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51.
Llusar R Uriel S Vicent C Clemente-Juan JM Coronado E Gómez-García CJ Braïda B Canadell E 《Journal of the American Chemical Society》2004,126(38):12076-12083
A trinuclear cluster complex containing the Mo(3)S(7) central unit coordinated to dithiolate ligands, in particular the organic dmit (1,3-dithia-2-thione-4,5-dithiolate) anion, has been used to prepare a single-component molecular conductor formed by the threefold symmetry magnetic building block Mo(3)S(7)(dmit)(3) (1). The [Mo(3)S(7)(dmit)(3)](2)(-) ([1](2)(-)) diamagnetic anion forms dimers by interaction between the electrophilic cluster axial sulfur atoms and the sulfur atoms of the outer dithiolate ligand. Additional contacts between adjacent dmit ligands result in chain formation. The two-electron oxidation of [1](2)(-) yields to a three-dimensional molecular solid formed by neutral Mo(3)S(7)(dmit)(3) (1) units with partially filled molecular orbitals, which exhibits sizable intermolecular electronic interactions together with a significant electron delocalization. It also contains large open channels. The interactions responsible for the conducting properties have been identified using a first-principle DFT approach and the calculated electronic structure has allowed us to model the magnetic behavior of the material with two competing antiferromagnetic interactions to produce a spin-frustrated extended network. The potential of this Mo(3)S(7) cluster complex to be modified together with the capability of filling the open channels with doping species paves the way to an entirely new set of molecular conductors and/or magnets. 相似文献
52.
Clemente-León M Coronado E Galán-Mascarós JR Gómez-García CJ Canadell E 《Inorganic chemistry》2000,39(23):5394-5397
53.
Marta?Canadell àlex?HaroEmail authorView authors OrcID profile 《Journal of Nonlinear Science》2017,27(6):1829-1868
We present several algorithms for computing normally hyperbolic invariant tori carrying quasi-periodic motion of a fixed frequency in families of dynamical systems. The algorithms are based on a KAM scheme presented in Canadell and Haro (J Nonlinear Sci, 2016. doi: 10.1007/s00332-017-9389-y), to find the parameterization of the torus with prescribed dynamics by detuning parameters of the model. The algorithms use different hyperbolicity and reducibility properties and, in particular, compute also the invariant bundles and Floquet transformations. We implement these methods in several 2-parameter families of dynamical systems, to compute quasi-periodic arcs, that is, the parameters for which 1D normally hyperbolic invariant tori with a given fixed frequency do exist. The implementation lets us to perform the continuations up to the tip of the quasi-periodic arcs, for which the invariant curves break down. Three different mechanisms of breakdown are analyzed, using several observables, leading to several conjectures. 相似文献
54.
Biaso F Geoffroy M Canadell E Auban-Senzier P Levillain E Fourmigué M Avarvari N 《Chemistry (Weinheim an der Bergstrasse, Germany)》2007,13(19):5394-5400
The synthesis and characterization of two ortho-dimethyltetrathiafulvalene (o-DMTTF)-based rigid dimers containing dimethylsilicon (Me(2)Si) or dimethylgermanium (Me(2)Ge) linkers are described. Single-crystal X-ray analysis reveals planar geometry for the central 1,4-disilicon or 1,4-digermanium six-membered rings. DFT calculations provide optimized conformations in agreement with the experimental ones, and also emphasize the role of the heteroatomic linkers in the conjugation between the two redox active units. Cyclic voltammetry measurements show sequential oxidation into radical cation, and then dication species. Solution EPR measurements on the radical-cation species indicate full delocalization of the unpaired electron over both electroactive TTF units, with an associated coupling of 0.42 G with twelve equivalent protons. DFT calculations afford fully planar geometry for the radical-cation species and confirm the experimental isotropic coupling constant. Single-crystal X-ray analyses of two charge-transfer compounds obtained upon chemical oxidation, formulated as [(Me(2)Si)(2)(o-DMTTF)(2)].1/2[TCNQ].1/2[TCNQF(4)] and [(Me(2)Ge)(2)(o-DMTTF)(2)].[TCNQ], demonstrate the occurrence of genuine mixed-valence radical-cation species, as well as a three-dimensional network of short S...S intermolecular contacts. Temperature-dependent conductivity measurements demonstrate semiconducting behavior for both charge-transfer compounds, with an increase of the absolute value of the conductivity upon applying external pressure. Band structure calculations reveal peculiar pseudo-two-dimensional electronic structures, also confirming electronic interactions through SiMe(2) and GeMe(2) bridges. 相似文献
55.
