ACTION DESIMINES SUR LES MONOCHLOROPHOSPHINES: NOUVELLE VOIE D'ACCES A DES CETONES β-PHOSPHORYLEES

Abstract

The reaction of imines 1 with monochlorophosphines leads to β-phosphorylketones obtained in the ketonic 2 or enolic forms 2′. The structure of all obtained products is confirmed by NMR and IR spectroscopy.     

Heterodyne detection for Fiber Bragg Grating sensors

In this paper, we present a Fiber-Bragg-Grating-based temperature sensor. The technique employs heterodyne detection using two Fiber Bragg Gratings. One of the gratings is used as a reference (local oscillator) and the second as a sensing arm. This sensor uses a Folded Mach-Zehnder interferometer. As the temperature changes, the Bragg wavelength of the FBG shifts. The heterodyne detection is used to detect the frequency difference between the reference and sensing signals that is caused by the temperature change. The dynamic range and sensitivity of the sensor were analyzed and presented.     

Physicochemical and rheological properties of thickeners produced from Tunisian clays

Modification of two samples of Tunisian clays of the type of natural smectites with organic derivatives of ammonium salts was studied. The physicochemical properties of the modified products and the possibility of their use as components of lubricating oils were analyzed. Published in Russian in Zhurnal Prikladnoi Khimii, 2006, Vol. 79, No. 3, pp. 387–392. This article was submitted by the authors in English.     

First Synthesis of γ,γ′-Diphosphonylketones and Their Reactivity in the Fischer Reaction

Two synthetic methods leading to the new n , n '-diphosphonylketones 2 and 2 ' are reported. The first method involves the base-catalyzed addition of diethylphosphite to diarylideneketones. The second one utilizes the reaction of triethylphosphite and ethoxydiphenylphosphine with g , g '-bis(dimethylamino)ketone hydrochlorides. On reaction with phenylhydrazine hydrochloride, compounds 2 and 2 ' give the corresponding 2-(phosphonoethyl)3-(phosphonomethyl)indoles 3 . The structure of all obtained products is confirmed by NMR ( 1 H, 31 P, 13 C) and IR spectroscopy.     

Action de 3-hydrazino-2-(N,N-dialkylaminométhyl)propanenitriles sur quelques iminoesters N-fonctionnalisés : synthèse de dérivés triazoliques

Reaction of 3-hydrazino-2-(N,N-dialkylaminomethyl)propanenitriles with a series of N-functionalized iminoesters: Synthesis of triazolic compounds. The reaction of 3-hydrazino-2-(N,N-dialkylaminomethyl)propanenitriles with a series of N-functionalized iminoesters leads to the formation of triazolones and triazoles. The latter, presenting two reactive sites in positions 1 and 6, undergo intramolecular cyclization, to form triazolopyrimidine in good yields.     

Decoration of discretely immobilized cowpea mosaic virus with luminescent quantum dots

This report describes two related methods for decorating cowpea mosaic virus (CPMV) with luminescent semiconductor nanocrystals (quantum dots, QDs). Variants of CPMV are immobilized on a substrate functionalized with NeutrAvidin using modifications of biotin-avidin binding chemistry in combination with metal affinity coordination. For example, using CPMV mutants expressing available 6-histidine sequences inserted at loops on the viral coat protein, we show that these virus particles can be specifically immobilized on NeutrAvidin functionalized substrates in a controlled fashion via metal-affinity coordination. To accomplish this, a hetero-bifunctional biotin-NTA moiety, activated with nickel, is used as the linker for surface immobilization of CPMV (bridging the CPMVs' histidines to the NeutrAvidin). Two linking chemistries are then employed to achieve CPMV decoration with hydrophilic CdSe-ZnS core-shell QDs; they target the histidine or lysine residues on the exterior virus surface and utilize biotin-avidin interactions. In the first scheme, QDs are immobilized on the surface-tethered CPMV via electrostatic attachment to avidin previously bound to the virus particle. In the second strategy, the lysine residues common to each viral surface asymmetric unit are chemically functionalized with biotin groups and the biotinylated CPMV is discretely immobilized onto the substrate via NeutrAvidin-biotin interactions. The biotin units on the upper exposed surface of the immobilized CPMV then serve as capture sites for QDs conjugated with a mixture of avidin and a second protein, maltose binding protein, which is also used for QD-protein conjugate purification. Characterization of the assembled CPMV and QD structures is presented, and the potential uses for protein-coated QDs functionalized onto this symmetrical virion nanoscaffold are discussed.     

