A novel synthesis of substituted 3-amino and 3-thio pyrimido[5,4-e]-1,2,4-triazine-5,7(1H,6H)-diones

Fervenulin is a natural product that has been extensively studied due to its molecular features and breadth of biological activities. Published studies have reported the generation of numerous analogues of the bicyclic pyrimidotriazinodione core. One underrepresented subclass are compounds with electron releasing atoms bonded directly to the C-3 position. We report an efficient and straightforward synthesis of compounds with substituted amino and thio functionality attached to the C-3 position. These are derived from a common 3-chloro precursor that is made in six steps in 15.8% overall yield from a starting chlorouracil. Our methodology should be applicable to the synthesis of C-3 ether congeners also, and through previously described chemistry be expandable to incorporating diversity at the N-6 position of the pyrimidotriazinodione core. The chemistry reported herein expands possibilities for the generation of diverse libraries of substituted pyrimidotriazinediones for future studies.     

System size, energy, pseudorapidity, and centrality dependence of elliptic flow

This Letter presents measurements of the elliptic flow of charged particles as a function of pseudorapidity and centrality from Cu-Cu collisions at 62.4 and 200 GeV using the PHOBOS detector at the Relativistic Heavy Ion Collider. The elliptic flow in Cu-Cu collisions is found to be significant even for the most central events. For comparison with the Au-Au results, it is found that the detailed way in which the collision geometry (eccentricity) is estimated is of critical importance when scaling out system-size effects. A new form of eccentricity, called the participant eccentricity, is introduced which yields a scaled elliptic flow in the Cu-Cu system that has the same relative magnitude and qualitative features as that in the Au-Au system.     

Solution processing of polymer semiconductor: Insulator blends—Tailored optical properties through liquid–liquid phase separation control

It has been demonstrated that the 0‐0 absorption transition of poly(3‐hexylthiophene) (P3HT) in blends with poly(ethylene oxide) (PEO) could be rationally tuned through the control of the liquid–liquid phase separation process during solution deposition. Pronounced J‐like aggregation behavior, characteristic for systems of a low exciton band width, was found for blends where the most pronounced liquid–liquid phase separation occurred in solution, leading to domains of P3HT and PEO of high phase purity. Since liquid–liquid phase separation could be readily manipulated either by the solution temperature, solute concentration, or deposition temperature, to name a few parameters, our findings promise the design from the out‐set of semiconductor:insulator architectures of pre‐defined properties by manipulation of the interaction parameter between the solutes as well as the respective solute:solvent system using classical polymer science principles. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2015 , 53, 304–310     

Ready access to 7,8‐dihydro‐ and 1,2,3,4‐tetrahydro‐1,6‐naphthyridine‐5(6H)‐ones from simple pyridine precursors

Short pathways are described for the synthesis of a representative example of each of the 7,8‐dihydro‐and 1,2,3,4‐tetrahydro‐1,6‐naphthyridine‐5(6H)‐one ring systems from simple pyridine precursors. An attempted synthesis of the related 4,6‐dihydro‐1,6‐naphthyridin‐5(1H)‐one ring system from a common intermediate was unsuccessful.     

Perforated organometallic nanotubes prepared from a Rh N-heterocyclic carbene using a porous alumina membrane

Fabrication of perforated organometallic nanotubes using a di-rhodium bis(N-heterocyclic carbene) complex by a simple nanoporous template wetting technique is described along with characterization data from scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy dispersive X-ray spectroscopy (EDS), proton NMR and Mass spectroscopy.     

Importance of correlations and fluctuations on the initial source eccentricity from Glauber simulations

Various ways of defining the initial source eccentricity in nucleus-nucleus collisions are discussed. In particular, we examine the participant eccentricity, which quantifies the eccentricity of the initial source shape by the major axes of the overlap ellipse formed by the interaction points of the participating nucleons. We find that participant spatial correlations in the interaction of two nuclei play an essential role, in particular for the Cu+Cu system. Including these correlations in the calculation of the participant eccentricity results in larger values for the eccentricity.     

Synthesis, manipulation and conductivity of supramolecular polymer nanowires

The synthesis of supramolecular conducting nanowires can be achieved by using DNA and pyrrole. Oxidation of pyrrole in DNA-containing solutions yields a material that contains both the cationic polypyrrole (PPy) and the anionic DNA polymers. Intimate interaction of the two polymer chains in the self-assembled nanowires is indicated by FTIR spectroscopy. AFM imaging shows individual nanowires to be continuous, approximately 5 nm high and conformationally flexible. This feature allows them to be aligned by molecular combing in a similar manner to bare DNA and provides a convenient method for fabricating a simple electrical device by stretching DNA/PPy strands across an electrode gap. Current-voltage measurements confirm that the nanowires are conducting, with values typical for a polypyrrole-based material. In contrast to polymerisation of pyrrole on a DNA template in bulk solution, attempts to form similar wires by polymerisation at surface-immobilised DNA do not give a continuous coverage; instead, a beads-on-a-string appearance is observed suggesting that immobilisation inhibits the assembly process.