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991.
Xu J Ding Y Peucheret C Seoane J Mulvad HC Galili M Xue W Mørk J Jeppesen P 《Optics letters》2011,36(9):1560-1562
We propose and demonstrate the use of a single semiconductor optical amplifier (SOA) and optical filtering to time demultiplex tributaries from an optical time division multiplexing-differential phase shift keying (OTDM-DPSK) signal. The scheme takes advantage of the fact that phase variations added to the target channel by cross-phase modulation from the control signal are effectively subtracted in the differential demodulation scheme employed for DPSK signals. Demultiplexing from 80 to 40 Gbit/s is demonstrated with moderate power penalty using an SOA with recovery time twice as long as the bit period at 80 Gbit/s. Large dynamic ranges for the input power and SOA current are experimentally demonstrated. The scheme is expected to be scalable toward higher bit rates. 相似文献
992.
Boess E Sureshkumar D Sud A Wirtz C Farès C Klussmann M 《Journal of the American Chemical Society》2011,133(21):8106-8109
The mechanism of an aerobic copper-catalyzed oxidative coupling reaction with N-phenyl tetrahydroisoquinoline was investigated. The oxidized species formed from the reaction of the amine with the copper catalyst were analyzed by NMR-spectroscopy. An iminium dichlorocuprate was found to be the reactive intermediate and could be structurally characterized by X-ray crystallography. The effect of methanol to effectively stabilize the iminium ion was investigated and shown to be beneficial in an oxidative allylation reaction. 相似文献
993.
Selloum Djamel Techer Vincent Henni Abdellah Tingry Sophie Cretin Marc Innocent Christophe 《Journal of Solid State Electrochemistry》2020,24(3):623-631
Journal of Solid State Electrochemistry - Biofuel cells are an attractive alternative to conventional fuel cells, because they use biological catalysts. We report in this article the construction... 相似文献
994.
Robert N. Grass Reinhard Heckel Christophe Dessimoz Wendelin J. Stark 《Angewandte Chemie (International ed. in English)》2020,59(22):8476-8480
Today, we can read human genomes and store digital data robustly in synthetic DNA. Herein, we report a strategy to intertwine these two technologies to enable the secure storage of valuable information in synthetic DNA, protected with personalized keys. We show that genetic short tandem repeats (STRs) contain sufficient entropy to generate strong encryption keys, and that only one technology, DNA sequencing, is required to simultaneously read the key and the data. Using this approach, we experimentally generated 80 bit strong keys from human DNA, and used such a key to encrypt 17 kB of digital information stored in synthetic DNA. Finally, the decrypted information was recovered perfectly from a single massively parallel sequencing run. 相似文献
995.
996.
Dr. Bo Peng Dr. Danny Geerdink Dr. Christophe Farès Prof. Dr. Nuno Maulide 《Angewandte Chemie (International ed. in English)》2014,53(21):5462-5466
A new approach for the fully chemoselective α‐arylation of amides is presented. By means of electrophilic amide activation, aryl groups can be regioselectively introduced α‐ to amides, even in the presence of esters and alkyl ketones. Mechanistic studies reveal key reaction intermediates and emphasize a remarkably subtle base effect in this transformation. 相似文献
997.
Patrick Wolf Maxence Valla Dr. Aaron J. Rossini Dr. Aleix Comas‐Vives Dr. Francisco Núñez‐Zarur Prof. Dr. Bernard Malaman Dr. Anne Lesage Prof. Dr. Lyndon Emsley Prof. Dr. Christophe Copéret Prof. Dr. Ive Hermans 《Angewandte Chemie (International ed. in English)》2014,53(38):10179-10183
Dynamic nuclear polarization surface enhanced NMR (DNP‐SENS), Mössbauer spectroscopy, and computational chemistry were combined to obtain structural information on the active‐site speciation in Sn‐β zeolite. This approach unambiguously shows the presence of framework SnIV‐active sites in an octahedral environment, which probably correspond to so‐called open and closed sites, respectively (namely, tin bound to three or four siloxy groups of the zeolite framework). 相似文献
998.
