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41.
We implement time propagation of the nonequilibrium Green function for atoms and molecules by solving the Kadanoff-Baym equations within a conserving self-energy approximation. We here demonstrate the usefulness of time propagation for calculating spectral functions and for describing the correlated electron dynamics in a nonperturbative electric field. We also demonstrate the use of time propagation as a method for calculating charge-neutral excitation energies, equivalent to highly advanced solutions of the Bethe-Salpeter equation. 相似文献
42.
Parmish Kaur Lukas Mai Arbresha Muriqi David Zanders Ramin Ghiyasi Dr. Muhammad Safdar Nils Boysen Manuela Winter Prof. Michael Nolan Prof. Maarit Karppinen Prof. Anjana Devi 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(15):4913-4926
Owing to the limited availability of suitable precursors for vapor phase deposition of rare-earth containing thin-film materials, new or improved precursors are sought after. In this study, we explored new precursors for atomic layer deposition (ALD) of cerium (Ce) and ytterbium (Yb) containing thin films. A series of homoleptic tris-guanidinate and tris-amidinate complexes of cerium (Ce) and ytterbium (Yb) were synthesized and thoroughly characterized. The C-substituents on the N-C-N backbone (Me, NMe2, NEt2, where Me=methyl, Et=ethyl) and the N-substituents from symmetrical iso-propyl (iPr) to asymmetrical tertiary-butyl (tBu) and Et were systematically varied to study the influence of the substituents on the physicochemical properties of the resulting compounds. Single crystal structures of [Ce(dpdmg)3] 1 and [Yb(dpdmg)3] 6 (dpdmg=N,N'-diisopropyl-2-dimethylamido-guanidinate) highlight a monomeric nature in the solid-state with a distorted trigonal prismatic geometry. The thermogravimetric analysis shows that the complexes are volatile and emphasize that increasing asymmetry in the complexes lowers their melting points while reducing their thermal stability. Density functional theory (DFT) was used to study the reactivity of amidinates and guanidinates of Ce and Yb complexes towards oxygen (O2) and water (H2O). Signified by the DFT calculations, the guanidinates show an increased reactivity toward water compared to the amidinate complexes. Furthermore, the Ce complexes are more reactive compared to the Yb complexes, indicating even a reactivity towards oxygen potentially exploitable for ALD purposes. As a representative precursor, the highly reactive [Ce(dpdmg)3] 1 was used for proof-of-principle ALD depositions of CeO2 thin films using water as co-reactant. The self-limited ALD growth process could be confirmed at 160 °C with polycrystalline cubic CeO2 films formed on Si(100) substrates. This study confirms that moving towards nitrogen-coordinated rare-earth complexes bearing the guanidinate and amidinate ligands can indeed be very appealing in terms of new precursors for ALD of rare earth based materials. 相似文献
43.
Infrared Detection of Criegee Intermediates Formed during the Ozonolysis of β‐Pinene and Their Reactivity towards Sulfur Dioxide 下载免费PDF全文
Jennifer Ahrens Philip T. M. Carlsson Nils Hertl Prof. Dr. Matthias Olzmann Mark Pfeifle Dr. J. Lennard Wolf Dr. Thomas Zeuch 《Angewandte Chemie (International ed. in English)》2014,53(3):715-719
Recently, direct kinetic experiments have shown that the oxidation of sulfur dioxide to sulfur trioxide by reaction with stabilized Criegee intermediates (CIs) is an important source of sulfuric acid in the atmosphere. So far, only small CIs, generated in photolysis experiments, have been directly detected. Herein, it is shown that large, stabilized CIs can be detected in the gas phase by FTIR spectroscopy during the ozonolysis of β‐pinene. Their transient absorption bands between 930 and 830 cm?1 appear only in the initial phase of the ozonolysis reaction when the scavenging of stabilized CIs by the reaction products is slow. The large CIs react with sulfur dioxide to give sulfur trioxide and nopinone with a yield exceeding 80 %. Reactant consumption and product formation in time‐resolved β‐pinene ozonolysis experiments in the presence of sulfur dioxide have been kinetically modeled. The results suggest a fast reaction of sulfur dioxide with CIs arising from β‐pinene ozonolysis. 相似文献
44.
