The primary radical products, namely C60*? and C70*? which were formed by reactions with either the solvated electrons or (CH3)2*C(OH) radicals exhibit distinct absorption bands in the near-IR. Reaction of a water-soluble C60/γ-cyclodextrin complex with α-hydroxyalkyl radicals and hydrated electrons also involves electron transfer, as indicated by the dependence of the rate constants on the redox potential of the reducing species. Pulse radiolysis of micellar C60 solutions in BRIJ 35 and Triton X-100, on the other, exhibited electron transfer from various reducing radicals to the fullerence core. Water soluble fullerence mono-derivatives, e.g. C60[C(COO?2]2 (1) and C60(C9H11O2)(COO?) (2) did not show any noticeable reactivity towards strongly reducing species which can be ascribed to the formation of clusters in which the hydrophobic fullerence core is shielded by a surrounding layer of negatively charged carboxylate functions. Upon incorporation into γ-cyclodextrin the reduction of 1 and 2 occurs rapidly as indicated by both an accelerated decay of the hydrated electron absorption and the formation of the characteristic near-IR absorption due to (C60*?[C(COO?)/γ-CD and (C60*?) (C9H11O2)(COO?)/γ-CD at 1030 nm. The all-equatorial bis- and tris-adducts, e.g. equatorial-C60[C(COO?)2]2 and equatorial-C60[C(COO?)2]3, did not show any evidence with respect to the occurrence of aggregation phenomena and yielded the respective radical anions equatorial-(C60*?) [C(COO?)2]n in high yields. 相似文献
The [60]fulleride of bis(η-hexamethylbenzene)chromium(I) [(η6-C6Me6)2Cr]⋅+[C60]⋅−, and the complexes C60·C6Me6 and C60·C6Et6 were synthesized. Thermal decomposition of [(η6-C6Me6)2Cr]⋅+[C60]⋅− was studied. The molecular structures of C60·C6Me6 and C60·C6Et6 were determined.
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 2, pp. 220—224, February, 2006. 相似文献
CdS nanoparticles of 4.5 nm diameter were synthesized in poly(2‐vinylpyridine) micellar cores which were obtained by solvating a polystyrene‐block‐poly(2‐vinylpyridine) block copolymer in polystyrene‐selective toluene. Then, a C60‐toluene solution was dispersed into the CdS micelle solution with stirring. This led to the well‐defined organization of two different nanoparticles; specifically: a CdS NP decorated by several/dozens of C60 molecules, because C60 molecules were strongly coordinated with pyridine molecules in the micellar cores by charge‐transfer complexation C–P2VPδ+. A harmoniously organized CdS/C60 micellar structure was clearly verified by transmission electron microscopy. Fluorescent quenching of CdS nanoparticles, which was strongly affected by neighboring C60 molecules, was observed.
We have studied the molecular self-assembly tendency of C60(> DPAF-C9) dyad, C60(> DPAF-C9)2 triad, and C60(> DPAF-C9)4 pentads in a solvent-dependent and concentration-dependent manner. The evaluation was performed by the particle-size measurements on molecular assemblies in either toluene or CS2 using the dynamic light scattering technique. As a result, we observed a strong bimodal particle size distribution in most cases of the samples in both nonpolar solvents. In the instance of C60(> DPAF-C9) dyad, the first group of small nanoparticles exhibited a particle diameter size of 3.0–4.0 nm in good agreement with the estimated long axis length of C60(> DPAF-C9) (~ 2.7 nm), using 3D molecular modeling technique. Similar observation of a bimodal particle size distribution was detected on C60(> DPAF-C9)4 pentads in toluene with a small nanoparticle diameter size of ~ 8.0 nm fitting well with the estimated dimension length of ~ 9.8 nm for loosely packed 3–6 C60(> DPAF-C9)4 molecular assemblies. Furthermore, the tendency of forming large aggregation particles in a particle diameter of more than 4.0 μ m was significantly enhanced at a concentration of 1.0 × 10–2 M. 相似文献
A new kind of surfactant, [CnH_(2n+1)OCH2CH(OH)CH2N(CH3)3]Cl (n=12, 14, 16) was synthesized. The solubility of benzyl alcohol in micellar solutions was determined by 1H NMR method. The results indicate that the length of alkyl chains of surfactant affects the solubility of ben-zyl alcohol in 2.5 × l0~(-2) mol/L micellar solutions. The solubility of benzyl alcohol per liter of micellar solution is 0.095 mole for n=12, 0.115 mole for n=14, 0.165 mole for n=16. The transfer free energy of benzyl alcohol from aqueous phase to micellar phase is -24.29 kJ/mol for n=12, -24.37 kJ/mol for n=14, -24.49 kJ/mol for n=16. 相似文献
UV spectroscopy is used to determine the molar absorption coefficients of C60 fullerene and monosubstituted 1,2-dihydro-C60-fullerenes in different solvents. It is found that the extinction coefficient of C60 at 330 nm (the main absorption band most frequently used for qualitative and quantitative determination of the C60 content) is independent of the nature of the solvent and is ~54400 M?1·cm?1. The molar absorption coefficients of a series of monosubstituted 1,2-dihydro-C60-fullerenes are practically independent of the chemical structure and the length of the substituent and are 35700 M?1·cm?1 (λ ~ 328 nm) and 115250 M?1·cm?1 (λ ~ 257 nm). It is shown that the substitution in fullerene proceeds via the double 6,6 bond, as evidenced by the absorption band at 424 nm in the spectra of these compounds, which is characteristic of monosubstituted methanofullerenes. 相似文献
