4-(4-Chlorophenyl)-3,7,7-trimethyl-1-[2-(4-nitrobenzoyl)ethyl]-4,7,8,9-tetrahydro-1H-pyrazolo[3,4-b]quinolin-5(6H)-one–ethanol (1/1)

Molecules of the title compound, C₂₈H₂₇ClN₄O₄·C₂H₆O, form a C(6) chain via an N—H⋯O hydrogen bond along the c axis by the operation of a c-glide plane, with N⋯O = 2.761 (3) Å and N—H⋯O = 165°. The mol­ecules are further linked by a weak C—H⋯O interaction, with C⋯O = 3.344 (4) Å and C—H⋯O = 150°. Pendant hydrogen-bonded ethanol solvent mol­ecules are attached to the chains by O—H⋯N hydrogen bonds, with O⋯N = 2.904 (3) Å and O—H⋯N = 175°.     

Reaction of 4,5-diamino-3-methyl-1-phenylpyrazole with 3-dimethylaminopropiophenones. Synthesis of new 4-aryl-6-methyl-8-phenyl-2,3-dihydropyrazolo[3,4-b]diazepines and 4-aryl-8-methyl-6-phenyl-2,3-dihydropyrazolo[4,3-b]diazepines

New 4-Aryl-6-methyl-8-phenyl-2,3-dihydropyrazolo[3,4-b]diazepines and 4-aryl-8-methyl-6-phenyl-2,3-dihydropyrazolo[4,3-b]diazepines were obtained from the reaction of 4,5-diamino-3-methyl-1-phenylpyrazole 1 with one equivalent of the 3-dimethylaminopropiophenones 2 in absolute ethanol. The structures of 4-aryl-6-methyl-8-phenyl-2,3-dihydropyrazolo[3,4-b]diazepines 3 and 4-aryl-8-methyl-6-phenyl-2,3-dihydropyrazolo[4,3-b]diazepines 4 were determined by detailed nmr measurements.     

Reaction of 4,5-diamino-1,6-dihydropyrimidin-6-ones with two equivalents of chalcones

The reaction of 4,5-diamino-1,6-dihydropyrimidin-6-ones 1 with two equivalents of the chalcones 2 leads in an acidic medium to the formation of the 2,3,6,7-tetrahydro-1H-pyrimido[4,5-b][1,4]diazepin-6-one derivatives 3a-d . The structure elucidation of the products is based on nmr measurements and an X-ray diffraction.     

8‐tert‐Butyl‐7‐(4‐chlorophenyl)‐10‐phenyl‐5,6‐dihydro‐10H‐benzo[h]pyrazolo[3,4‐b]quinoline

The title compound, C₃₀H₂₆ClN₃, crystallizes with Z′ = 3 in the P space group. The three independent molecules have very similar, although not identical, conformations, with almost perfect screw‐boat forms adopted by the non‐aromatic carbocyclic rings. Four independent C—H...π(arene) hydrogen bonds link the molecules into centrosymmetric six‐component aggregates.     

Synthesis and structural analysis of 5‐cyanodihydropyrazolo[3,4‐b]pyridines

Several new 3‐aryl‐5‐cyanopyrazolo[3,4‐b]pyridines were easily prepared from 3‐amino‐5‐arylpyrazoles and α‐cyanochalcones. Structural analysis using NMR solution studies revealed the 2H‐tautomers as the preferred tautomer in solution (DMSO‐d₆). X‐ray diffraction confirmed the 2H‐tautomers as the unique tau‐tomer species in the crystalline state as well. Geometry optimization of 1H and 2H‐tautomers at semi‐empirical levels (AM1, MINDO/3) were performed, indicating that in all cases the 2H‐tautomers are more stable than the corresponding 1H‐tautomers.     

Effect of thermal annealing on r.f. sputtering-deposited nanocrystalline GaN<Subscript><Emphasis Type="Italic">x</Emphasis></Subscript>As<Subscript>1−<Emphasis Type="Italic">x</Emphasis></Subscript> thin films

GaNAs thin films were deposited on Corning glass substrates by radio frequency (r.f.) sputtering in molecular nitrogen ambient. The stoichiometry in the GaNAs alloy was controlled by changing the nitrogen incorporation in the film during the growth process, through the variation of the r.f. power in the range 30–80 watts which produced films with N concentrations in the range: x = 0.85–0.90. The structural and optical properties of the GaNAs thin films were studied by X-ray diffraction (XRD), photoacoustic (PA) and photoluminescence (PL) spectroscopies. XRD measurements show a broad diffraction band with a peak close to the (002) diffraction line of the GaN hexagonal phase, and a slight shoulder at the position corresponding to the (111) GaAs cubic phase. The PA absorption spectra showed a remarkable shift to higher energies of the absorption edge as the r.f. power decreases corresponding to the films with higher N concentrations. Thermal annealing of the GaNAs films at temperatures of 450 °C produced a GaAs nanocrystalline phase with grain sizes in the range 10–13 nm, as confirmed by the XRD measurements that showed a well-defined peak in the (111) GaAs direction, and also by the PA spectra which showed an absorption band at energies around 1.45 eV due to the quantum confinement effects. PL spectra of thermal-annealed GaNAs films showed a very intense emission at 1.5 eV which we have associated to transitions between the first electron excited level and acceptor states in the GaAs nanocrystallites.     

Measuring the condensate fraction of rapidly rotating trapped boson systems: off-diagonal order from the density profile

We demonstrate a direct connection between the density profile of a system of ultracold trapped bosonic particles in the rapid-rotation limit and its condensate fraction. This connection can be used to probe the crossover from condensed vortex-lattice states to uncondensed quantum-fluid states that occurs in rapidly rotating boson systems as the particle density decreases or the rotation frequency increases. We illustrate our proposal with a series of examples, including ones based on models of realistic finite trap systems, and comment on its application to freely expanding boson density profile measurements.     

Universal intrinsic spin Hall effect

We describe a new effect in semiconductor spintronics that leads to dissipationless spin currents in paramagnetic spin-orbit coupled systems. We argue that in a high-mobility two-dimensional electron system with substantial Rashba spin-orbit coupling, a spin current that flows perpendicular to the charge current is intrinsic. In the usual case where both spin-orbit split bands are occupied, the intrinsic spin-Hall conductivity has a universal value for zero quasiparticle spectral broadening.     

Semiclassical spin transport in spin-orbit-coupled bands

Motivated by recent interest in novel spintronics effects, we develop a semiclassical theory of spin transport that is valid for spin-orbit coupled bands. Aside from the obvious convective term in which the average spin is transported at the wave packet group velocity, the spin current has additional contributions from the wave packet's spin and torque dipole moments. Electric field corrections to the group velocity and carrier spin contribute to the convective term. Summing all terms we obtain an expression for the intrinsic spin-Hall conductivity of a hole-doped semiconductor, which agrees with the Kubo formula prediction for the same quantity. We discuss the calculation of spin accumulation, which illustrates the importance of the torque dipole near the boundary of the system.     

A versatile synthesis of 4,5‐dihydropyrrolo[1,2‐a]quinoxalines

The reaction of 1‐(2‐aminophenyl)pyrrole with aromatic or heteroaromatic aldehydes in ethanol and catalytic amounts of acetic acid leads to 4,5‐dihydropyrrolo[1,2‐a]quinoxalines in high yields. When aliphatic aldehydes were used under the same conditions, a slow oxidation to the corresponding pyrrolo[1,2‐a]quinoxalines can occur; the oxidation can be avoided by preparing in situ the 5‐acetyl derivatives of the 4,5‐dihydropyrrolo[1,2‐a]quinoxalines.