From 1,2,4-triazines towards substituted pyridines and their cyclometallated Pt complexes

A new, efficient methodology for the synthesis of substituted thienylpyridines includes the synthesis of 3-thienyl-1,2,4-triazines using simple heterocyclisation followed by easy transformation of the triazine ring to a pyridine through an aza Diels-Alder approach. A variety of substituted pyridines can be easily achieved using cheap, commercially available reagents such as bromoacetylarenes, aroyl hydrazides, norbornadiene, and enamines in various combinations. New thienylpyridines form phosphorescent cyclometallated Pt complexes.     

9-Allyl-1,7-dicarbadodecaborane as a dienophile in aza Diels-Alder reactions of 1,2,4-triazines: synthesis of pyridines bearing a carborane cage

The synthesis of pyridine and bipyridine derivatives of m-carborane via aza Diels-Alder reaction of 1,2,4-triazines with 9-allyl m-carborane and their structural characterization and photophysical properties are described. The products 3- and 4-(m-carborane-9-ylmethyl)-2,2′-bipyridines form Zn(II) complexes on reaction with ZnCl₂, which increases significantly their fluorescence intensity.     

Scheduling UET-tasks on a star network: complexity and approximation

In this article we investigate complexity and approximation on a processor network where the communication delay depends on the distance between the processors performing tasks. We then prove that there is no polynomial-time heuristic with a performance guarantee smaller than ${\frac{6}{5}}$ (respectively ${\frac{14}{13}}$ ) for minimization of the makespan (respectively the total job completion time) on a processor network represented by a star. Moreover, we design an efficient polynomial-time approximation algorithm with a worst-case ratio of four. We also prove that a polynomial-time algorithm exists for a schedule with a length of at most four. Lastly, we generalize all previous results on complexity and approximation.     

Ditopic complexes of silene H2SiCH2 with bidentate ligands Me2NCH2SiHnF3-n. Structures, formation energies, AIM and ELF analyses.

Ditopic complex formation of silene H₂SiCH₂ with bidentate ligands Me₂NCH₂SiH_nF_3-n (n = 0-3) was studied at the MP4(SDQ(T)6-311G(d,p))//MP2/6-31G(d,p) levels of theory. The AIM and ELF analyses have shown that π-bonding in the silenic Si¹C moiety in the relatively weak (H₂Si¹CH₂)·(Me₂NCH₂Si²H_nF_3-n) (n = 2, 3) ditopic complexes is partially preserved.     

General quasi-nonspreading linear three-dimensional wave packets

We introduce a general approach for generation of sets of three-dimensional quasi-nonspreading wave packets propagating in linear media, also referred to as linear light bullets. The spectrum of rigorously nonspreading wave packets in media with anomalous group velocity dispersion is localized on the surface of a sphere, thus drastically restricting the possible wave packet shapes. However, broadening slightly the spectrum affords the generation of a large variety of quasi-nonspreading distributions featuring complex topologies and shapes in space and time that are of interest in different areas, such as biophysics or nanosurgery. Here we discuss the method and show several illustrative examples of its potential.     

Production of new heavy isotopes in low-energy multinucleon transfer reactions

It is shown that the multinucleon transfer reactions in low-energy collisions of heavy ions may be used for production of new neutron-rich nuclei at the "northeast" part of the nuclear map along the neutron closed shell N=126 which plays an important role in the r process of nucleosynthesis. More than 50 unknown nuclei might be produced in such reactions (in particular, in collision of 136Xe with 208Pb) with cross sections of not less than 1 microb.     

Sublimation inside an elastoplastic material

Thermodynamic and kinetic approaches for sublimation inside elastoplastic material under tensile stress are developed for large strains. Various conceptual problems related to irreversible plastic deformation are addressed for a spherical bubble. They include definitions of the thermodynamic driving forces and activation energies, nontraditional concepts of a critical nucleus, path dependence of its appearance, modes of its growth (sublimation or expansion due to loss of mechanical stability), and the possibility of reverse transformation. The kinetic relationships between sublimation pressure and temperature are obtained.