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61.
Cover Picture: Insertion of a Single‐Molecule Magnet inside a Ferromagnetic Lattice Based on a 3D Bimetallic Oxalate Network: Towards Molecular Analogues of Permanent Magnets (Chem. Eur. J. 6/2014)
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62.
Insertion of a Single‐Molecule Magnet inside a Ferromagnetic Lattice Based on a 3D Bimetallic Oxalate Network: Towards Molecular Analogues of Permanent Magnets
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Dr. Miguel Clemente‐León Prof. Eugenio Coronado Prof. Carlos J. Gómez‐García Dr. Maurici López‐Jordà Dr. Agustín Camón Ana Repollés Dr. Fernando Luis 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(6):1669-1676
The insertion of the single‐molecule magnet (SMM) [MnIII(salen)(H2O)]22+ (salen2?=N,N′‐ethylenebis‐(salicylideneiminate)) into a ferromagnetic bimetallic oxalate network affords the hybrid compound [MnIII(salen)(H2O)]2[MnIICrIII(ox)3]2 ? (CH3OH) ? (CH3CN)2 ( 1 ). This cationic Mn2 cluster templates the growth of crystals formed by an unusual achiral 3D oxalate network. The magnetic properties of this hybrid magnet are compared with those of the analogous compounds [MnIII(salen)(H2O)]2[ZnIICrIII(ox)3]2 ? (CH3OH) ? (CH3CN)2 ( 2 ) and [InIII(sal2‐trien)][MnIICrIII(ox)3] ? (H2O)0.25 ? (CH3OH)0.25 ? (CH3CN)0.25 ( 3 ), which are used as reference compounds. In 2 it has been shown that the magnetic isolation of the Mn2 clusters provided by their insertion into a paramagnetic oxalate network of CrIII affords a SMM behavior, albeit with blocking temperatures well below 500 mK even for frequencies as high as 160 kHz. In 3 the onset of ferromagnetism in the bimetallic MnIICrIII network is observed at Tc=5 K. Finally, in the hybrid compound 1 the interaction between the two magnetic networks leads to the antiparallel arrangement of their respective magnetizations, that is, to a ferrimagnetic phase. This coupling induces also important changes on the magnetic properties of 1 with respect to those of the reference compounds 2 and 3 . In particular, compound 1 shows a large magnetization hysteresis below 1 K, which is in sharp contrast with the near‐reversible magnetizations that the SMMs and the oxalate ferromagnetic lattice show under the same conditions. 相似文献
63.
Gonzalo Abellán Jose A. Carrasco Eugenio Coronado Helena Prima-García 《Journal of Sol-Gel Science and Technology》2014,70(2):292-299
Pure and highly crystalline FeNi3 alloy nanoparticles (NPs) were synthesized via sol–gel route with benzyl alcohol, using hydrazine as a reduction reagent without the usage of additional surfactant molecules nor further annealing processes. The structural studies revealed that the particle size is of ca. 200 nm, whose structure consisted on aggregation of small crystallites of about 13 nm. The magnetic properties of the as-synthesized NPs were similar to the bulk with a saturation magnetization of 95 emu g?1. Moreover, the coercive field was ca. 50 G, exhibiting a M r /M s ratio of 0.03, indicative of soft ferromagnetism. The electrical transport in the temperature range 2–300 K exhibits a typical ferromagnetic metallic behaviour. Finally, similar FeNi3 NPs were synthesized in EtOH/H2O mixtures in the presence of sodium dodecyl sulphate molecules as surfactant for comparative purposes, exhibiting a typical half hard magnetic behaviour, highlighting the interest of the reported benzylic route. 相似文献
64.
Dr. Luka Ðorđević Cataldo Valentini Dr. Nicola Demitri Cécile Mézière Magali Allain Prof. Dr. Marc Sallé Dr. Andrea Folli Prof. Dr. Damien Murphy Samuel Mañas-Valero Prof. Dr. Eugenio Coronado Prof. Dr. Davide Bonifazi 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(10):4135-4143
Herein we report an efficient synthesis to prepare O-doped nanographenes derived from the π-extension of pyrene. The derivatives are highly fluorescent and feature low oxidation potentials. Using electrooxidation, crystals of cationic mixed-valence (MV) complexes were grown in which the organic salts organize into face-to-face π-stacks, a favorable solid-state arrangement for organic electronics. Variable-temperature electron paramagnetic resonance (EPR) measurements and relaxation studies suggest a strong electron delocalization along the longitudinal axis of the columnar π-stacking architectures. Electric measurements of single crystals of the MV salts show a semiconducting behavior with a remarkably high conductivity at room temperature. These findings support the notion that π-extension of heteroatom-doped polycyclic aromatic hydrocarbons is an attractive approach to fabricate nanographenes with a broad spectrum of semiconducting properties and high charge mobilities. 相似文献
65.
Microbial biosynthesis of hydrocarbon from CO2 reduction driven by electron uptake process from the cathodic electrode has gained intensive attention in terms of potential industrial application. However, a lack of a model system for detailed studies on the mechanism of the CO2 reduction hinders the improvement in efficiency for microbial electrosynthesis. Here, we examined the mechanism of microbial CO2 reduction at the cathode by a well‐described microbe for extracellular electron uptake, Shewanella oneidensis MR‐1, capable of reducing gaseous CO2 to produce formic acid. Using whole‐cell electrochemical assay, we observed stable cathodic current production at ?0.65 V vs Ag/AgCl KCl sat. associated with the introduction of CO2. The observed cathodic current was enhanced by the addition of 4 μM riboflavin, which specifically accelerates the electron uptake process of MR‐1 by the interaction to its outer‐membrane c‐type cytochromes. The significant impact of an uncoupler agent and a mutant strain of MR‐1 lacking sole F‐type ATPase suggested the importance of proton import to the cytoplasm for the cathodic CO2 reduction. The present data suggest that MR‐1 potentially serves as a model system for microbial electrosynthesis from CO2. 相似文献
66.
