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131.
Synthesis and Rearrangement of P‐Nitroxyl‐Substituted PIII and PV Phosphanes: A Combined Experimental and Theoretical Case Study
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Tobias Heurich Dr. Zheng‐Wang Qu Dr. Senada Nožinović Dr. Gregor Schnakenburg Dr. Hideto Matsuoka Prof. Dr. Stefan Grimme Prof. Dr. Olav Schiemann Prof. Dr. Rainer Streubel 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(29):10102-10110
Low‐temperature generation of P‐nitroxyl phosphane 2 (Ph2POTEMP), which was obtained by the reaction of Ph2PH ( 1 ) with two equivalents of TEMPO, is presented. Upon warming, phosphane 2 decomposed to give P‐nitroxyl phosphane P‐oxide 3 (Ph2P(O)OTEMP) as one of the final products. This facile synthetic protocol also enabled access to P‐sulfide and P‐borane derivatives 7 and 13 , respectively, by using Ph2P(S)H ( 6 ) or Ph2P(BH3)H ( 11 ) and TEMPO. Phosphane sulfide 7 revealed a rearrangement to phosphane oxide 8 (Ph2P(O)STEMP) in CDCl3 at ambient temperature, whereas in THF, thermal decomposition of sulfide 7 yielded salt 10 ([TEMP‐H2][Ph2P(S)O]). As well as EPR and detailed NMR kinetic studies, indepth theoretical studies provided an insight into the reaction pathways and spin‐density distributions of the reactive intermediates. 相似文献
132.
Maja Trček George Cordoyiannis Brigita Rožič Vassilios Tzitzios George Nounesis Samo Kralj 《Liquid crystals》2017,44(10):1575-1581
We report on the stabilisation of the liquid-crystalline, twist-grain boundary A (TGBA) phase in mixtures of a chiral liquid crystal and surface-functionalised spherical Au nanoparticles (NPs) of 10 nm diameter. The results, obtained by calorimetric, optical, small-angle X-ray and plasmon resonance measurements, demonstrate that a TGBA phase, which is metastable for the pure liquid crystal host, can be effectively stabilised for a 3 K range in the presence of NPs. Moreover, the role of NPs size on the TGBA stabilisation is briefly discussed. 相似文献
133.
134.
Adamantyl ferrocene derivatives: Antioxidant abilities and effects on model lipid membranes
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Adela Štimac Jasmina Lapić Valentino Blasina Marija Lukinac Senka Djaković Ivo Crnolatac Leo Frkanec Ruža Frkanec 《应用有机金属化学》2018,32(2)
A series of homoannularly and heteroannularly substituted adamantyl ferrocene derivatives has been synthesized and their effects on membrane fluidity were investigated using liposomes as the membrane models. The liposome formulations of adamantyl ferrocene derivatives were characterized by using dynamic light scattering, differential scanning calorimetry and fluorescence anisotropy measurements. It was demonstrated that adamantyl ferrocene derivatives incorporated into the liposome significantly affect the structure of the lipid bilayer. The results of the study have revealed that adamantyl ferrocene derivatives, compounds 9 – 12, partition into the hydrophobic/hydrophilic interface of the membrane, causing a significant decrease in membrane fluidity. The antioxidant potential of synthesized compounds was assessed with DPPH method and it was shown that the examined compounds possess certain antioxidant activity. 相似文献
135.
