Synthesis of unsymmetrical 4,6-diarylpyrimidines

Unsymmetrical 4,6-diarylpyrimidines were synthesized using Suzuki coupling reaction via selective arylation of 4,6-dichloropyrimidine.     

Vibrational spectra of ammonia chemisorbed on platinum (111): II. The electron scattering mechanism

We have measured the angle and energy dependence of the inelastic cross sections for NH₃ chemisorbed on Pt(111). The relative contributions of dipole and nondipole processes in the on-specular intensities were determined. The angular dependence (off-specular scattering) was found to be more useful than the impact energy dependence for discrimination between the two scattering mechanisms. For both molecular states of NH₃/Pt(111), strong impact scattering contributions were found in the NH stretching mode intensities. One particular mode, the degenerate stretch [ν_d(NH)] was selectively excited by impact scattering. The energy dependence showed an enhancement of all of the inelastic intensities at low impact energies (1 eV). This enhancement was found to be a result of a surface reflectivity increase, coupled with an increase in the inelastic cross section. The latter increase is not predicted by dipole theory. Determination of the molecular orientation was not possible, due to the complex contributions of dipole and impact scattering.     

The synthesis of XTT: A new tetrazolium reagent that is bioreducible to a water-soluble formazan

A new tetrazolium salt, XTT, has been synthesized. XTT is reduced by a considerable variety of cell lines to a water-soluble formazan. XTT appears to merit further investigation as a reagent for broader application to cell culture assay systems.     

Aqueous suspension polymerization of isobutene initiated by 1,2-C6F4[B(C6F5)2]2

Lewis acidic, chelating diborane 1 forms stable oxonium acids 2 in the presence of excess MeOH or water. Diborane 1 is shown to be an effective co-initiator for the suspension polymerization of isobutene in aqueous media at sufficiently low temperatures. Poly(isobutene) or butyl rubber is obtained at moderate to high conversion and with Mw < 200 K and PDI approximately 2 under these conditions.     

Effect of residual monomer on the spectroscopic properties of polythiophenes

The addition of some small molecules can red shift UV-Visible absorption and quench the fluorescence of poly(3-octadecylthiophene).     

Reconfiguration graphs of shortest paths

For a graph $G$ and$a,b\in V\left(G\right)$, the shortest path reconfiguration graph of $G$ with respect to $a$ and$b$ is denoted by $S(G,a,b)$. The vertex set of $S(G,a,b)$ is the set of all shortest paths between $a$ and$b$ in $G$. Two vertices in $V\left(S(G,a,b)\right)$ are adjacent, if their corresponding paths in $G$ differ by exactly one vertex. This paper examines the properties of shortest path graphs. Results include establishing classes of graphs that appear as shortest path graphs, decompositions and sums involving shortest path graphs, and the complete classification of shortest path graphs with girth 5 or greater. We include an infinite family of well structured examples, showing that the shortest path graph of a grid graph is an induced subgraph of a lattice.     

Modification of solid electrolyte interphase on deposited lithium metal by large separation between the electrodes in ether-based electrolytes

Journal of Solid State Electrochemistry - A thorough understanding of the lithium deposition behavior will facilitate the commercialization of lithium metal anodes. Despite enormous effort, an...