Synthesis and characterization of TTF-type precursors for the construction of conducting and magnetic molecular materials

New TTF precursors for the construction of conducting and magnetic materials have been synthesized by using the palladium-catalyzed cross-coupling reaction between a mono- or a bis(trialkylstannyl)tetrathiafulvalene and a series of heteroaryl halides. The redox potential and some crystallographic data of these new building blocks are presented and discussed.     

New Metal Oxamates as Precursors of Low-Dimensional Heterobimetallics

The goal of this work was to synthesize new molecular bricks which could be used as precursors of heterobimetallic low-dimensional compounds. Along this line, four compounds have been synthesized and structurally characterized, namely (NBu(4))(2)[Ni(Cl(2)opba)] (1), (NBu(4))(2)[Cu(Cl(2)opba)] (2), (NBu(4))(5)[Mn(Cl(2)opba)(DMSO)(2)](4) (3), and Cu(en)(2)[Mn(Cl(2)opba)(H(2)O)(2)](2).2DMSO (4), with Cl(2)opba = (4,5-dichloro-o-phenylene)bis(oxamato), NBu(4) = tetra-n-butylammonium, en = ethylenediamine, and DMSO = dimethyl sulfoxide. Compounds 1 and 2 are isostructural; they crystallize in the monoclinic system, space group C2/c, Z = 4, with a = 18.708(2) ?, b = 17.525(2) ?, c = 14.763(9) ?, and beta = 92.03(4) degrees for 1 and a = 18.928(2) ?, b = 17.634(2) ?, c = 14.704(9) ?, and beta = 92.38(3) degrees for 2. 3 crystallizes in the tetragonal system, space group P&fourmacr;2(1)c, Z = 2, with a = 26.295(10) ? and c = 12.342(7) ?. The structure shows a random occupation of the metal site by Mn(III) and Mn(II) ions in 3/4 and 1/4 ratios, respectively. 4 crystallizes in the triclinic system, space group P&onemacr;, Z = 1, with a = 7.066(7) ?, b = 11.844(1) ?, c = 14.292(5) ?, alpha = 105.64(2) degrees, beta = 97.67(5) degrees, and gamma = 102.13(3) degrees. The structure consists of Mn(III)Cu(II)Mn(III) trinuclear species, with Cu-O-Mn bridges involving oxygen atoms of the oxamato groups already linked to the metal atom. The magnetic properties of compounds 1-4 have been investigated and quantitatively interpreted. For 3, this magnetic investigation has been performed on a single crystal, which allows us to determine unambiguously the sign of the axial zero-field splitting parameter for the Mn(III) ion. The potentialities of these new molecular bricks have been discussed.     

Ferromagnetic versus antiferromagnetic exchange interactions in tetrathiafulvalene-based 3d/4f heterobimetallic complexes

(TTF-salphen)M compounds (TTF-salphen(2-)=4,5-bis(propylthio)tetrathiafulvalene-N,N'-phenylenebis(salicylideneimine) dianion; M=Cu(II) and Ni(II)) have been treated with Ln(hfac)(3)·2H(2)O precursors (hfac(-)=1,1,1,5,5,5-hexafluoroacetylacetonate anion; Ln=Gd(III), Tb(III), and Dy(III)) to elaborate unprecedented 3d/4f TTF-based heterobimetallic complexes of formula [(TTF-salphen)MLn(hfac)(3)]. All the structures of these compounds have been resolved by X-ray diffraction on single crystals. The structures of these complexes are formed by a TTF-salphen(2-) ligand coordinated to the 3d metal ions in the inert tetradentate N(2)O(2) site. The Ln(hfac)(3) fragment is coordinated to the (TTF-salphen)M one through the two phenolate bridges. Even if the complexes are similar in both Cu(II) and Ni(II) families, the crystal packing is different. In the first case, dimers of TTF-salphen(2-) donors constitute the organic network. In the other case, a reminiscent organic network is observed with S···S contacts. The photophysical properties of [(TTF-salphen)CuDy(hfac)(3)] (3) in chloroform solution highlight the redshift of the TTF→salphen charge transfer (400 cm(-1)) relative to the analogue excitations in (TTF-salphen)Cu, which attest to the stability of these structures in solution. Static magnetic measurements have allowed us to quantify the ferromagnetic interactions (J=+1.29 cm(-1)) between Cu(II) and Gd(III) in the [(TTF-salphen)CuGd(hfac)(3)] complex. Finally, an empirical method that consists of the comparisons of the magnetic properties of [(TTF-salphen)CuTb(hfac)(3)] with [(TTF-salphen)NiTb(hfac)(3)] and [(TTF-salphen)CuDy(hfac)(3)] with [(TTF-salphen)NiDy(hfac)(3)] has established that ferromagnetic interactions take place between Cu(II) and Tb(III) ions, whereas unusual antiferromagnetic interactions have been identified between Cu(II) and Dy(III) ions.     