Understanding a Host–Guest Model System through 129Xe NMR Spectroscopic Experiments and Theoretical Studies
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Emmanuelle Dubost Jean‐Pierre Dognon Bernard Rousseau Gaëlle Milanole Christophe Dugave Yves Boulard Estelle Léonce Céline Boutin Patrick Berthault 《Angewandte Chemie (International ed. in English)》2014,53(37):9837-9840
Gaining an understanding of the nature of host–guest interactions in supramolecular complexes involving heavy atoms is a difficult task. Described herein is a robust simulation method applied to complexes between xenon and members of a cryptophane family. The calculated chemical shift of xenon caged in a H2O2 probe, as modeled by quantum chemistry with complementary‐orbital, topological, and energy‐decomposition analyses, is in excellent agreement with that observed in hyperpolarized 129Xe NMR spectra. This approach can be extended to other van der Waals complexes involving heavy atoms. 相似文献
999.
Tuning the Guest‐Binding Ability of a Helically Folded Capsule by In Situ Modification of the Aromatic Oligoamide Backbone
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Dr. Guillaume Lautrette Dr. Christophe Aube Dr. Yann Ferrand Dr. Muriel Pipelier Dr. Virginie Blot Dr. Christine Thobie Dr. Brice Kauffmann Prof. Didier Dubreuil Dr. Ivan Huc 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(6):1547-1553
Starting from a previously described aromatic oligoamide helically folded capsule that binds tartaric acid with high affinity and diastereoselectivity, we demonstrate the feasibility of the direct in situ modification of the helix backbone, which results in a conformational change that reduces its affinity for guests by two orders of magnitude. Specifically, ring contraction of the central pyridazine unit into a pyrrole in the full helical sequence was investigated by using electrochemical and chemical processes. The sequence containing the pyrrole was synthesized independently in a convergent manner to ascertain its structure. The conformation of the pyrrolic folded capsule was elucidated in the solid state by X‐ray crystallography and in solution by using 1H and 13C NMR spectroscopy. Solution studies revealed an unanticipated solvent‐dependent equilibrium between the anti–anti and syn–syn conformations of the pyrrole ring with respect to its two adjacent pyridine units. Titrations of the pyrrole‐containing sequence monitored by 1H NMR spectroscopy confirmed the expected drop in affinity for tartaric acid and malic acid that arises from the conformation change in the backbone that follows the replacement of the pyridazine by a pyrrole. The reduction of the pyridazine to a pyrrole was characterized by cyclic voltammetry both on the entire sequence and on a shorter precursor. The lower cathodic potential of the precursor made its preparative‐scale electroreduction possible. Direct in situ modification of the pyridazine within the entire capsule sequence was achieved chemically by using zinc in acetic acid. 相似文献
1000.
Dr. Elisabet Öberg Dr. Andreas Orthaber Dr. Christophe Lescop Prof. Régis Réau Prof. Muriel Hissler Prof. Sascha Ott 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(27):8421-8432
Phosphole‐substituted phosphaalkenes (PPAs) of the general formula Mes*P?C(CH3)?(C4H2P(Ph))?R 5 a – c (Mes*=2,4,6‐tBu3Ph; R=2‐pyridyl ( a ), 2‐thienyl ( b ), phenyl ( c )) have been prepared from octa‐1,7‐diyne‐substituted phosphaalkenes by utilizing the Fagan–Nugent route. The presence of two differently hybridized phosphorus centers (σ2,λ3 and σ3,λ3) in 5 offers the possibility to selectively tune the HOMO–LUMO gap of the compounds by utilizing the different reactivity of the two phosphorus heteroatoms. Oxidation of 5 a – c by sulfur proceeds exclusively at the σ3,λ3‐phosphorus atom, thus giving rise to the corresponding thioxophospholes 6 a – c . Similarly, 5 a is selectively coordinated by AuCl at the σ3,λ3‐phosphorus atom. Subsequent second AuCl coordination at the σ2,λ3‐phosphorus heteroatom results in a dimetallic species that is characterized by a gold–gold interaction that provokes a change in π conjugation. Spectroscopic, electrochemical, and theoretical investigations show that the phosphaalkene and the phosphole both have a sizable impact on the electronic properties of the compounds. The presence of the phosphaalkene unit induces a decrease of the HOMO–LUMO gap relative to reference phosphole‐containing π systems that lack a P?C substituent. 相似文献