An efficient ionic liquid mediated synthesis of substituted 5H[1,3]-thiazolo[2,3-b]quinazoline-3,5-(2H)-dione and 5H-thiazolo[2,3-b]quinazolin-5-one

A new, environmentally benign two-step synthesis of 5H[1,3]-thiazolo[2,3-b]quinazoline-3,5-(2H)-dione and 5H-thiazolo[2,3-b]quinazolin-5-one derivatives has been accomplished stepwise. The substituted 2-aminobenzoic acid upon condensation with thiourea in 1-butyl-3-methylimidazolium bromide at moderate temperature under nitrogen atmosphere yielded 2-thioxo-1H-4-quinazolinones. The resulting intermediate 2-thioxo-1H-4-quinazolinones, when reacted with 2-chloroethanoic acid/2-chloropropanal underwent cyclization to yield the desired product in excellent yields.     

Improved partition–expansion of two‐center distributions involving slater functions

The calculation of the electronic structure of large systems is facilitated by the substitution of the two‐center distributions by their projections on auxiliary basis sets of one‐center functions. An alternative is the partition–expansion method in which one first decides what part of the distribution is assigned to each center, and next expands each part in spherical harmonics times radial factors. The method is exact, requires neither auxiliary basis sets nor projections, and can be applied to Gaussian and Slater basis sets. Two improvements in the partition–expansion method for Slater functions are reported: general expressions valid for arbitrary quantum numbers are derived and the efficiency of the procedure is increased giving analytical solutions to integrals previously computed by numerical quadrature. The efficiency of the new version is assessed in several molecules and the advantages over the projection methods are pointed out. © 2013 Wiley Periodicals, Inc.     

Associative and segregative phase behaviour in mixtures of poly(N-tert-butylacrylamide) and poly(N,N-diethylacrylamide) with poly(4-vinylphenol): effect of solvent and concentration

Interpolymer complexation behaviour between poly(4-vinylphenol) (PVPh), as proton donor, and polyacrylamide derivatives, poly(N-tert-butylacrylamide) and poly(N,N-diethylacrylamide) (PNdEAm), as proton acceptor polymers, with both hydrogen bonding and hydrophobic properties, have been studied. Most mixtures studied in this work resulted in coprecipitation, that is, an associative phase separation. However, for the system PNdEAm/PVPh in aprotic solvents, tetrahydrofuran, acetone and 1,4-dioxane, either an associative (coprecipitation) or a segregative (precipitation of one polymer in presence of the other) behaviour is observed depending on concentration.     

Chemical Inhomogeneity,Short‐Range Order,and Magnetism in the LiNiO2‐NiO Solid Solution

NiO:Li is an early exemplar for which hole‐doping of a correlated insulator gives rise to rich and varied magnetic behavior. It is also an important system from the viewpoint of p‐type transparent conducting oxides, and is representative of a large class of materials that have been used in lithium ion batteries, since the end‐member compound, LiNiO₂, belongs to the class of layered cathode materials. Despite the deceptive structural and compositional simplicity of this system, a complete understanding of its complex magnetic properties has remained elusive. Here a comprehensive investigation of the solid solution Li_xNi_2?xO₂, examining samples of precise stoichiometry using a combination of high‐resolution synchrotron X‐ray powder diffraction and SQUID magnetometry, is provided. The focus is on the interesting region between 0.40<x<1.00 in which the magnetic ordering temperature changes drastically with composition. The magnetism evolves from strong G‐type antiferromagnetism of x=0.40 with T_N=327 K to robust uncompensated magnetic order at T_N=240 K when x is close to 0.7, and to glassy A‐type antiferromagnetism of x=1.00 at T_N=9 K. This study demonstrates this magnetic behavior is linked to the Li–Ni chemical order that develops from short‐ to long‐range. The interfaces between ordered domains give rise to magnetic exchange bias, which manifests as a shift in the magnetization‐field loop for samples with nanoscale coherence lengths (0.54<x<0.66).     

Study of Thin Polymeric Film Deposited by the PECVD Process for use at 193 nm

A plasma enhanced chemical vapor deposition (PECVD) reactor was used to deposit thin polymeric films with high absorption at 193 nm. The reactor is suitable to deposit uniform and pinhole free thin polymeric films with conformality over 95%. Conformal films with thickness as low as 200 Å have been deposited on silicon, glass, and quartz substrates, as well as silicon oxide, silicon nitrate, and aluminum films. Deposited films had variations in thickness of 3 to 5% over an area of 8 inches in diameter. Thin films deposited on silicon substrates under varying levels of RF power were scanned using the AFM technique. The measurements show increasing surface roughness of the scanned samples as the RF power increases.     

Synthesis,Structure, Magnetic Properties,and Catalase‐like Activity of Methoxy‐bridged Manganese(III) Coordination Polymer containing Hydrazone based (O,N,O)2‐Donor Ligand

A 1D coordination polymer of manganese(III) with a hydrazone‐based ligand, [Mn₂(L)(μ‐OCH₃)₂(OHCH₃)₂]_n ( 1 ), was synthesized and characterized by elemental analyses and spectroscopic methods {H₄L = bis[(2‐hydroxynaphthalen‐1‐yl)methylene]adipohydrazide}. The crystal structure of 1 was determined by X‐ray crystallography. The two dianionic domains of the ligand adopt trans configuration, and each coordinates in a tridentate mode via the O, N, O′‐donor atoms to a Mn^III ion forming a dinuclear compound. The methoxy ligands provide an asymmetric bridge between two central manganese atoms, which lead to the formation of a 1D coordination polymer. A 2D supramolecular structure is formed by hydrogen bonding interactions between the 1D chains. Although the methoxy ligands are labile, the polymer preserves its oligonuclearity in the solution. Temperature‐dependent magnetic susceptibility studies proved the presence of a weak antiferromagnetic interaction between manganese(III) ions with J = –3.2 cm^–1, which results from axial distortion of the manganese coordination environment. Compound 1 showed catalase‐like activity in disproportionation of H₂O₂.     

A note on sequences not having metric Poissonian pair correlations

Archiv der Mathematik - The purpose of this note is to present a construction of sequences which do not have metric Poissonian pair correlations (MPPC) and whose additive energies grow at rates...