Two- and three-dimensional comparative study of heat transfer and pressure drop characteristics of nanofluids flow through a ventilated cubic cavity (part I: Newtonian nanofluids)

Journal of Thermal Analysis and Calorimetry - Through this paper, three-dimensional fluid flow and heat transfer of Al2O3 nanofluid within ventilated enclosures was taken into consideration....     

Surface plasmon resonance immunosensor for bacteria detection

This work describes an approach for the development of two bacteria biosensors based on surface plasmon resonance (SPR) technique. The first biosensor was based on functionalized gold substrate and the second one on immobilized gold nanoparticles. For the first biosensor, the gold substrate was functionalized with acid-thiol using the self-assembled monolayer technique, while the second one was functionalized with gold nanoparticles immobilized on modified gold substrate. A polyclonal anti-Escherichia coli antibody was immobilized for specific (E. coli) and non-specific (Lactobacillus) bacteria detection. Detection limit with a good reproducibility of 10⁴ and 10³ cfu mL⁻¹ of E. coli bacteria has been obtained for the first biosensor and for the second one respectively. A refractive index variation below 5 × 10⁻³ due to bacteria adsorption is able to be detected. The refractive index of the multilayer structure and of the E. coli bacteria layer was estimated with a modeling software.     

Structural properties of the trimetallic acetylide complex [{Ru(CO)2(η5C5H5)}3(η1:η1:η2:-CC)]+

The purpose of this Note is the study of the structure and fluxional behavior of the complex [{Ru(CO)₂(η⁵C₅H₅)}₃(η¹:η¹:η²:-CC)]⁺, using density functional methods. The molecular geometry of this complex will be optimized, the transition state (TS) of the fluxional process will be determined and the origin of the energy barrier will be analyzed.     

Étude de l?adhérence des joncs et des plats composite avec le béton par flexion (beam test)

The Near Surface Mounted (NSM) technique has been used in recent years for the strengthening of reinforced concrete beams. It involves the insertion of strips or rods of polymers reinforced with carbon fiber (CFRP) in the groove made previously in the concrete cover of corresponding surfaces, filled with epoxy adhesive for fixation. In order to characterize the bond behavior of the laminate and rods to concrete, an experimental work of pullout-bending tests was carried out. The pullout force at the laminate and the slip at the free and loaded end were measured. The influences of the concrete strength, the strength of the bond, and bond length on the bonding behavior between the three materials concrete, epoxy adhesive and CFRP were analyzed.     

Operateurs essentiellement reguliers dans les espaces de Banach

Given a closed operatorA acting in a Banach spaceX, we define the regular (respectively the essentialy regular) spectrum σ _r (A) (respectively σ _e,r (A)) ofA. We prove that σ _r (A) and σ _e,r (A) are a closed subsets of the classical spectrum σ(A) ofA. Morever ifA is bounded we prove that σ _r (A) and σ _e,r (A)) satisfies the spectral mapping theorem.     

Nonconvex-valued impulsive functional differential inclusions with variable times

We use the Schaefer fixed-point theorem, combined with the Bressan-Colombo selection theorem for lower-semicontinuous multivalued operators with nonempty closed and decomposable values, for the investigation of the existence of solutions for first-and second-order impulsive functional differential inclusions with variable times. Published in Neliniini Kolyvannya, Vol. 10, No. 4, pp. 443–463, October–December, 2007.