Meccanica - The work investigates the static pull-in instability of electrostatically actuated tweezers with tubular electrodes. At a critical voltage, named pull-in voltage, the attraction force... 相似文献
67.
Ph. Quevauviller G. U. Fortunati M. Filippelli F. Baldi M. Bianchi H. Muntau 《应用有机金属化学》1996,10(7):537-544
The results are presented of an interlaboratory study on methylmercury (MeHg) in sediment carried out by a group of European laboratories within the framework of a project managed by the EC Standards, Measurements and Testing Programme (formerly BCR). The aim of this exercise was to evaluate the performance of current methods used for MeHg determination in sediment in order to improve the state-of-the-art prior to the certification of a candidate reference material. The paper describes the organization of the interlaboratory study, the preparation of the sediment material used, the techniques evaluated and the results obtained by the participating laboratories. The outcome of the collaborative project showed that certification could be contemplated, providing that certain analytical techniques were optimized, especially with regard to extraction methods. 相似文献
68.
Marta Giamberini Eugenio Amendola Cosimo Carfagna 《Macromolecular rapid communications》1995,16(2):97-105
By reacting a rigid rod epoxy terminated molecule (p-bis(2,3-epoxypropoxy)-α-methylstilbene) with an aliphatic carboxylic acid (decanedioic acid), a lightly crosslinked liquid crystalline network is obtained. This network exhibits a smectic-like phase. While the mesophasic structure resulted “frozen” by the crosslinks in the case of higly crosslinked liquid crystalline epoxy resins, in this case a reversible transition from the liquid crystalline to the isotropic phase is observed. Moreover, while curing the same rigid rod epoxy molecule with amines resulted in a thermoset with a nematic structure, in this case a more ordered mesophase can be obtained. Preliminary results show that it is possible to orient macroscopically the mesogenic chains by stretching thin films above the glass transition temperature (Tg) and then quickly cooling down to the glassy state. This makes this material very attractive in the field of optical applications. 相似文献
69.
Effect of salinity on petroleum biodegradation 总被引:1,自引:0,他引:1
G. Mille M. Almallah M. Bianchi F. van Wambeke J. C. Bertrand 《Fresenius' Journal of Analytical Chemistry》1991,339(10):788-791
Summary The biodegradation of Ashtart crude oil by a mixed bacterial community (EH1) isolated from a marine sediment was investigated in varying concentration of sodium chloride (0 to 2 mol/l). Each fraction of Ashtart crude oil was biodegraded after a 30 day incubation period for a NaCl concentration equivalent to the one of seawater (0.4 mol/l). Saturates were more readily degraded than aromatics. The amount of oil degraded increased initially with increasing salt concentrations to a maximum level for 0.4 mol/l NaCl concentration. Thereafter the amount of oil degraded decreased with increasing salt concentrations. The polar fraction increased for the 0.4 to 1.4 mol/l NaCl concentration range. Asphaltenes were only slightly degraded (10%) for a NaCl concentration equivalent to the one of seawater (0.4 mol/l). NaCl concentrations seemed to affect the relative biodegradation of pristane and phytane. GC, UV fluorescence and FTIR techniques were used to study the evolution of each fraction of Ashtart crude oil. 相似文献
70.
Tao Zheng Prof. Dr. Juan M. Clemente‐Juan Prof. Dr. Jing Ma Prof. Dr. Lin Dong Dr. Song‐Song Bao Dr. Jian Huang Prof. Dr. Eugenio Coronado Prof. Dr. Li‐Min Zheng 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(48):16394-16402
Two cobalt phosphonates, [Co2(2,2′‐bpy)2(H2O)(pbtcH)] ( 1 ) and [Co2(H2O)(pbtcH)(phen)2] ( 2 ; pbtcH5=5‐phosphonatophenyl‐1,2,4‐tricarboxylic acid, 2,2′‐bpy=2,2′‐bipyridine, phen=1,10‐phenanthroline), with layer structures are reported. Compound 1 contains O‐C‐O and O‐P‐O bridged tetramers of Co4, which are further connected by pbtcH4? units to form a layer. In compound 2 , the cobalt tetramers made up of water‐bridged Co2 dimers and O‐P‐O linkages are connected into a layer by pbtcH4? units. Upon dehydration, compounds 1 and 2 experience single‐crystal‐to‐single‐crystal (SC–SC) structural transformations to form [Co2(2,2′‐bpy)2(pbtcH)] ( 1 a ) and [Co2(pbtcH)(phen)2] ( 2 a ), respectively. The process is reversible in each case. Notably, a breathing effect is observed for 1 , accompanied by pore opening and closing due to the reorientation of the coordinated 2,2′‐bpy molecules. The transformation was also monitored by in situ IR measurements. Magnetic studies reveal that antiferromagnetic interactions are mediated between the magnetic centers in compounds 1 and 1 a , whereas ferromagnetic interactions are dominant in compound 2 . 相似文献