Palladium catalyzed synthesis of tertiary allylamines. Utilization of α-nitro olefins as allylic nitro compounds

Reaction of α-nitro olefins with secondary amines in the presence of palladium(O) catalyst affords allylic amines.     

Photoinduced deformation of amphiphilic azo polymer colloidal spheres

Photoinduced shape deformation of colloidal spheres made of an amphiphilic azo polymer has been demonstrated in this work. The polymer contains the donor-and-acceptor-type azobenzene chromophores and can form uniform colloidal spheres by dropwise adding water into its THF solution. When the colloidal spheres obtained were exposed to the interfering p-polarized Ar+ laser beams (150 mW/cm2), the colloidal spheres changed to prolates (i.e., "rugby-balls"), "spindles", and finally "rods", depending on the irradiation times. The elongated direction of the spheres was observed to be the same as the polarization direction of the laser beam. The average major-to-minor ratio of the ellipsoids could be easily adjusted by controlling the irradiation time. The deformation effect observed in this work can offer a new way to prepare nonspherical colloids from colloidal spheres and will shed new light on the correlation between the photodriven shape deformation and photoinduced surface relief gratings for the same type of polymers.     

Study of the Fluorescence System of Europium–Enoxacin and its Applications

 This paper is the study of the fluorescence enhancement of Eu³⁺-1-ethyl-6-fluoro-4-oxo-7-(1-piperazinyl)-1,8-naphthyridin-3-carbonic acid (enoxacin, EFLX) system by surfactants. It was found that sodium dodecylbenzenesulfonate (SDBS) exhibits great enhancement on the fluorescence of the Eu-EFLX system. The molar ratio is 1:2:1 for Eu:EFLX: SDBS. Under the optimum conditions, the fluorescence intensity is a linear function of europium in the range of 1.0 × 10⁻⁸ ∼ 5.0 × 10⁻⁶ mol/L, the detection limit is 1.0 × 10⁻⁹ mol/L. The application of the Eu-EFLX-SDBS system for the determination of trace europium in rare earth samples gave satisfactory results. Received October 19, 2000. Revision August 10, 2001.     

Gaseous adsorption properties of a silica-pillared layered manganese oxide

Adsorptions of N(2), H(2)O, and organic vapors including CH(2)Cl(2), CCl(4), c-C(6)H(12), C(6)H(6), n-C(6)H(14), and n-C(9)H(20) on a silica-pillared layered manganese oxide (SiHMnO) and nonane-preadsorbed SiHMnO were examined. It is found that SiHMnO has a microporosity with a wide pore width distribution showing different pore wall affinities. Micropores with smaller width preferentially accommodate the nonane preadsorbate while the surface hydrophilicity of pore wall leads to an easier detachment of the adsorbed nonane molecules. H(2)O adsorption influences both the porosity and the surface properties by accelerating a sufficient hydrolysis of the remained TEOS molecules in SiHMnO. Examinations using Dubinin-Radeshkevich (DR) equation and isosteric heat of adsorption of organic molecules provide evidences that the wall surface of micropores with smaller and larger width have less affinity toward nonpolar and polar organic vapors, respectively.     

Noble gas-transition metal complexes: coordination of ScO+ by multiple Ar, Kr, and Xe atoms in noble gas matrixes

The combination of matrix isolation infrared spectroscopic and density functional calculation results provides strong evidence that the transition metal monoxide cation, ScO+, coordinates five noble gas atoms in forming the [ScO(Ng)5]+ (Ng = Ar, Kr, or Xe) complexes in noble gas matrixes.     

Diluent effects on the Debye-type dielectric relaxation in viscous monohydroxy alcohols

With the recognition that the Debye-type dielectric relaxation of liquid monohydroxy alcohols does not reflect the structural relaxation dynamics associated with the viscous flow and the glass transition, its behavior upon dilution is expected to differ from that of real alpha-processes. We have investigated the Debye-type dielectric relaxation of binary alcohol/alkane mixtures across the entire concentration range in the supercooled regimes. The focus is on 2-ethyl-1-hexanol in two nonpolar liquids, 3-methylpentane and squalane, which are more fluid and more viscous than the alcohol, respectively. The Debye relaxation is found to occur only for alcohol mole fractions x > 0.2 and is always accompanied by a non-Debye relaxation originating from the alcohol component. Prior to its complete disappearance, the Debye relaxation is subject to broadening. We observe that the Debye dynamics of 2-ethyl-1-hexanol is accelerated in the more fluid 3-methylpentane, while the more viscous squalane leads to longer Debye relaxation times. The present experiments also provide evidence that the breakdown of the Debye relaxation amplitude does not imply the absence of hydrogen-bonded structures.     

Compounds with symmetrical tricobalt chains wrapped by dipyridylamide ligands and cyanide or isothiocyanate ions as terminal ligands

Three new linear compounds of the type Co(3)(dpa)(4)X(2), where dpa is the anion of di(2-pyridyl)amine and X is NCS(-) (5), CN(-) (6), and N(CN)(2)(-) (7), have been prepared, and their structures and magnetic behavior have been studied. In all of them, including three different solvates of 5, the Co(3) chains are symmetrical with Co-Co distances of ca. 2.31-2.32 A. The appearance of four lines in the (1)H NMR spectra of the three compounds is also consistent with a symmetrical structure in solution. For all compounds, the magnetic behavior is quite similar with mu(eff) of ca. 1.9-2.0 micro(B) at temperatures between 1.8 and 200 K. As the temperature increases, the effective moments increase gradually, but since saturation is not reached, even at 400 K, the high-spin state cannot be assigned.     

Monte Carlo study of the pair correlation function for a liquid with non-central forces

The pair correlation function g(R), giving the probability that the centers of two nonspherical molecules are a distance R apart irrespective of their orientations, has been studied by the Monte Carlo method. The pair potential model studied is of the type u_o + u_a, where u_o is the isotropic Lennard-Jones (12,6) potential and u_a is either a dipole-dipole, quadrupole-quadrupole, or anisotropic overlap interaction. Dipolar and quadrupolar forces are found to have a small effect on g(R), whereas anisotropic overlap forces have a large effect.     

Melting behavior of one-dimensional zirconium nanowire

In this paper, we analyze the melting behavior of zirconium nanowire using the results of a series of molecular dynamics simulations. Our calculation employs a well-fitted, tight-binding many-body potential for zirconium atoms. The melting point of the nanowire is predicted by the root-mean-square displacements for inner and outer shells. Our simulations predict two melting behaviors: one is the inner melting and the other is the outer melting. Our results reveal that the melting of nanowire starts from the inner shell atoms. The melting point of zirconium nanowire is lower than the bulk value (2125 K). Moreover, the melting point of the inner shell is lower than that of the outer shell. A coexistence of crystal and liquid units is observed in the melting process of nanowire. An investigation of local clusters is carried out to further analyze the melting mechanism of the nanowire. The presence of the local clusters 1331, 1321, 1211, etc. is an indication of disordered structures. The pair and angular correlation functions are also presented for the analysis of the melting behavior. It is not only the diffusion of single atom but the diffusion of clusters result in the occurrence of the melting.