Synthesis,characterization, and molecular recognition of sugar‐functionalized nanoparticles prepared by a combination of ROP,ATRP, and click chemistry

The aim of this work was to prepare nanoparticles bearing sugar residues at their surface through the synthesis of amphiphilic block copolymer of poly d,l‐lactide (PLA) and poly(ethylene glycol)methacrylate, with the hydrophilic part terminating with glucopyranoside molecules as a model for any carbohydrate ligand. The construction was achieved by a combination of click chemistry, ring‐opening polymerization, and atom transfer radical polymerization. The modified monomer and resulting copolymer were characterized by NMR, SEC, and FTIR. Nanoparticles with a mean hydrodynamic diameter of <200 nm as determined by quasi‐elastic light scattering were prepared from the amphiphilic copolymer by nanoprecipitation using dimethylformamide (DMF) as water‐miscible solvent. In the range of 2.5–10 mg copolymer/mL DMF, the polymer concentration did not have much effect on the size of the nanoparticles. Accessibility of glucopyranoside molecules on the surface of the nanoparticles was confirmed by formation of aggregates from nanoparticles in the presence of concanavalin A observed by transmission electronic microscopy. Finally, no significant cytotoxicity toward human umbilical vein endothelial cells was detected for the final nanoparticles. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 3178–3187, 2010     

Synthesis of 9-(hexane-1,6-diol-3-yl)purines,a novel series of acyclic nucleoside analogs and antiviral evaluation

New acyclic purine nucleoside analogs lacking the C(3′)? C(4′) bond, have been prepared from 4-aminocyclohexene and evaluated for antiviral activity. A new synthesis of 4-aminocyclohexene from cyclohex-3-ene-1-carbonyl chloride is also reported via a Curtius reaction. None of the two compounds exhibited any antiviral activity in vitro against HSV-1, HCMV and HIV-1.     

Etude en Spectrométrie de Masse. X—Fragmentation d'Ethanes Disubstitués par un Hétéroatome des Colonnes IV,V et VI,et par un Groupement Fonctionnel

In this paper, the behaviour of ethers, sulfides, selenoethers, amines, germanes and stannanes, substituted on the β-C by a methoxycarbonyl, methyl ketone, or cyano group is compared and discussed. The compounds containing group V_B or VI_B element are quite stable, while those with a group IV_B element fragment very easily. Fragmentation α to the heteroatom gives peaks for which the intensity increases with the size of the element:[PhO]⁺<[PhS]⁺<[PhSe]⁺<[Ph₃Ge]⁺<[Ph₃Sn]⁺. Fragmentation at the β position gives very important peaks when the ionization potential is low or when the substituents inductive effect is strong (CN<CO₂CH₃<COCH₃).     

Synthesis of s-triazolo[4,3-b]pyridazine C-nucleosides

A one step synthesis of s-triazolo[4,3-b]pyridazine using 3-chloro-6-hydrazinopyridazine and an appropriate thioformimidate is described. Applying this procedure to 5-O-benzoyl-1-benzylthio-1-formimidate-D-ribofuranose, 5′ benzoyl-6-chloro-3β-D-ribofuranosyl-s-triazolo[4,3-b]pyridazine was obtained. Substitutions of chlorine by nucleophilic reagents afforded some derivatives of a new series of C-nucleo-sides. Structural determination including anomeric configuration assignment is discussed based mainly on ¹H nmr spectroscopy.     

Initial members of the family of molecular mid-valent high-nuclearity iron nitrides: [Fe4N2X10]4- and [Fe10N8X12]5- (X = Cl-, Br-)

Current theoretical and experimental evidence points toward X = N as the identity of the interstitial atom in the [MoFe7S9X] core of the iron-molybdenum cofactor cluster of nitrogenase. This atom functions with mu6 bridging multiplicity to six iron atoms and, if it is nitrogen as nitride, raises a question as to the existence of a family of molecular iron nitrides of higher nuclearity than known dinuclear Fe(III,IV) species with linear [Fe-N-Fe]5+,4+ bridges. This matter has been initially examined by variation of reactant stoichiometry in the self-assembly systems [FeX4]1-/(Me3Sn)3N (X = Cl-, Br-) in acetonitrile. A 2:1 mol ratio affords [Fe4N2Cl10]4- (1), isolated as the Et4N+ salt (72%). This cluster has idealized C2h symmetry with a planar antiferromagnetically coupled [Fe(III)4(mu3-N)2]6+ core containing an Fe2N2 rhombus to which are attached two FeCl3 units. DFT calculations have been performed to determine the dominant magnetic exchange pathway. An 11:8 mol ratio leads to [Fe10N8Cl12]5- (3) as the Et4N+ salt (37%). The cluster possesses idealized D2h symmetry and is built of 15 edge- and vertex-shared rhomboids involving two mu3-N and six mu4-N bridging atoms, and incorporates two of the core units of 1. Four FeN2Cl2 and four FeN3Cl sites are tetrahedral and two FeN5 sites are trigonal pyramidal. The cluster is mixed-valence (9Fe(III) + Fe(IV)); a discrete Fe(IV) site was not detected by crystallography or M?ssbauer spectroscopy. The corresponding clusters [Fe4N2Br10]4- and [Fe10N8Br12]5- are isostructural with 1 and 3, respectively. Future research is directed toward defining the scope of the family of molecular iron nitrides.     

Relaxation phenomena of hydrolyzed polyvinylamine molecules adsorbed at the silica/water interface III. Interfacial exchange and transfer processes

Surface area exclusion chromatography (SAEC) was employed to determine the stability characteristics of saturated homogeneous layers when interfacial exchange or transfer of molecules was promoted. In these experiments, the first polymer layer was established by elution of a column composed of stacked glass-fiber filters with one polymer. Then, after displacement of the void by water, the second polymer was subsequently injected under the same elution conditions. The experiments combine polymers of equal or different molecular weight and/or hydrolysis grade. Histograms of SAEC experiments demonstrate the great stability of the initially adsorbed layer. Domains of high and low adsorption values were determined to exist along the chromatography column after injection of the first polymer sample. The polymer injected second slightly modifies the initial adsorption histogram and mainly overadsorbs on the low adsorption domain of the first polymer. The major result relates to the relaxation phenomenon affecting or not the second adsorbed polymer when it adsorbs on filters belonging to the low adsorption domain of the polymer first injected. The relaxation is impeded when the relaxation of the first polymer is of great amplitude, whereas it occurs when the relaxation of the first polymer is small.     

Etude en Spectrométrie de Masse. IX—Fragmentation de Cyclopropanes Dicarboxylate de Méthyle-1,2 cis et trans Diversement Substitués,et des Homologues Cyclobutaniques,Cyclopentaniques et Cyclohexaniques non Substitués

A mass spectral study of cis- and trans-decarboxymethylcyclopropanes substituted on C-1, C-2, C-3 reveals that they show the same behaviour under electron impact. In every case, breaking of the carbocyclic ring is the first step giving the most important peaks. By comparing unsubstituted diesters of cyclopropane with those of the cyclobutane, cyclopentane and cyclohexane homologues, we have analysed the transmission of electronic effects by the different rings.