The diffusion-controlled adsorption kinetics of micellar surfactant C12E7 (heptaethylene glycol monododecyl ether) solutions was studied theoretically and experimentally. The corrected diffusion equation, which was used to describe the diffusion of the monomers in the micellar solutions, was solved under the initial and boundary conditions by means of Laplace transformation. The dynamic surface adsorption γ(t) as a function of surface lifetime t, monomer diffusion coefficient D and the demicellization constant was derived. The dynamic surface tensions γ(t) of aqueous submicellar and micellar solutions were measured via maximal bubble pressure method. By analyzing the experimental data, the determined demicellization constant of C12E7 at 25°C was between 100–116 s?1. 相似文献
New dimeric functionalized surfactants, 3,3′-[2-(hydroxyimino)propan-1,3-diyl]bis(1-alkyl-1H-imidazol-3-ium) dichlorides (Alk = C12H25, C14H29, C16H33), underlie the supernucleophilic microorganized systems capable of abnormally fast cleavage of acyl-containing substrates. Micellar effects both of monomeric and dimeric imidazolium surfactants in the cleavage processes of 4-nitrophenyl esters of diethylphosphonic, diethylphosphoric, and 4-toluenesulfonic acids are governed mostly by the hydrophobicity of the reaction components (acceleration ~102–103 times). The unquestionable advantage of dimeric surfactants is their especially low critical micelle concentrations (≤10?5 mol L?1), providing a possibility to attain the same micellar effects at the surfactant concentration lower by an order of magnitude (and yet even lower) than in the case of monomeric analogs. 相似文献
The characteristics of the radical sources in highly dispersed C60 samples supported on silica, titania ad alkali cation-exchanged Y-zeolite were investigated in the presence and absence of NO and O2by means of ESR, FT-IR and UV-diffuse reflectance spectroscopies, the results of which were compared with those of the bulk C60 sample. In the presence of O2, C60 dispersed onto supports was found to easily generate ESR signals in ambient conditions or under UV-irradiation. The intensity of the ESR signal of the C60 samples were found to strongly depend on the dispersibility of C60, the kind of support and the degassing temperature. Based on these results, the nature of these ESR active species in C60 was discussed in detail for the first time. The addition of NO led to a dramatic decrease in the intensity of the ESR signal, its extent also strongly depending on the kind of support, i.e., silica or Y-zeolite and the exchanged-alkali cations on zeolite, i.e., H+, Na+, Cs+, while such a decrease was not observed for the bulk C60. 相似文献
Two molecular Janus particles based on amphiphilic [60]fullerene (C60) derivatives were designed and synthesized by using the regioselective Bingel–Hirsh reaction and the click reaction. These particles contain carboxylic acid functional groups, a hydrophilic fullerene (AC60), and a hydrophobic C60 in different ratios and have distinct molecular architectures: 1:1 (AC60–C60) and 1:2 (AC60–2C60). These molecular Janus particles can self‐assemble in solution to form aggregates with various types of micellar morphology. Whereas vesicular morphology was observed for both AC60–C60 and AC60–2C60 in tetrahydrofuran, in a mixture of N,N‐dimethylformamide (DMF)/water, spherical micelles and cylindrical micelles were observed for AC60–C60 and AC60–2C60, respectively. A mechanism of formation was tentatively proposed based on the effects of molecular architecture and solvent polarity on self‐assembly. 相似文献
The rate constants for the addition of the OP·(OPri)2, Me3C·, and Me(CH2)3·CH2 radicals to the methano[60]fullerenes C60CX1X2 (X1 = X2 = CO2Et; X1 = CO2Me, X2 = OP(OMe)2; X1 = X2 = OP(OEt)2) were determined by ESR spectroscopy. Methanofullerenes are more reactive toward these radicals than C60 fullerene. 相似文献
New composite proton-conducting materials based on cesium hydrosulfate with fullerite C60 were synthesized. The concentration dependence of the proton conductivity and thermal properties of synthesized materials with C60 contents from 0 to 50 vol % was studied. It was found that these dependences are nonmonotonic with extrema at C60 contents of ~2 and 30 vol %. The conductivity of the composite material with a C60 content of ~2 vol % is almost twice higher than the conductivity of pure CsHSO4 due to the formation of a new surface phase, which is confirmed by thermal analysis methods. 相似文献
