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排序方式: 共有7472条查询结果,搜索用时 31 毫秒
1.
Gómez M. J. Marklund P. Strombergsson D. Castejón C. García-Prada J. C. 《Experimental Techniques》2021,45(1):1-12
Experimental Techniques - In the last years, the wind industry has increased in a large scale. A wind turbine out of service leeds to high costs due to both maintenance and repair costs and the... 相似文献
2.
Reversible Activation of Water by an Air- and Moisture-Stable Frustrated Rhodium Nitrogen Lewis Pair
Dr. María Carmona Dr. Joaquina Ferrer Dr. Ricardo Rodríguez Dr. Vincenzo Passarelli Prof. Dr. Fernando J. Lahoz Dr. Pilar García-Orduña Dr. Laura Cañadillas-Delgado Prof. Dr. Daniel Carmona 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(60):13665-13670
[Cp*Rh(κ3N,N′,P- L )][SbF6] (Cp*=C5Me5), bearing a guanidine-derived phosphano ligand L , behaves as a “dormant” frustrated Lewis pair and activates H2 and H2O in a reversible manner. When D2O is employed, a facile H/D exchange at the Cp* ring takes place through sequential C(sp3)−H bond activation. 相似文献
3.
Dr. Lorena García-Hevia Dr. Manuel Bañobre-López Dr. Juan Gallo 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(2):431-441
Manganese-based nanostructured contrast agents (CAs) entered the field of medical diagnosis through magnetic resonance imaging (MRI) some years ago. Although some of these Mn-based CAs behave as classic T1 contrast enhancers in the same way as clinical Gd-based molecules do, a new type of Mn nanomaterials have been developed to improve MRI sensitivity and potentially gather new functional information from tissues by using traditional T1 contrast enhanced MRI. These nanomaterials have been designed to respond to biological environments, mainly to pH and redox potential variations. In many cases, the differences in signal generation in these responsive Mn-based nanostructures come from intrinsic changes in the magnetic properties of Mn cations depending on their oxidation state. In other cases, no changes in the nature of Mn take place, but rather the nanomaterial as a whole responds to the change in the environment through different mechanisms, including changes in integrity and hydration state. This review focusses on the chemistry and MR performance of these responsive Mn-based nanomaterials. 相似文献
4.
Dr. Antonio M. Rodríguez Dr. Pilar Prieto Prof. Antonio de la Hoz Prof. Ángel Díaz-Ortiz D. Raúl Martín Prof. José I. García 《ChemistryOpen》2015,4(3):308-317
The aim of this work was to determine the parameters that have decisive roles in microwave-assisted reactions and to develop a model, using computational chemistry, to predict a priori the type of reactions that can be improved under microwaves. For this purpose, a computational study was carried out on a variety of reactions, which have been reported to be improved under microwave irradiation. This comprises six types of reactions. The outcomes obtained in this study indicate that the most influential parameters are activation energy, enthalpy, and the polarity of all the species that participate. In addition to this, in most cases, slower reacting systems observe a much greater improvement under microwave irradiation. Furthermore, for these reactions, the presence of a polar component in the reaction (solvent, reagent, susceptor, etc.) is necessary for strong coupling with the electromagnetic radiation. We also quantified that an activation energy of 20–30 kcal mol−1 and a polarity (μ) between 7–20 D of the species involved in the process is required to obtain significant improvements under microwave irradiation. 相似文献
5.
Antoine Busseau Dr. Carmen Villegas Dr. Sylvie Dabos‐Seignon Dr. Clément Cabanetos Prof. Piétrick Hudhomme Dr. Stéphanie Legoupy 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(25):8452-8456
New penta(organo)fullerenes donor–acceptor systems bearing five tetrathiafulvalene recognition units have been synthesized to promote self‐assemblies similar in appearance to shuttlecocks nested into each other thanks to the conical host cavity created around the fullerene together with the π–π and electronic interactions. 相似文献
6.
Highly Phosphorescent Crystals of Square‐Planar Platinum Complexes with Chiral Organometallic Linkers: Homochiral versus Heterochiral Arrangements,Induced Circular Dichroism,and TD‐DFT Calculations 下载免费PDF全文
Dr. Hugo Sesolis Dr. Julien Dubarle‐Offner Dr. Carmen K. M. Chan Emmanuel Puig Geoffrey Gontard Pierre Winter Prof. Andrew L. Cooksy Prof. Vivian W. W. Yam Dr. Hani Amouri 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(24):8032-8037
A novel class of chiral luminescent square‐planar platinum complexes with a π‐bonded chiral thioquinonoid ligand is described. Remarkably the presence of this chiral organometallic ligand controls the aggregation of this square planar luminophor and imposes a homo‐ or hetero‐chiral arrangement at the supramolecular level, displaying non‐covalent Pt–Pt and π–π interactions. Interestingly these complexes are highly luminescent in the crystalline state and their photophysical properties can be traced to their aggregation in the solid state. A TD‐DFT calculation is obtained to rationalize this unique behavior. 相似文献
7.
8.
Inside Cover: Stereoselective Synthesis of 1,3‐Diaminotruxillic Acid Derivatives: An Advantageous Combination of CH‐ortho‐Palladation and On‐Flow [2+2]‐Photocycloaddition in Microreactors (Chem. Eur. J. 1/2016) 下载免费PDF全文
9.
Experimental and Theoretical Studies on the Rearrangement of 2‐Oxoazepane α,α‐Amino Acids into 2′‐Oxopiperidine β2,3,3‐Amino Acids: An Example of Intramolecular Catalysis 下载免费PDF全文
Dr. Diego Núñez‐Villanueva Dr. M. Ángeles Bonache Laura Lozano Dr. Lourdes Infantes Prof. José Elguero Prof. Ibon Alkorta Prof. M. Teresa García‐López Dr. Rosario González‐Muñiz Dr. Mercedes Martín‐Martínez 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(6):2489-2500
Enantiopure β‐amino acids represent interesting scaffolds for peptidomimetics, foldamers and bioactive compounds. However, the synthesis of highly substituted analogues is still a major challenge. Herein, we describe the spontaneous rearrangement of 4‐carboxy‐2‐oxoazepane α,α‐amino acids to lead to 2′‐oxopiperidine‐containing β2,3,3‐amino acids, upon basic or acid hydrolysis of the 2‐oxoazepane α,α‐amino acid ester. Under acidic conditions, a totally stereoselective synthetic route has been developed. The reordering process involved the spontaneous breakdown of an amide bond, which typically requires strong conditions, and the formation of a new bond leading to the six‐membered heterocycle. A quantum mechanical study was carried out to obtain insight into the remarkable ease of this rearrangement, which occurs at room temperature, either in solution or upon storage of the 4‐carboxylic acid substituted 2‐oxoazepane derivatives. This theoretical study suggests that the rearrangement process occurs through a concerted mechanism, in which the energy of the transition states can be lowered by the participation of a catalytic water molecule. Interestingly, it also suggested a role for the carboxylic acid at position 4 of the 2‐oxoazepane ring, which facilitates this rearrangement, participating directly in the intramolecular catalysis. 相似文献
10.