Sensing and fixation of NO2/N2O4 by calix[4]arenes

An approach toward visual detection and chemical utilization of NO(2)/N(2)O(4) is proposed, which employs simple calix[4]arenes. Exposure of tetra-O-alkylated calix[4]arenes 1 and 2, possessing either a cone or a 1,3-alternate conformation, to NO(2)/N(2)O(4), both in chloroform solution and in the solid state, results in deeply colored calixarene-nitrosonium (NO(+)) complexes. In the presence of a Lewis acid, such as SnCl(4), stable calixarene-NO(+) complexes 7 and 8 were isolated in a quantitative yield and characterized by UV-vis, FTIR, high-resolution (1)H NMR spectroscopy and elemental analysis. NO(+) is found encapsulated within the calixarene cavity, and stable charge-transfer complexes result with K(ass) > 10(6) M(-1) (CDCl(3)). The NO(+) encapsulation was also demonstrated in titration experiments with calixarenes 1, 2, and 5 and commercially available NO(+)SbF(6)(-) salt in chloroform. The complexation process is reversible, and the complexes dissociate upon addition of water and alcohol, recovering the parent calixarenes. Attachment of functionalized calix[4]arenes to silica gel was demonstrated, which afforded a solid material 15 capable of visual detection and entrapment of NO(2)/N(2)O(4). Calixarene-NO(+) complexes can be utilized for the NO(+) transfer processes and nitrosation reactions. The NO(+) guest transfer between two calixarene containers 2 and 5 was achieved and studied by UV-vis and (1)H NMR spectroscopy. Chemical fixation of NO(2)/N(2)O(4) was demonstrated through their quantitative transformation into the calixarene-NO(+) complex and its use as a nitrosonium transfer agent in the synthesis of N-nitrosoamides. These results may lead toward novel nitrogen oxides storing materials.     

2-Azaanthracene (microreview)

Chemistry of Heterocyclic Compounds - Microreview focuses on the main modern synthetic approaches toward 2-azaanthracene and its derivatives. These approaches are: inverse electron-demand...     

Parallelization of the algorithm of asymptotic partial domain decomposition in thin tube structures

The method of asymptotic partial domain decomposition for thin tube structures (finite unions of thin cylinders) is revisited. Its application to the Newtonian and non-Newtonian flows in great systems of vessels is considered. The possibility of a parallelization of its algorithm is discussed for linear and non-linear models.     

Shear and squeeze rheometry of suspensions of magnetic polymerized chains

We present the first experimental results on the magnetorheology of suspensions of non-Brownian magnetic ellipsoidal particles. These particles are made of spherical iron particles linked by polymers and are called polymerized chains. Steady shear, oscillatory shear, and oscillatory squeeze rheological tests have been performed. The rheological properties of the suspension of polymerized chains have been compared with those of the suspension of spherical iron particles. In shear flow, both suspensions develop nearly the same yield stress, while in squeeze flow, the yield stress is several times higher for the suspension of polymerized chains. We show that the squeezing force of a suspension of spherical particles is an increasing function of the magnetic field intensity at low magnetic fields but decreases dramatically at higher fields. Surprisingly, this phenomenon, attributed to cavitation or air entrainment, does not occur in the suspension of polymerized chains.     

Synthesis of hydrophobic derivatives of the G/\C base for rosette nanotube self-assembly in apolar media

Eleven self-complementary G/\C derivatives bearing hydrophobic moieties were synthesized and characterized. One representative derivative from this family was shown to self-assemble into rosette nanotubes in hexane and form Langmuir-Blodgett films at the air-water interface.     

A TQFT of Turaev–Viro Type on Shaped Triangulations

A shaped triangulation is a finite triangulation of an oriented pseudo-three-manifold where each tetrahedron carries dihedral angles of an ideal hyperbolic tetrahedron. To each shaped triangulation, we associate a quantum partition function in the form of an absolutely convergent state integral which is invariant under shaped 3–2 Pachner moves and invariant with respect to shape gauge transformations generated by total dihedral angles around internal edges through the Neumann–Zagier Poisson bracket. Similarly to Turaev–Viro theory, the state variables live on edges of the triangulation but take their values on the whole real axis. The tetrahedral weight functions are composed of three hyperbolic gamma functions in a way that they enjoy a manifest tetrahedral symmetry. We conjecture that for shaped triangulations of closed three-manifolds, our partition function is twice the absolute value squared of the partition function of Techmüller TQFT defined by Andersen and Kashaev. This is similar to the known relationship between the Turaev–Viro and the Witten–Reshetikhin–Turaev invariants of three-manifolds. We also discuss interpretations of our construction in terms of three-dimensional supersymmetric field theories related to triangulated three-dimensional manifolds.     

Diazocarbonyl and Related Compounds in the Synthesis of Azoles

Diazocarbonyl compounds have found numerous applications in many areas of chemistry. Among the most developed fields of diazo chemistry is the preparation of azoles from diazo compounds. This approach represents a useful alternative to more conventional methods of the synthesis of azoles. A comprehensive review on the preparation of various azoles (oxazoles, thiazoles, imidazoles, pyrazoles, triazoles, and tetrazoles) from diazocarbonyl and related compounds is presented for the first time along with discussion of advantages and disadvantages of «diazo» approaches to azoles.     

One-pot green synthesis and cytotoxicity of new <Emphasis Type="Italic">α</Emphasis>-aminophosphonates

A novel series of α-aminophosphonates containing the trifluoromethyl aniline moiety were obtained in high yields by condensation of 2-methyl-3-trifluoromethyl aniline, aryl/heteroaryl aldehydes and dimethylphosphite in the presence of chitosan as a catalyst. The molecular modeling studies revealed their important structural features of binding affinities towards the target enzyme. The cytotoxicity of these compounds was evaluated against PC-3(prostate cancer), MCF-7 (breast cancer), HeLa(cCervix Cancer), U973, K562 and HL60 human lLeukemia cell lines. Compound 4k with a pyrene moiety showed high potency against a breast cancer cell line, while compounds 4g and 4k exhibited more promising cytotoxicity against U973, K562 and HL60 cell lines.     

Wave Equation on One-Dimensional Fractals with Spectral Decimation and the Complex Dynamics of Polynomials

We study the wave equation on one-dimensional self-similar fractal structures that can be analyzed by the spectral decimation method. We develop efficient numerical approximation techniques and also provide uniform estimates obtained by analytical methods.