Probes for narcotic receptor mediated phenomena. Part 31: Synthesis of rac-(3R,6aS,11aS)-2-methyl-1,3,4,5,6,11a-hexahydro-2H-3,6a-methanobenzofuro[2,3-c]azocine-10-ol, and azocine-8-ol, the ortho-c and the para-c oxide-bridged phenylmorphan isomers

Two of the 12 possible oxide-bridged phenylmorphans, were synthesized, rac-(3R,6aS,11aS)-2-methyl-1,3,4,5,6,11a-hexahydro-2H-3,6a-methanobenzofuro[2,3-c]azocine-10-ol (7) (the ortho-c compound), and rac-(3R,6aS,11aS)-2-methyl-1,3,4,5,6,11a-hexahydro-2H-3,6a-methanobenzofuro[2,3-c]azocine-8-ol (8) (the para-c compound). Single-crystal X-ray diffraction studies indicated that the dihedral angle between the least squares planes through the phenyl ring and the atoms C₁, C_11a, C₁₂, and C₃ in the piperidine ring in both 7·CHCl₃ and 8·HBr was 6.9°. The C₁₂-C_6a-C_6b-C_10a torsion angle was found to be 139.3° for both compounds. The angular relationship between the phenolic ring and the piperidine ring in phenylmorphans that interact with specific opioid receptors as agonists or antagonists is of considerable theoretical interest.     

Controlling the Surface Functionalization of Ultrasmall Gold Nanoparticles by Sequence-Defined Macromolecules

Ultrasmall gold nanoparticles (diameter about 2 nm) were surface-functionalized with cysteine-carrying precision macromolecules. These consisted of sequence-defined oligo(amidoamine)s (OAAs) with either two or six cysteine molecules for binding to the gold surface and either with or without a PEG chain (3400 Da). They were characterized by ¹H NMR spectroscopy, ¹H NMR diffusion-ordered spectroscopy (DOSY), small-angle X-ray scattering (SAXS), and high-resolution transmission electron microscopy. The number of precision macromolecules per nanoparticle was determined after fluorescent labeling by UV spectroscopy and also by quantitative ¹H NMR spectroscopy. Each nanoparticle carried between 40 and 100 OAA ligands, depending on the number of cysteine units per OAA. The footprint of each ligand was about 0.074 nm² per cysteine molecule. OAAs are well suited to stabilize ultrasmall gold nanoparticles by selective surface conjugation and can be used to selectively cover their surface. The presence of the PEG chain considerably increased the hydrodynamic diameter of both dissolved macromolecules and macromolecule-conjugated gold nanoparticles.     

An Al(OTf)3-catalyzed environmentally benign process for the propargylation of indoles

Al(OTf)₃ catalyzed the alkylation of indoles using secondary/tertiary propargylic alcohols to produce 3-propargylated indoles in excellent yields with high selectivity. The reactions were performed in air with commercial grade solvents, and water was the only side product of the process. The catalyst was recovered after completion of the reaction and re-used with minimum loss of activity over three cycles.     

Probes for narcotic receptor-mediated phenomena. 33. Construction of a strained trans-5,6-ring system by displacement of a nitro-activated aromatic fluorine. synthesis of the penultimate oxide-bridged phenylmorphans

The synthesis of the ortho- and para-e isomers in the oxide-bridged 5-phenylmorphan series of rigid tetracyclic compounds was accomplished via rac-5-(2-fluoro-5-nitrophenyl)-2-methyl-2-azabicyclo[3.3.1]nonan-9beta-ol ((+/-)-10), an intermediate containing an aromatic nitro-activated fluorine atom. The fluorine atom was used as the leaving group for the formation of the strained tetracyclic trans-fused 5,6-ring system in rac-(1alpha,4aalpha,9aalpha)-1,3,4,9a-tetrahydro-2-methyl-6-nitro-2H-1,4a-propanobenzofuro[2,3-c]pyridine ((+/-)-11), although preference for cis ring fusion during the formation of tricyclic tetra- and hexahydrodibenzofurans has been well-documented. Single-crystal X-ray crystallographic study of the desired para-e isomer ((+/-)-2), as well as of two intermediates in its synthesis, provided assurance of the correct structures. The e-isomers are among the last of the 12 oxide-bridged 5-phenylmorphans to be synthesized. We envisioned the syntheses of these rigid, tetracyclic compounds in order to determine the three-dimensional pattern of a ligand that would enable interaction with opioid receptors as agonists or antagonists.     