Gordan Horvat Josip Požar Zvonimir Dojnović Dragutin Grgec Saša Blažeka 《Journal of Thermal Analysis and Calorimetry》2014,117(2):901-907
A quasi-adiabatic calorimeter for determining the molar solution enthalpies (Δsol H) of non-volatile solids was constructed. The design of the instrument was adjusted to allow the determination of solution enthalpies of small amounts of solids. For that purpose, the novel apparatus for sample dosage with virtually negligible “blank heat” was built. The rather low heat capacity of the calorimeter was achieved by reducing the volume of the reaction cell (20 mL), the dosing unit, and electric elements (the thermistor and the heater). Good thermal isolation of the reaction cell from the surroundings was accomplished by placing the cell into an evacuated polypropylene vessel. A computer program for processing the calorimetric data according to modified Regnault–Pfaundler method was written. The performance of the calorimeter was tested by determining the heats of the reactions serving as thermochemical standards at 25 °C (the dissolution of KCl and NaCl in water and the dissolution of tris(hydroxymethyl)-aminomethane in 0.1 mol dm?3 HCl(aq)). The obtained data were in very good agreement with the literature values. 相似文献
136.
The fast transient fluorescence (FTRF) technique was used to study critical exponents at the glass transition in free-radical crosslinking copolymerization (FCC) for two different monomeric systems, methyl methacrylate (MMA) and styrene (S). Pyrene (Py ) was used as a fluorescence probe. The fluorescence lifetimes of Py from its decay traces were measured and used to monitor the gelation process. Changes in the viscosity of the pregel solutions due to glass formation dramatically enhance the fluorescent yield of aromatic molecules. This effect is used to study the glass transition upon gelation of MMA and S monomeric systems as a function of time, at various temperatures and crosslinker concentrations. The results are interpreted in the view of percolation theory. The gel fraction and weight average degree of polymerization exponents β and γ are found to be 0.37 ± 0.02 and 1.66 ± 0.07 in agreement with percolation results. 相似文献
137.
Jelena Vasiljević Samira Hadžić Ivan Jerman Lidija Černe Brigita Tomšič Jožef Medved Matjaž Godec Boris Orel Barbara Simončič 《Polymer Degradation and Stability》2013
The aim of this study was to introduce a non-formaldehyde inorganic–organic hybrid sol–gel flame-retardant precursor (SiOP) containing phosphorous, nitrogen, and silicon and to compare its functional properties with those of the conventional formaldehyde-containing organic flame-retardant agent, organophosphonate (OP). SiOP was used at concentrations of 2%, 4%, and 8%, and OP was used at a concentration of 200 g/dm3. Both agents were applied to 100% cotton (CO) woven fabric by the pad-dry-cure method under the appropriate conditions. The presence of the SiOP and OP coatings on the CO fabric was confirmed by scanning electron microscopy, energy dispersive X-ray spectroscopy and Fourier-transform infrared spectroscopy. The results of the vertical tests of flammability and the thermogravimetric analyses showed that the presence of the SiOP coating changed the thermal degradation pathway of the CO fabric and resulted in an increase in the thermo-oxidative stability of the cellulose fibres. The thermo-oxidative stability was enhanced by the addition of higher amount of dry solids. At comparable dry solids contents, OP preserved significantly greater flame retardancy and thermo-oxidative stability than did SiOP. These results indicated that the SiOP precursor could not act as an effective alternative to the OP agent in the flame-retardant protection of CO fabric. 相似文献
138.
Lenka Blažková Lenka Malinová Václava Benešová Jan Roda Jiří Brožek 《Journal of polymer science. Part A, Polymer chemistry》2017,55(13):2203-2210
A successful preparation of polyamide 4 nanofibers via electrostatic spinning with diameters close to 100 nm is described. Polyamide 4 was prepared by the anionic ring‐opening polymerization of 2‐pyrrolidone and characterized. The effect of the system parameters (i.e., molar mass of the polymer, the solvent system) and the process parameters (i.e., the electrode‐to‐collector distance) during the electrostatic spinning have been studied. The morphology of the polyamide 4 fiber layers is given except molar mass of the polymer and the concentration of its solution primarily by the conformation of polyamide chains due to polyelectrolyte effect which was confirmed by viscosity measurements. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017 , 55, 2203–2210 相似文献
139.
The packing chromatic number
$$\chi _{\rho }(G)$$ 相似文献
140.