A Deadly Organometallic Luminescent Probe: Anticancer Activity of a ReI Bisquinoline Complex 下载免费PDF全文
Dr. Igor Kitanovic Suzan Can Dr. Hamed Alborzinia Dr. Ana Kitanovic Vanessa Pierroz Anna Leonidova Dr. Antonio Pinto Priv. Doz. Dr. Bernhard Spingler Priv. Doz. Dr. Stefano Ferrari Roberto Molteni Dr. Andreas Steffen Prof. Dr. Nils Metzler‐Nolte Prof. Dr. Stefan Wölfl Prof. Dr. Gilles Gasser 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(9):2496-2507
The photophysical properties of [Re(CO)3(L ‐N3)]Br (L ‐N3=2‐azido‐N,N‐bis[(quinolin‐2‐yl)methyl]ethanamine), which could not be localized in cancer cells by fluorescence microscopy, have been revisited in order to evaluate its use as a luminescent probe in a biological environment. The ReI complex displays concentration‐dependent residual fluorescence besides the expected phosphorescence, and the nature of the emitting excited states have been evaluated by DFT and time‐dependent (TD) DFT methods. The results show that fluorescence occurs from a 1LC/MLCT state, whereas phosphorescence mainly stems from a 3LC state, in contrast to previous assignments. We found that our luminescent probe, [Re(CO)3(L ‐N3)]Br, exhibits an interesting cytotoxic activity in the low micromolar range in various cancer cell lines. Several biochemical assays were performed to unveil the cytotoxic mechanism of the organometallic ReI bisquinoline complex. [Re(CO)3(L ‐N3)]Br was found to be stable in human plasma indicating that [Re(CO)3(L ‐N3)]Br itself and not a decomposition product is responsible for the observed cytotoxicity. Addition of [Re(CO)3(L ‐N3)]Br to MCF‐7 breast cancer cells grown on a biosensor chip micro‐bioreactor immediately led to reduced cellular respiration and increased glycolysis, indicating a large shift in cellular metabolism and inhibition of mitochondrial activity. Further analysis of respiration of isolated mitochondria clearly showed that mitochondrial respiratory activity was a direct target of [Re(CO)3(L ‐N3)]Br and involved two modes of action, namely increased respiration at lower concentrations, potentially through increased proton transport through the inner mitochondrial membrane, and efficient blocking of respiration at higher concentrations. Thus, we believe that the direct targeting of mitochondria in cells by [Re(CO)3(L ‐N3)]Br is responsible for the anticancer activity. 相似文献
45.
Aryl–Phenyl Scrambling in Intermediate Organopalladium Complexes: A Gas‐Phase Study of the Mizoroki–Heck Reaction 下载免费PDF全文
Lukas Fiebig Dr. Nils Schlörer Prof. Hans‐Günther Schmalz Priv.‐Doz. Dr. Mathias Schäfer 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(17):4906-4910
The intramolecular aryl–phenyl scrambling reaction within palladium–DPPP–aryl complex (DPPP=1,3‐bis(diphenylphosphino)propane) ions was analyzed by state‐of‐the‐art tandem MS, including gas‐phase ion/molecule reactions. The Mizoroki–Heck cross‐coupling reaction was performed in the gas phase, and the intrinsic reactivity of important intermediates could be examined. Moreover, linear free‐energy correlations were applied, and a mechanism for the scrambling reaction proceeding via phosphonium cations was assumed. 相似文献
46.
