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81.
Theodosis Giousis Georgia Potsi Antonios Kouloumpis Konstantinos Spyrou Yiannis Georgantas Nikolaos Chalmpes Konstantinos Dimos Myrsini‐Kiriaki Antoniou Georgios Papavassiliou Athanasios B. Bourlinos Hae Jin Kim Vijay Kumar Shankarayya Wadi Saeed Alhassan Majid Ahmadi Bart J. Kooi Graeme Blake Daniel M. Balazs Maria A. Loi Dimitrios Gournis Petra Rudolf 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2021,133(1):364-369
Germanane (GeH), a germanium analogue of graphane, has recently attracted considerable interest because its remarkable combination of properties makes it an extremely suitable candidate to be used as 2D material for field effect devices, photovoltaics, and photocatalysis. Up to now, the synthesis of GeH has been conducted by substituting Ca by H in a β‐CaGe2 layered Zintl phase through topochemical deintercalation in aqueous HCl. This reaction is generally slow and takes place over 6 to 14 days. The new and facile protocol presented here allows to synthesize GeH at room temperature in a significantly shorter time (a few minutes), which renders this method highly attractive for technological applications. The GeH produced with this method is highly pure and has a band gap (Eg) close to 1.4 eV, a lower value than that reported for germanane synthesized using HCl, which is promising for incorporation of GeH in solar cells. 相似文献
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Asymmetric,Three‐Component,One‐Pot Synthesis of Spiropyrazolones and 2,5‐Chromenediones from Aldol Condensation/NHC‐Catalyzed Annulation Reactions
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Dr. Lei Wang Sun Li Dr. Pankaj Chauhan Dr. Daniel Hack Arne R. Philipps Dr. Rakesh Puttreddy Prof. Dr. Kari Rissanen Prof. Dr. Gerhard Raabe Prof. Dr. Dieter Enders 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(15):5123-5127
A novel one‐pot, three‐component diastereo‐ and enantioselective synthesis of spiropyrazolones has been developed involving the aldol condensation of an enal to generate α,β‐unsaturated pyrazolones, which react with a second equivalent of enal through an N‐heterocyclic carbene (NHC)‐catalyzed [3+2] annulation. The desired spirocyclopentane pyrazolones are obtained in moderate to good yields and good to excellent stereoselectivities. Alternatively, starting from cyclic 1,3‐diketones, 2,5‐chromenediones are available through [2+4] annulation. 相似文献
85.
[reaction: see text] A new method for the synthesis of 2',3'-dideoxynucleoside analogues has been developed. An electrochemical activation of 2-substituted furans is followed by the coupling with a pyrimidine or purine base. This gives planar furyl nucleosides as key intermediates, which are hydrogenated cis-selectively to give the corresponding beta-2',3'-dideoxynucleosides as racemic mixtures. An enzymatic kinetic resolution gives rise to beta-D- and beta-L-configured derivatives in high optical purity. This is exemplified by the synthesis of beta-D- and beta-L-3'-deoxythymidine. 相似文献
86.
C. M. Dion P. Sjölund S. J.H. Petra S. Jonsell M. Nylén L. Sanchez-Palencia A. Kastberg 《The European physical journal. Special topics》2008,159(1):11-17
We study a Brownian motor, based on cold atoms in optical lattices, where atomic motion can be induced in a controlled manner
in an arbitrary direction, by rectification of isotropic random fluctuations. In contrast with ratchet mechanisms, our Brownian
motor operates in a potential that is spatially and temporally symmetric, in apparent contradiction to the Curie principle.
Simulations, based on the Fokker-Planck equation, allow us to gain knowledge on the qualitative behaviour of our Brownian
motor. Studies of Brownian motors, and in particular ones with unique control properties, are of fundamental interest because
of the role they play in protein motors and their potential applications in nanotechnology. In particular, our system opens
the way to the study of quantum Brownian motors. 相似文献
87.
Alfonso J. Chirinos-Padrn Petra H. Hernndez Felipe A. Surez 《Polymer Degradation and Stability》1988,20(3-4):237-255
The effect of Cr(III), Fe(III) and Cu(II) ions, at trace levels, on the effectiveness of four commercial antioxidant systems, viz. Topanol, Santowhite, Hostanox 03 and Irganox 1425, in polypropylene (PP) films is examined using infra-red and second-order derivative uv spectroscopy. The results show that at these levels the metal ions have a minor effect on the unstabilised polymer. However, the ions can have a beneficial or adverse effect on antioxidant activity, particularly under oven ageing conditions. The observed effect depends on the metal/antioxidant system, and is attributed to an indirect interaction between the components which can delay or accelerate antioxidant decomposition in the polymer. An exception to this behaviour is the metal complex Irganox 1425, which interacts strongly with copper ions in the polymer matrix. The antioxidant is partially transformed by copper ions during the compression moulding stage. The beneficial effect present in some cases is in direct contrast with what has generally been observed in studies using unstabilised polymers. 相似文献
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The gas phase infrared spectra of monoisotopic H3Si35Cl and H3Si37Cl have been studied in the region near 2200 cm?1 with a resolution of 0.012 and 0.04 cm?1, respectively, and rotational fine structure for ΔJ = ±1 branches has been resolved. In addition, some information on ν3 + ν4 of H3Si35Cl near 2750 cm?1 has been obtained. ν1 and ν4 are weakly coupled by Coriolis x, y resonance, , only the upper states K′ = 2, l = 0 and K′ = 1, l = ?1 being substantially affected. Local perturbation due to rotational l(±1, ±1)-type resonance with ν3 + ν5+1 + ν6+1 and ν3 + ν5+1 + ν6?1 is revealed in the ΔK = +1 and ?1 branches, respectively. From a fit of the experimental line positions, standard deviations of 1.4 and 3.8 × 10?3 cm?1, respectively, to a model with five interacting levels conventional excited state parameters and interaction constants have been obtained. In the fundamentals are ν1, and ν4, , respectively. Q branches of the “hot” band (ν3 + ν4) ? ν3 and of ν4 of the 29Si and 30Si species have been detected. 相似文献