A hybrid quantum dot-antibody fragment fluorescence resonance energy transfer-based TNT sensor

We demonstrate the use of luminescent QDs conjugated to antibody fragments to develop solution-phase nanoscale sensing assemblies, based on fluorescence resonance energy transfer (FRET) for the specific detection of the explosive 2,4,6-trinitrotoluene (TNT) in aqueous environments. The hybrid sensor consists of anti-TNT specific antibody fragments attached to a hydrophilic QD via metal-affinity coordination. A dye-labeled TNT analogue prebound in the antibody binding site quenches the QD photoluminescence via proximity-induced FRET. Analysis of the data collected at increasing dye-labeled analogue to QD ratios provided an insight into understanding how the antibody fragments self-assemble on the QD. Addition of soluble TNT displaces the dye-labeled analogue, eliminating FRET and resulting in a concentration-dependent recovery of QD photoluminescence. Sensor performance and specificity were evaluated.     

The effects of surface layers on third harmonic generation from solutions of a nematogenic polymer

Third harmonic generation (THG) is used to study the third-order nonlinear optical properties of nematic and isotropic solutions of poly(1,4-phenylene-2,6-benzobisthiazole) and related small-molecule model compounds. Maker fringe patterns (MFP) obtained using both plane slab and wedge-shaped cells for fundamental wavelengths of 1.542 and 1.907 μm are analyzed in terms of postulated surface layers in the isotropic preparations. The layers are postulated to comprise regions with concentration smaller than for the bulk sample, in which the rod-like chains tend to have their axes parallel to the plane of the surface, creating a negatively birefringent uniaxial nematic layer. The THG with the nematic solution exhibits intensity with polarization components unexpected for the uniaxial nematic symmetry attributed from linear optical properties, along with other unexpected features in the MFP. This behavior is attributed to the effects of surface layers, postulated to exhibit biaxial nematic symmetry, in which the uniaxial nematic symmetry is broken in regions on the scale of a wavelength. This provides for averaging that does not cause departure from the linear optical behavior expected for a uniaxial nematic, but does produce effects on nonlinear optical properties. © 1996 John Wiley & Sons, Inc.     

Multinuclear cytotoxic metallodrugs: physicochemical characterization and biological properties of novel heteronuclear gold-titanium complexes

An unprecedented series of titanocene-gold bi- and trimetallic complexes of the general formula [[(η(5)-C(5)H(5))(μ-η(5):κ(1)-C(5)H(4)(CH(2))(n)PPh(2))TiCl(2)](m)AuCl(x)](q+) (n = 0, 2, or 4; m = 1, x = 1, q = 0 or m = 2, x = 0, q = 1) have been prepared and characterized spectroscopically. The luminescence spectroscopy and photophysics of one of the compounds, [[(η(5)-C(5)H(5))(μ-η(5):κ(1)-C(5)H(4)PPh(2))TiCl(2)](2)Au]PF(6), have been investigated in 2MeTHF solution and in the solid state at 77 and 298 K. Evidence for interfragment interactions based on the comparison of electronic band positions and emission lifetimes, namely, triplet energy transfer (ET) from the Au- to the Ti-containing chromophores, is provided. The cytotoxicity of the complexes was evaluated on A2780 ovarian cancer cells and on their cisplatin-resistant cell line A2780cisR; the compounds showed activity in the low micromolar range that was markedly more active than the corresponding titanocene-phosphine precursors [(η(5)-C(5)H(5))(η(5)-C(5)H(4)(CH(2))(n)PPh(2))TiCl(2)], cisplatin, and, for some of them, the gold analogue [(PPh(3))AuCl]. In an attempt to draw preliminary structure-activity relationships, cell uptake measurements and interaction studies with plasmid DNA and the model protein ubiquitin (Ub) have been undertaken on some of the compounds.