Siloxanes with pendent naphthalene diimides: synthesis and fluorescence quenching

Cyclic siloxanes with pendent naphthalene diimide groups were synthesized via hydrosilylation to form amorphous electron-accepting compounds. Photophysical measurements and >99.9% fluorescence quenching of well-known p-type polymers by the siloxanes demonstrate that these siloxanes form a new class of highly efficient n-type materials that provide some control over intermolecular interactions.     

Horizontal Redistribution of Two Fluid Phases in a Porous Medium: Experimental Investigations

Classical models for flow and transport processes in porous media employ the so-called extended Darcy’s Law. Originally, it was proposed empirically for one-dimensional isothermal flow of an incompressible fluid in a rigid, homogeneous, and isotropic porous medium. Nowadays, the extended Darcy’s Law is used for highly complex situations like non-isothermal, multi-phase and multi-component flow and transport, without introducing any additional driving forces. In this work, an alternative approach by Hassanizadeh and Gray identifying additional driving forces were tested in an experimental setup for horizontal redistribution of two fluid phases with an initial saturation discontinuity. Analytical and numerical solutions based on traditional models predict that the saturation discontinuity will persist, but a uniform saturation distribution will be established in each subdomain after an infinite amount of time. The pressure field, however, is predicted to be continuous throughout the domain at all times and is expected to become uniform when there is no flow. In our experiments, we also find that the saturation discontinuity persists. But, gradients in both saturation and pressure remain in both subdomains even when the flow of fluids stops. This indicates that the identified additional driving forces present in the truly extended Darcy’s Law are potentially significant.     

A comparative study on structural,morphological and luminescence characteristics of Zn3(VO4)2 phosphor prepared via hydrothermal and citrate-gel combustion routes

Comparison of structural, morphological and spectroscopic properties of zinc vanadate Zn₃(VO₄)₂ phosphor synthesized via two different methods, viz. citrate-gel combustion and hydrothermal reaction, is presented. Highly crystalline and pure phase micro-rods are achieved by citrate-gel combustion route. The hydrothermal reaction products exhibit ribbon like structures. X-ray photoelectron spectroscopic investigation reveals the presence of multiple oxidation states of vanadium in the hydrothermally synthesized phosphor. Luminescence properties have also been compared and the effect of divalent cationic substitution (Ca, Mg) is presented.     

The effects of fractional order on a 3-D quadratic autonomous system with four-wing attractor

In this paper, a fractional 3-dimensional (3-D) 4-wing quadratic autonomous system (Qi system) is analyzed. Time domain approximation method (Grunwald–Letnikov method) and frequency domain approximation method are used together to analyze the behavior of this fractional order chaotic system. It is found that the decreasing of the system order has great effect on the dynamics of this nonlinear system. The fractional Qi system can exhibit chaos when the total order less than 3, although the regular one always shows periodic orbits in the same range of parameters. In some fractional order, the 4 wings are decayed to a scroll using the frequency domain approximation method which is different from the result using time domain approximation method. A surprising finding is that the phase diagrams display a character of local self-similar in the 4-wing attractors of this fractional Qi system using the frequency approximation method even though the number and the characteristics of equilibria are not changed. The frequency spectrums show that there is some shrinking tendency of the bandwidth with the falling of the system states order. However, the change of fractional order has little effect on the bandwidth of frequency spectrum using the time domain approximation method. According to the bifurcation analysis, the fractional order Qi system attractors start from sink, then period bifurcation to some simple periodic orbits, and chaotic attractors, finally escape from chaotic attractor to periodic orbits with the increasing of fractional order α in the interval [0.8,1]. The simulation results revealed that the time domain approximation method is more accurate and reliable than the frequency domain approximation method.     

A four-wing chaotic attractor generated from a new 3-D quadratic autonomous system

This paper introduces a new 3-D quadratic autonomous system, which can generate two coexisting single-wing chaotic attractors and a pair of diagonal double-wing chaotic attractors. More importantly, the system can generate a four-wing chaotic attractor with very complicated topological structures over a large range of parameters. Some basic dynamical behaviors and the compound structure of the new 3-D system are investigated. Detailed bifurcation analysis illustrates the evolution processes of the system among two coexisting sinks, two coexisting periodic orbits, two coexisting single-wing chaotic attractors, major and minor diagonal double-wing chaotic attractors, and a four-wing chaotic attractor. Poincaré-map analysis shows that the system has extremely rich dynamics. The physical existence of the four-wing chaotic attractor is verified by an electronic circuit. Finally, spectral analysis shows that the system has an extremely broad frequency bandwidth, which is very desirable for engineering applications such as secure communications.