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201.
Dr. Julie Massaad Dr. Jean‐Claude Micheau Dr. Christophe Coudret Dr. Charles Louis Serpentini Dr. Gonzalo Guirado 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(37):12435-12445
A thermally irreversible dithienylethene (DTE) photochrom can be turned into a thermally reversible one in presence of CuII triflate. A ring opening (DTEC closed→DTEO open) occurs through the formation of a copper‐containing fast transient intermediate. Stopped‐flow experiments monitored at 410 and 780 nm have allowed to show that the stoichiometry of this intermediate is DTE/Cu=1:1. At longer monitoring times (i.e., several seconds after mixing), the intermediate undergoes a slow decay while the residual DTEC closed form opens. A joint detailed kinetic and electrochemical analysis has unveiled a proton catalysis scenario in which electron transfer between DTEC and CuII, ligand exchange, protonation‐deprotonation equilibria of the cation radicals and ring opening are embedded into two main reaction cycles. At the beginning of the reaction, CuII is reduced into CuI and DTE is degraded without ring opening. Then, as the reaction progresses, the triflic acid released from the CuII reduction switches‐on a propagation cycle during which ring opens without any more CuII consumption. Cyclic voltammetry, spectro‐electrochemical measurements, delayed photocoloration experiments in presence of CuII and acid–base additions have confirmed the main features of the proton catalysis. 相似文献
202.
Miguel Espinosa Prof. Dr. Gonzalo Blay Prof. Dr. Luz Cardona Prof. Dr. José R. Pedro 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(44):14861-14866
The asymmetric conjugate addition of malonate esters to α,β‐unsaturated N‐sulfonyl imines is catalyzed by PyBOX/La(OTf)3 complexes in the presence of 4 Å MS. The reaction gives the corresponding E enamines bearing a stereogenic center at the allylic position with good yields and enantiomeric ratios up to 97:3. This reaction provides a synthetic entry to chiral δ‐aminoesters and piperidones. 相似文献
203.
Gonzalo Cortazar Lorenzo Naranjo Felipe Sainz 《European Journal of Operational Research》2021,288(2):634-647
The Least-Squares Monte Carlo Method (LSM) has become the standard tool to solve real options modeled as an optimal switching problem. The method has been shown to deliver accurate valuation results under complex and high dimensional stochastic processes; however, the accuracy of the underlying decision policy is not guaranteed. For instance, an inappropriate choice of regression functions can lead to noisy estimates of the optimal switching boundaries or even continuation/switching regions that are not clearly separated. As an alternative to estimate these boundaries, we formulate a simulation-based method that starts from an initial guess of them and then iterates until reaching optimality. The algorithm is applied to a classical mine under a wide variety of underlying dynamics for the commodity price process. The method is first validated under a one-dimensional geometric Brownian motion and then extended to general Markovian processes. We consider two general specifications: a two-factor model with stochastic variance and a rich jump structure, and a four-factor model with stochastic cost-of-carry and stochastic volatility. The method is shown to be robust, stable, and easy-to-implement, converging to a more profitable strategy than the one obtained with LSM. 相似文献
204.
Yongzhen Zhang Marcos Gmez‐Redondo Gonzalo Jimnez‐Oss Ana Arda Herman S. Overkleeft Gijsbert A. van der Marel Jesús Jimnez‐Barbero Jeroen D. C. Code 《Angewandte Chemie (International ed. in English)》2020,59(31):12746-12750
Galactosaminogalactan (GAG) is a prominent cell wall component of the opportunistic fungal pathogen Aspergillus fumigatus. GAG is a heteropolysaccharide composed of α‐1,4‐linked galactose, galactosamine and N‐acetylgalactosamine residues. To enable biochemical studies, a library of GAG‐fragments was constructed featuring specimens containing α‐galactose‐, α‐galactosamine and α‐N‐acetyl galactosamine linkages. Key features of the synthetic strategy include the use of di‐tert‐butylsilylidene directed α‐galactosylation methodology and regioselective benzoylation reactions using benzoyl‐hydroxybenzotriazole (Bz‐OBt). Structural analysis of the Gal, GalN and GalNAc oligomers by a combination of NMR and MD approaches revealed that the oligomers adopt an elongated, almost straight, structure, stabilized by inter‐residue H‐bonds, one of which is a non‐conventional C?H???O hydrogen bond between H5 of the residue (i+1) and O3 of the residue (i). The structures position the C‐2 substituents almost perpendicular to the oligosaccharide main chain axis, pointing to the bulk solvent and available for interactions with antibodies or other binding partners. 相似文献
205.
Dr. Feng Wang Jerrik Mielby Dr. Felix Herrmann Richter Dr. Guanghui Wang Dr. Gonzalo Prieto Dr. Takeshi Kasama Dr. Claudia Weidenthaler Hans‐Josef Bongard Prof. Dr. Søren Kegnæs Prof. Dr. Alois Fürstner Prof. Dr. Ferdi Schüth 《Angewandte Chemie (International ed. in English)》2014,53(33):8645-8648
We describe a solid polyphenylene support that serves as an excellent platform for metal‐catalyzed reactions that are normally carried out under homogeneous conditions. The catalyst is synthesized by palladium‐catalyzed Suzuki coupling which directly results in formation of palladium nanoparticles confined to a porous polyphenylene network. The composite solid is in turn highly active for further Suzuki coupling reactions, including non‐activated substrates that are challenging even for molecular catalysts. 相似文献
206.