56.
J. Canadell A. Mantecón V. Cádiz 《Journal of polymer science. Part A, Polymer chemistry》2007,45(10):1980-1992
A new bis‐spiroorthoester‐containing monomer, bis[(1,4,6‐trioxaspiro‐[4.4]‐nonan‐2‐yl)‐methyl] 2‐[10‐(9,10‐dihydro‐9‐oxa‐10‐phosphaphenantrene‐10‐oxide‐10‐yl)] maleate (SOE‐DOPOMA), was synthesized with good yields by an esterification reaction with a hydroxylated spiroorthoester (2‐hydroxymethyl‐1,4,6‐trioxaspiro‐[4.4]‐nonane) and a phosphorus‐containing diacid {2‐[10‐(9,10‐dihydro‐9‐oxa‐10‐phosphaphenantrene‐10‐ oxide‐10‐yl)] maleic acid}, both of which were previously synthesized. SOE‐DOPOMA was characterized with 1H, 13C, and 31P NMR spectroscopy. This new spiroorthoester was crosslinked with ytterbium triflate as a cationic initiator. A mixture of SOE‐DOPOMA and diglycidyl ether of bisphenol A was also crosslinked under the same conditions. The curing was studied with differential scanning calorimetry and monitored with Fourier transform infrared spectroscopy. The materials were characterized with differential scanning calorimetry, thermogravimetric analysis, and thermodynamomechanical analysis. The shrinkage effect on cationic crosslinking was assessed with gas pycnometry, and the flame‐retardant properties were determined with limiting oxygen index measurements. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 1980–1992, 2007. 相似文献
57.
J. Canadell A. Mantecn V. Cdiz 《Journal of polymer science. Part A, Polymer chemistry》2006,44(16):4722-4730
A new phosphorus‐containing spiroorthoester, (1,4,6‐trioxaspiro [4,4] nonan‐2‐yl)‐methyl 3‐[10‐(9,10‐dihydro‐9‐oxa‐9‐phosphaphenanthrene‐10‐oxide)]‐propanoate (SOE‐P), was synthesized under microwave irradiation with a short reaction time (1 h), because classical thermal heating did not lead to the desired product. The structure of the new monomer was confirmed by 1H, 13C, and 31P. SOE‐P was homopolymerized and copolymerized with phenylglycidyl ether with ytterbium triflate as a cationic initiator in DSC experiments. These reactions were monitored by FTIR/ATR, and the formation of poly(ether‐ester)s with a pendant bulky phosphorylated group was shown. © 2006Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 4722–4730, 2006 相似文献
58.
D. Vignolles A. Audouard R. B. Lyubovskii M. Nardone E. Canadell E. I. Zhilyaeva R. N. Lyubovskaya 《The European Physical Journal B - Condensed Matter and Complex Systems》2008,66(4):489-495
Pressure dependence of the Shubnikov-de Haas (SdH)
oscillations spectra of the quasi-two dimensional organic metal
(ET)8[ Hg4Cl12(C6H5Br)2] have been studied up
to 1.1 GPa in pulsed magnetic fields of up to 54 T. According to
band structure calculations, its Fermi surface can be regarded as
a network of compensated orbits. The SdH spectra exhibit many
Fourier components typical of such a network, most of them being
forbidden in the framework of the semiclassical model. Their
amplitude remains large in all the pressure range studied which
likely rules out chemical potential oscillation as a dominant
contribution to their origin, in agreement with recent
calculations relevant to compensated Fermi liquids. In addition to
a strong decrease of the magnetic breakdown field and effective
masses, the latter being likely due to a reduction of the strength
of electron correlations, a sizeable increase of the scattering
rate is observed as the applied pressure increases. This latter
point, which is at variance with data of most charge transfer
salts is discussed in connection with pressure-induced features of
the temperature dependence of the zero-field interlayer
resistance. 相似文献
59.
The electronic structure of the recently reported ternary nitride Ca(2)GeN(2) has been studied by means of first-principles density functional calculations. The relatively short nonbonded Ge...Ge contacts along the direction approximately perpendicular to the plane of the bent GeN(2) units confer a large dispersion to the energy bands based on the antibonding pi-type level of GeN(2). This feature as well as the smaller but non-negligible interactions along the perpendicular directions suggests that this material, despite being built from discrete units, may exhibit a metallic behavior. This study suggests that the nature of the alkaline-earth atom has a crucial influence on the electrical conductivity of this type of phase. 相似文献
60.