Critical role of water and the structure of inverse micelles in the Brust-Schiffrin synthesis of metal nanoparticles

Although Brust-Schiffrin two-phase synthesis is a popular method for synthesizing ligand-protected metal nanoparticles with an average size of less than 5 nm, the details on how the reactions can be controlled from a mechanistic point of view are still unclear, therefore hindering efforts to synthesize monodisperse metal nanoparticles. It was recently discovered that this method is basically an inverse-micelle-based synthesis (Li, Y.; Zaluzhna, O.; Xu, B.; Gao, Y.; Modest, J. M.; Tong, Y. Y. J. J. Am. Chem. Soc.2011, 133, 2092). In this letter, the critical role of water and the structure of inverse micelles in typical synthesis of gold nanoparticles were further investigated. We found that (1) water encapsulated in the inverse micelles of [TOA](+) that also hosted metal ions formed a hydrophilic microenvironment that acted as a reaction-enabling proton-accepting medium for the thiol protons (RS-H) and (2) not only the presence but also the amount of water in the reaction medium has a profound effect on the Au(I) precursor species (a pure [TOA][AuX(2)] complex or a mixture of a [TOA][AuX(2)] complex and polymeric [Au(I)SR](n) species), the reduction of Au(III) by thiols, and the formation of uniform small metal nanoparticles. A quantitative analysis of the (1)H NMR of the encapsulated water enabled an estimation of the size and composition of the involved inverse micelles.     

Self-organizing surface-initiated polymerization: facile access to complex functional systems

Facile access to complex systems is crucial to generate the functional materials of the future. Herein, we report self-organizing surface-initiated polymerization (SOSIP) as a user-friendly method to create ordered as well as oriented functional systems on transparent oxide surfaces. In SOSIP, self-organization of monomers and ring-opening disulfide exchange polymerization are combined to ensure the controlled growth of the polymer from the surface. This approach provides rapid access to thick films with smooth, reactivatable surfaces and long-range order with few defects and high precision, including panchromatic photosystems with oriented four-component redox gradients. The activity of SOSIP architectures is clearly better than that of disordered controls.     

Effect of amino acids on corrosion of copper and steel in acid medium

Efficiency of four amino acids (glycine, threonine, phenylalanine, and glutamic acid) in inhibition of corrosion of M3 copper and St.3 low-carbon steel in a 0.5 M HCl solution was evaluated.     

Comprehensive core-level study of the effects of isomerism, halogenation, and methylation on the tautomeric equilibrium of cytosine

Core-level X-ray photoemission and near-edge X-ray absorption fine structure spectra of 5-methylcytosine, 5-fluorocytosine, and isocytosine are presented and discussed with the aid of high-level ab initio calculations. The effects of the methylation, halogenation, and isomerization on the relative stabilities of cytosine tautomers are clearly identified spectroscopically. The hydroxy-oxo tautomeric forms of these molecules have been identified, and their quantitative populations at the experimental temperature are calculated and compared with the experimental results and with previous calculations. The calculated values of Gibbs free energy and Boltzmann population ratios are in good agreement with the experimental results characterizing tautomer equilibrium.     

Investigation of the mechanism of the recyclization of furans to thiophenes and selenophenes under acid-catalysis conditions. 3. Investigation of the recyclization of homologs and functional derivatives of furan. Quantum-chemical calculations of the objects of the recyclization

The kinetics of the conversion of di-, tri-, and tetraalkylfurans to the corresponding thiophenes were investigated. A correlation between the reactivities and structures of the investigated furans was established. Quantum-chemical calculations of the objects of the recyclization were made. The calculated and experimental data on the reactivities of the investigated compounds were compared. The most likely pathway of the protonation of furans in their recyclization was determined on the basis of calculations of the total energies of the protonated forms.For Communication 2 see [1].Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 12, pp. 1614–1620, December, 1993.     

Galois subrings of simple rings

Suppose R is a finite direct sum of simple associative rings and G is a finite group of auto-morphisms of the ring R. It is shown that if there is no additive ¦G¦-torsion in R, then the subring of elements of R that are fixed under G is a finite direct sum of simple rings.