Abstract Reaction of the 2-azidoalcohol 1 with 2-phenyl1-1,3,2-dioxaphospholane leads to a 4:1 mixture of the pentacoordinate phosphorane 3 and the diazadiphosphetidine 4. In solution, these compounds are in equilibrium, presumably involving the not detectable iminophosphorane 2. A single X-ray analysis carried out on 3 proves the structure of this type of compound which has been postulated earlier as intermediate in the synthesis of aziridines from azidoalcohols1,2相似文献
Abstract The stereochemical courses of phosphoryl transfer reactions in aprotic solvents and thiophosphoryl transfer reactions in protic solvent have been determined. The extensive racemisation observed in both instances is discussed in terms of metaphosphate and thiometaphosphate intermediates of significant life-times. 相似文献
Polymerizable rare earth complex Eu(AA)3Phen was synthesized by complexion of europium ion, acrylic acid (AA), and 1,10-phenanthroline (Phen). The structure and fluorescence properties of the complex were studied by elemental analysis, 1H-NMR spectroscopy, and fluorescence spectroscopy. Eu-containing copolymer poly(PEGMA-co-MMA-co-METAC-co-Eu(AA)3Phen) (PPMMEu) was then synthesized by free radical copolymerization of Eu(AA)3Phen and other functional monomers including poly(ethylene glycol) methyl ether methacrylate (PEGMA) and [2-(Methacryloyloxy) ethyl] trimethylammonium chloride (METAC). 1H-NMR spectroscopy and fluorescence spectroscopy were used to characterize the copolymer and the interactions between the copolymer and DNA was investigated by TEM, fluorescence spectroscopy, and agarose gel electrophoresis. The desired luminescent cationic copolymer was successfully obtained. The copolymer can form micelles in water solution and can efficiently bind to DNA molecules through electrostatic interaction. The results suggest the potential use of PPMMEu in bioprobes and gene vectors. 相似文献
The completely conjugated polymer, polyethynylferrocene, was prepared by heating ethynylferrocene with catalytic amounts of azobisisobutyronitrile to 180-240[ddot] under nitrogen in bulk. Cyclotrimerization competes with polymerization under these conditions. Pure low molecular weight polyethynylferrocene was isolated and characterized by IR and NMR spectroscopy and by a gel permeation chromatography. The pure polymer exhibits a conductivity of 2 × 10?14?1 cm?1. Attempts to prepare polyethynylferrocene by heating acetylferrocene in molten zinc chloride were, contrary to literature reports, unsuccessful. A polymer containing hydroxyl and keto groups was obtained, and extensive degradation of the ferrocene groups occurred. The general reaction scheme is discussed. It includes cleavage of cyclopentadienyl rings from ferrocene and the incorporation of cyclopentane rings into the polymer structure. 相似文献
This paper presents a study regarding the obtaining of NiCr2O4 by two new unconventional synthesis methods: (i) the first method is based on the formation of Cr(III) and Ni(II) carboxylate-type precursors in the redox reaction between the nitrate ion and 1,3-propanediol. The thermal decomposition of these complex combinations, at ~300 °C, leads to an oxide mixture of Cr2O3+x and NiO, with advanced homogeneity, small particles and high reactivity. On heating this mixture at 500 °C, Cr2O3 reacts with NiO to form NiCr2O4, which was evidenced by FT-IR and X-ray diffractometry (XRD) analysis; (ii) the second method starts from a mechanical mixture of (NH4)2Cr2O7 and Ni(NO3)2·6H2O. On heating this mixture, a violent decomposition at 240 °C with formation of an oxides mixture (Cr2O3 + CrO3) and NiO takes place. On thermal treatment up to 500 °C, an intermediary phase NiCrO4 is formed, which by decomposition at ~700 °C leads to NiCr2O4, evidenced by FT-IR and XRD analysis. NiCr2O4 is formed, in both cases, starting with a temperature higher than 400 °C, when the non-stoichiometric chromium oxide (Cr2O3+x) loses the oxygen excess and turns to stoichiometric chromium oxide (Cr2O3), which further reacts with NiO. 相似文献
The study reports the preparation of CoFe2O4/SiO2 nanocomposites by a new modified sol–gel method starting from cobalt nitrate, iron nitrate, and diols: 1,2-ethanediol (EG), 1,3-propanediol (1,3PG), and tetraethylorthosilicate (TEOS), for final compositions of 30 %CoFe2O4/70 %SiO2 and 50 %CoFe2O4/50 %SiO2. The method is based on the formation of a Co(II), Fe(III)—carboxylate precursors mixture, during the redox reaction between the NO3? ion and the diol (~140 °C) within the silica gels. The thermal decomposition of these complex combinations takes place at ~300 °C leading to the corresponding amorphous metal oxides within the pores of the hybrid gels. Depending on the subsequent thermal treatment, CoFe2O4 can be obtained as single phase or in a mixture with Co2SiO4. The CoFe2O4 crystallites sizes are in the nanometer range (3–10 nm). The obtained nanocomposites have a hard magnet behavior, as a result of the high anisotropy of CoFe2O4 having large hysteresis cycles. 相似文献
A series of nanoparticles is prepared via layer‐by‐layer assembly of oppositely charged, synthetic biocompatible polyamidoamine polymers as potential carriers. Particle size, surface charge and internal chain mobility are quantified as a function of the polymer type and number of layers. The effect of addition of surfactant is examined to simulate the effects of nanoparticle dissolution. The cyctotoxicity of these particles (in epithelia and murine cell lines) are orders of magnitude lower than polyethyleneimine controls. Stable nanoparticles may be prepared from mixtures of strongly, oppositely charged polymers, but less successfully from weakly charged polymers, and, given their acceptable toxicity characteristics, such modularly designed constructs show promise for drug and gene delivery.