Dr. Andreas Lerchen Dr. Narasimhulu Gandhamsetty Elliot H. E. Farrar Dr. Nils Winter Dr. Johannes Platzek Dr. Matthew N. Grayson Prof. Dr. Varinder K. Aggarwal 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(51):23307-23311
(−)-Finerenone is a nonsteroidal mineralocorticoid receptor antagonist currently in phase III clinical trials for the treatment of chronic kidney disease in type 2 diabetes. It contains an unusual dihydronaphthyridine core. We report a 6-step synthesis of (−)-finerenone, which features an enantioselective partial transfer hydrogenation of a naphthyridine using a chiral phosphoric acid catalyst with a Hantzsch ester. The process is complicated by the fact that the naphthyridine exists as a mixture of two atropisomers that react at different rates and with different selectivities. The intrinsic kinetic resolution was converted into a kinetic dynamic resolution at elevated temperature, which enabled us to obtain (−)-finerenone in both high yield and high enantioselectivity. DFT calculations have revealed the origin of selectivity. 相似文献
47.
Dilcan Dirican Nils Pfister Martin Wozniak Prof. Dr. Thomas Braun 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(31):6945-6963
Binary sulfur fluorides exhibit an interesting reactivity towards transition metal complexes. They open up routes for the generation of sulfur-containing building blocks. Often ligands with particular properties can be constructed. This includes their ability to transfer sulfur atoms or polysulfide units as well as fluorination reactions. This Minireview provides an insight into the reactivity of the binary and ternary sulfur halides S2Cl2, SCl2, SF4, SF6 and SF5Cl towards transition-metal compounds. 相似文献
48.
Simon Ludwanowski Dr. Meral Ari Karsten Parison Somar Kalthoum Paula Straub Nils Pompe Prof. Dr. Stefan Weber Priv.-Doz. Dr. Michael Walter Prof. Dr. Andreas Walther 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(58):13203-13212
Arylazopyrazoles are an emerging class of photoswitches with redshifted switching wavelength, high photostationary states, long thermal half-lives and facile synthetic access. Understanding pathways for a simple modulation of the thermal half-lives, while keeping other parameters of interest constant, is an important aspect for out-of-equilibrium systems design and applications. Here, it is demonstrated that the thermal half-life of a water-soluble PEG-tethered arylazo-bis(o-methylated)pyrazole (AAP) can be tuned by more than five orders of magnitude using simple pH adjustment, which is beyond the tunability of azobenzenes. The mechanism of thermal relaxation is investigated by thorough spectroscopic analyses and density functional theory (DFT) calculations. Finally, the concepts of a tunable half-life are transferred from the molecular scale to the material scale. Based on the photochromic characteristics of E- and Z-AAP, transient information storage is showcased in form of light-written patterns inside films cast from different pH, which in turn leads to different times of storage. With respect to prospective precisely tunable materials and time-programmed out-of-equilibrium systems, an externally tunable half-life is likely advantageous over changing the entire system by the replacement of the photoswitch. 相似文献
49.
Nils Svanstedt Niklas Wellander John Wyller 《Numerical Methods for Partial Differential Equations》1996,12(4):423-440
A numerical algorithm is constructed for the solution to a class of nonlinear parabolic operators in the case of homogenization. We consider parabolic operators of the form d/dt + Aϵ, where Aϵ is monotone. More precisely, we consider the case when Aϵu=−div (a(x/ϵ, e/ϵk) |Du|p−2Du), where p≥2 and k>0. © 1996 John Wiley & Sons, Inc. 相似文献
50.
Nils Metzler 《Nachrichten aus der Chemie》1994,42(12):1254-1256
„First International Conference on the Chemistry of the Alkali and Alkaline Earth Metals”︁ - die unter diesem Titel Ende September in Cambridge (UK) abgehaltene Tagung zeigte, daß sich die Chemie der Elemente der ersten beiden Hauptgruppen von einem esoterischen Spiel mit hochempfindlichen Verbindungen zu einem aktuellen und vielseitigen Zweig der Chemie entwickelt hat. 相似文献