Highly Enantioselective Copper(I)‐Catalyzed Conjugate Addition of Terminal Alkynes to 1,1‐Difluoro‐1‐(phenylsulfonyl)‐3‐en‐2‐ones: New Ester/Amide Surrogates in Asymmetric Catalysis
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Amparo Sanz‐Marco Andrea García‐Ortiz Prof. Dr. Gonzalo Blay Isabel Fernández Prof. Dr. José R. Pedro 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(3):668-672
A highly enantioselective copper‐catalyzed conjugate alkynylation of monoactivated enones, namely 1,1‐difluoro‐1‐(phenylsulfonyl)‐3‐en‐2‐ones, is described. The reaction products are obtained with good yields and excellent enantioselectivities (from 92 to 99% ee). The β‐alkynylated difluoro(phenylsulfonyl) ketones can be converted into the corresponding β‐alkynylated difluoro‐ and trifluoromethyl ketones, esters and amides. This is the first example on the use of 1,1‐difluoro‐1‐(phenylsulfonyl)‐3‐en‐2‐ones as substrates in an enantioselective reaction, which have been shown to be new ester/amide surrogates. 相似文献
207.
First Highly Efficient and Photostable E and C Derivatives of 4,4‐Difluoro‐4‐bora‐3a,4a‐diaza‐s‐indacene (BODIPY) as Dye Lasers in the Liquid Phase,Thin Films,and Solid‐State Rods
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Gonzalo Duran‐Sampedro Ixone Esnal Prof. Antonia R. Agarrabeitia Dr. Jorge Bañuelos Prieto Dr. Luis Cerdán Prof. Inmaculada García‐Moreno Prof. Angel Costela Prof. Iñigo Lopez‐Arbeloa Prof. María J. Ortiz 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(9):2646-2653
A new library of E‐ and C‐4,4‐difluoro‐4‐bora‐3a,4a‐diaza‐s‐indacene (BODIPY) derivatives has been synthesized through a straightforward protocol from commercially available BODIPY complexes, and a systematic study of the photophysical properties and laser behavior related to the electronic properties of the B‐substituent group (alkynyl, cyano, vinyl, aryl, and alkyl) has been carried out. The replacement of fluorine atoms by electron‐withdrawing groups enhances the fluorescence response of the dye, whereas electron‐donor groups diminish the fluorescence efficiency. As a consequence, these compounds exhibit enhanced laser action with respect to their parent dyes, both in liquid solution and in the solid phase, with lasing efficiencies under transversal pumping up to 73 % in liquid solution and 53 % in a solid matrix. The new dyes also showed enhanced photostability. In a solid matrix, the derivative of commercial dye PM597 that incorporated cyano groups at the boron center exhibited a very high lasing stability, with the laser emission remaining at the initial level after 100 000 pump pulses in the same position of the sample at a 10 Hz repetition rate. Distributed feedback laser emission was demonstrated with organic films that incorporated parent dye PM597 and its cyano derivative. The films were deposited onto quartz substrates engraved with appropriate periodical structures. The C derivative exhibited a laser threshold lower than that of the parent dye as well as lasing intensities up to three orders of magnitude higher. 相似文献
208.
Differences between global radiation UVER (erythemal ultraviolet solar radiation) received under full sun and diffuse radiation received under the shadow of two types of tree are analyzed to check the importance of these components on human exposure to UV radiation. Blue Line spores dosimeters of VioSpor were used for measurement of erythemal dose of UV radiation (able to produce erythema in human skin.) The response profile of these devices is extremely similar to human skin, thus they are suitable to determine and predict the interactions between UV erythema and human skin. Measurements were obtained in relatively clear days from February to December 2009 between 9:30 and 15:30 h. Three dosimeters were placed on a horizontal surface: one in full sun and the other two under the shadow of each tree. Values of UVER in both cases, in full sun and under the shadow of pine and Sauce, were obtained. In addition, the comparison was made between values of dose received in each case and the exposure limits recommended by the International Commission on Non‐Ionizing Radiation Protection (ICNIRP). Finally, average daily irradiance received under the shadow of each tree in comparison with those received in full sun, was also analyzed using two PMA2100 radiometers situated on a horizontal surface. 相似文献
209.
Mathematische Zeitschrift - In the present work we study existence of solutions of fractional Dirichlet problems in the presence of coercive gradient terms with growth comparable and slightly... 相似文献
210.
Perez-de-la-Cruz Gonzalo Eslava-Gomez Guillermina 《Advances in Data Analysis and Classification》2019,13(4):855-876
Advances in Data Analysis and Classification - The purpose of this paper is to illustrate the potential use of discriminant analysis for discrete variables whose dependence structure is assumed to... 相似文献