Acid-Catalyzed Reactions of 2,3-Epoxy Derivatives of Citral with Alcohols

Acid-catalyzed reactions of 2,3-epoxy derivatives of citral (which is a widely spread naturally occurring unsaturated aldehyde) with alcohols were studied under conditions of heterogeneous catalysis and in fluorosulfonic acid. A number of new products were obtained, and possible mechanisms of their formation were proposed.     

Kinetics and mechanisms of the UV-radiation-assisted formation of gold nanoparticles in HAuCl<Subscript>4</Subscript>-doped chitosan solutions

Using methods of optical spectroscopy and small-angle X-ray scattering, the kinetics of the UV radiation-induced formation of gold nanoparticles in HAuCl₄-doped water–acid solutions of chitosan has been studied from the very beginning of the reaction. It has been shown that, during synthesis, as the mean size of nanoparticles grows from 2.9 to 6.3 nm, the maximum of the plasmon resonance shifts toward shorter waves (535–523 nm), whereas for a fully formed ensemble of nanoparticles, the reverse trend is observed. It has been found experimentally that the particle size distribution curve changes during synthesis. Based on the inverse problem analysis, conclusions have been drawn regarding the dominant mechanisms behind nanoparticle growth.     

Complexes of Zn(II) and Сu(II) with the Amino Derivatives of Deoxycholic Acid: Syntheses,Structures, and Properties

Russian Journal of Coordination Chemistry - Complexes [Zn(L)Cl2] (I), Cu(L)Cl2 ? H2O (II), Zn(L1)Cl2 ? 0.5H2O (III), and Cu(L1)Cl2 ? 0.5H2O (IV) (where L and L1 are the...     

Transformations of diepoxy derivatives of limonene in homogeneous acidic media

Transformations of diepoxy derivatives of limonene under conditions of homogeneous acid catalysis were studied, and their results were compared with those obtained over heterogeneous catalysts. A number of previously unknown compounds were isolated. The most possible transformation pathways were analyzed by computer simulation using molecular-mechanics and quantum-chemical methods.     

Tributylborane in the synthesis of graft copolymers of collagen and polymethyl methacrylate

Russian Chemical Bulletin - Graft copolymers of collagen and polymethyl methacrylate were synthesized in a suspension of an acetic acid dispersion of fish collagen and methyl methacrylate in the...     

Transformations of Isocaryophyllene Diepoxide under Conditions of Homogeneous and Heterogeneous Acid Catalysis

Transformations of isocaryophyllene diepoxide (an isomer of widely spread natural sesquiterpene) were studied in various acidic media under conditions of homogeneous and heterogeneous catalysis. A number of previously unknown compounds were thus obtained. The experimental data were compared with the results of molecular-mechanics and quantum-chemical simulation of the most probable transformation paths.     

New chiral ligands from myrtenal and caryophyllene for asymmetric oxydation of sulfides catalyzed by metal complexes

From myrtenal and caryophyllene, widespread terpene compounds, three new chiral Schiff bases were prepared suitable for ligands in vanadium ions catalyzed sulfides oxidation to chiral sulfoxides.     

High-contrast mapping of basal cell carcinomas

Because of low optical contrast in the visible spectral range, accurate detection of basal cell carcinomas (BCC) remains a challenging problem. In this letter, we experimentally demonstrate that reflectance confocal imaging in the vicinity of 1300 nm can be used for the detection of BCC without exogenous contrast agents. We present high-contrast reflectance confocal images of thick fresh skin tissues with clearly delineated cancer and discuss possible reasons for causing decreased scattering of BCC. Comparison with histopathology confirms that tumors scatter less and exhibit lower pixel values in the images, as compared to benign skin structures. The results demonstrate the feasibility of real-time noninvasive detection of BCC using intrinsic differences in scattering between tumors and normal skin.     

Photoinduced nanocomposites—creation, modification, linear and nonlinear optical properties

UV irradiation of materials consisting of a polymer matrix that possesses precursors of noble metals followed by annealing results in creation of metal nanoparticles within the irradiated domains. Such photoinduced nanocomposites are promising for photonics applications due to the strong alteration of their optical properties compared to initial nonirradiated materials. We report our results on the synthesis and investigation of two kinds of these materials:

1. Photoinduced Au nanocomposites based on PMMA matrices, including bulk materials prepared by means of the polymerization technique;
2. photoinduced Ag nanocomposites with an organic–inorganic hybrid matrix based on TiO₂ gels.

The experimental data on evolution of absorption spectra of these materials due to laser irradiation at different wavelengths are presented. The linear and nonlinear refractive index changes in these materials owing to light-induced nanonstructuring are investigated.