The limitations of macroscopic models of micellar solutions are revealed by thermodynamic and kinetic studies of micellar catalysis and in fact the properties of such media are essentially dependent on the microscopic organization. The micellar effects of CTAB [C16H33N+(CH3)3Br?] and SDS (C12H25SO4?Na+) on the competitive reactions (SN1, SN2 and E2) of 1-bromo-2-phenyl propane in basic medium and on the alkaline and neutral hydrolysis of α-phénylallylic esters has been studied. The specific effect of the micellar microenvironment is shown. The results are interpreted in terms of an enhancement of the nucleophilicity of the hydroxide ion and a diminution of the nucleophilic and electrophilic properties of water. The variation of the catalytic effect of cationic micelles with the concentration of the nucleophilic reagent is discussed. 相似文献
Abstract Interaction between dye (ECAB), nonionic surfactant (TX-100) micelle in aqueous solution and TX-100 hemimicelie at solid (SiO2)/liquid interface has been investigated quantitatively. There are linear relationships between concentrations of free ECAB(Ca), ECAB bound with TX-100 micelles in solution(Cm) and ECAB bound with TX-100 hemimicelles at interface of solid/liquid(Chm). The slopes of the three straight lines are 0.32 for Chm~Ca -1.32 for Cm~Ca and -1.00 for (Cm+Chm~Ca respectively. The linear relationships can be described by three linear equations as follows: Chm=0.32 (Ca?O.88×10?5),Cm.=4.0×10?5-l.33 Ca and Chm+Cm=3.742×l0?5-Ca,. It is inferred that the interaction between ECAB, TX-100 micelles and TX-100 hemimicelles is essentially partition of ECAB molecules in solution, TX-100 micelles and hemimicelles. The concentration of ECAB bound with TX-100 micelles well as electronic repulsion. Additionally, A quantitative method to determine adsorbance of surfactant TX-100 on silica gel by spectroscopy in coadsorption conditions of dye (ECAB) and TX-100 was proposed. 相似文献
ABSTRACT The influence of octaethylene glycol mono-n-hexadecyl ether (C16EO8) and sodium dodecyl sulphate (SDS) on the crystallization of calcium oxalate from 0.3 mol dm?3 sodium chloride solutions has been investigated. The critical micellar concentration (CMC) of C16EO8 in water and 0.3 mol dm?3 NaCl was determined by surface tension measurements (CMCH2O=CMCNaCl = 7.2.10?6 mol dm?3). The kinetics of precipitation of calcium oxalate was followed by Coulter counter, and solid phases were characterized by polarized microscopy, thermal analysis and X-ray powder diffraction patterns. Under the precipitation conditions employed, the thermodynamically stable monohydrate, CaC2O4?H2O (COM) was the predominant crystalline form. In the presence of micellar solutions of C16EO8 precipitation of this phase was facilitated as evidenced by higher initial precipitation rates and higher precipitate volume and number of particles, as compared to the controls. Micellar solutions of 50S retarded precipitation but induced crystallization of calcium oxalate dihydrate, CaC2O4?(2+×)H2O (COD, x≤0.5). Thus at c(SDS>CMC the precipitates contained ≥85 mass % COD. The results are discussed in relation to previously reported data on the precipitation of calcium oxalate in the presence of dodecyl ammonium chloride 相似文献
Porous sol-gel glasses with various pore size distributions are prepared and either impregnated with pure C60 or soaked with methanofullerenes or fullerodendrimers derivative solution. Induced absorption or reverse saturable absorption (RSA) has been studied in both types of solid materials. The samples impregnated by pure C60 mainly contain well-dispersed fullerene molecules. Unlike crystalline films of C60, their absorption dynamics can be well described by a 5-level model, developed for non-interacting C60-molecules in solutions. Methanofullerene samples, on the other hand, show signs of micellar aggregation and therefore RSA dynamics, which are influenced by solid state effects. Fullerodendrimers derivatives lead to the highest quantum yield. 相似文献
The electrowetting of a dielectric SiO2 film 100 nm thick by drops (D = 2–3 mm) of [C4mIm][PF6], [C6mIm][PF6], and [C6mIm][BTI] ionic liquids was studied at |U| ≤ 60 V in a ~10?8 mbar vacuum. Electrocapillary curves of the dependence of the wetting angle on electric field potential were constructed with an accuracy of ±1 deg. In conformity with the Young-Lippman equation, the wetting angle θ° decreased by the parabolic law from 51° to 43° for [C4mIm][PF6], from 48° to 38° for [C6mIm][PF6], and from 35° to 27° for [C6mIm][BTI] as |U| increased at 298 K. The electrocapillary curve branches were situated symmetrically in the (θ°, U) coordinates with respect to the line passing through the point U = 0; that is, zero-charge potential is zero for the electrowetting of the dielectric film by the ionic liquids. The capacitance of the double electrical layer at the ionic liquid-dielectric interface was determined. This value was found to be 4.65, 2.93, and 1.73 μF/m2 for the electrowetting of the SiO2 film at 298 K by the ionic liquids specified, respectively. 相似文献