACS). - 1089-5639 .- 1520-5215. ; 125:39, s. 8635-8648
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Tidskriftsartikel (refereegranskat)abstract
- 4-(N,N-Dimethylamino)benzonitrile (DMABN) is a well-known model compound for dual fluorescence ﹣in sufficiently polar solvents, it exhibits two distinct fluorescence emission bands. The interpretation of its transient absorption (TA) spectrum in the visible range is the subject of a long-standing controversy. In the present study, we resolve this issue by calculating the TA spectrum on the basis of nonadiabatic molecular dynamics simulations. An unambiguous assignment of spectral signals to specific excited-state structures is achieved by breaking down the calculated spectrum into contributions from twisted and nontwisted molecular geometries. In particular, the much-discussed excited-state absorption band near 1.7 eV (ca. 700nm) is attributed to the near-planar locally excited (LE) minimum on the S1 state. On the technical side, our study demonstrates that the second-order approximate coupled cluster singles and doubles (CC2) method can be used successfully to calculate the TA spectra of moderately large organic molecules, provided that the system in question does not approach a crossing between the lowest excited state and the singlet ground state within the time frame of the simulation.
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| 5. |
- Szlachetko, Jakub, et al.
(författare)
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Hidden gapless states during thermal transformations of preorganized zinc alkoxides to zinc oxide nanocrystals
- 2018
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Ingår i: Materials Horizons. - : Royal Society of Chemistry (RSC). - 2051-6347 .- 2051-6355. ; 5:5, s. 905-911
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Tidskriftsartikel (refereegranskat)abstract
- Zinc oxide (ZnO) is one of the most versatile semiconductor materials with multifarious potential applications. Easily accessible alkylzinc alkoxides have been widely exploited as single-source precursors of ZnO-based nanomaterials but their multi-step decomposition pathways have not been understood in detail. Herein, the formation mechanism of ZnO nanocrystals via solid-state thermal decomposition of a model pre-organised alkylzinc alkoxide precursor, i.e. [tBuZn(mu(3)-OtBu)](4), is elucidated using in situ valence-to-core X-ray emission (v2c-XES) and high energy resolution off-resonant spectroscopy (HEROS) in conjunction with theoretical calculations. Combination of in situ spectroscopic measurements and theoretical simulations indicates that the precursor structural evolution is initiated by the homolytic cleavage of the R-Zn bond, which leads to the formation of a transient radical ([center dot Zn(mu(3)-OR)][RZn(mu(3)-OR)](3)) species, which is responsible for the initial decomposition process. The ensuing multistep transformations involve the formation of intermediate radical zinc oxo-alkoxide clusters with gapless electronic states. Hitherto, the formation of clusters of this type has not been considered either as intermediate structures en route to a semiconductor ZnO phase or as potential species accounting for various defect states of ZnO NCs, particularly the singly charged oxygen vacancy, V-o(+).
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| 6. |
- Zienkiewicz-Machnik, Malgorzata, et al.
(författare)
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Tuning Nano-Nickel Catalyst Hydrogenation Aptitude by On-the-Fly Zirconium Doping
- 2020
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Ingår i: ChemCatChem. - : Wiley. - 1867-3880 .- 1867-3899. ; 12:11, s. 3132-3138
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Tidskriftsartikel (refereegranskat)abstract
- The effect of nano‐Ni catalyst post‐synthetic Zr‐modification on hydrogenation reaction of 6‐methyl‐5‐hepten‐2‐one was investigated in a fixed bed continuous‐flow micro‐reactor to produce fine chemicals. The catalytic performance revealed that Zr‐doping achieved by surface organometallic chemistry approach modifies the natural aptitude of nickel to hydrogenate C=C bond, since the addition of small quantities of zirconium significantly increased the amount of unsaturated and saturated alcohols formed in 6‐methyl‐5‐hepten‐2‐one hydrogenation. Quantum chemical calculations revealed a stronger interaction between Zr←O=C that promotes the formation of C=C semihydrogenation product and enhances the probability of complete hydrogenation. The on‐the‐fly strategy presented herein enables for rapid optimization and understanding of catalytic processes.
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| 7. |
- Zienkiewicz-Machnik, Malgorzata, et al.
(författare)
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Tuning nano-nickel selectivity with tin in flow hydrogenation of 6-methyl-5-hepten-2-one by surface organometallic chemistry modification
- 2018
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Ingår i: Catalysis Today. - : ELSEVIER SCIENCE BV. - 0920-5861 .- 1873-4308. ; 308, s. 38-44
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Tidskriftsartikel (refereegranskat)abstract
- Chemoselective flow hydrogenation of 6-methyl-5-hepten-2-one was performed over nano-nickel catalysts. The parent catalyst composed solely of nickel nanoparticles grafted on the polymeric resin exhibited high activity and selectivity towards C=C bond saturation but its modification with small quantities of tin significantly increased its ability to perform C=O bond hydrogenation. The post-synthetic modification of the parent catalyst was achieved by surface organometallic chemistry approach and performed in the same flow micro-reactor, which was used for the catalytic studies, providing a methodology for online modification of parent catalysts.
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