Synthesis,Characterization, DFT Calculations and Non-linear Optical Properties of a New Organic–Inorganic Arsenate

This paper undertakes the synthesis by slow evaporation method at room temperature of a new organic–inorganic hybrid material with the general formula [C₁₂H₁₃N₂O]H₂AsO₄. The newly developed hybrid is characterized by X-ray single crystal diffraction, Infrared, Raman spectroscopy and density functional theory (DFT) calculations. At ambient temperature, this compound crystallizes in the non-centrosymmetric space group P2₁2₁2₁ of the orthorhombic system. The structural arrangement is formed by infinite anionic chains extending parallel to the direction [100]. The organic entities are linked to these chains by N–H···O type hydrogen bonds which play an important role in the cohesion of the one-dimensional network. The optimized molecular structure, vibrational spectra and the optical properties were calculated by the DFT method using the B3LYP function with the LanL2DZ basis set. The vibrational wavenumbers were evaluated for this compound by using transferable scale factor. The first hyperpolarizability value β_tot of the title compound is equal to 15.94?×?10^?31 esu. Hence, the large β value calculated by the B3LYP method shows that the studied compound is a good NLO material and is suitable for future non-linear optical studies. The HOMO–LUMO energy gap and other related molecular properties are going to be discussed and reported later.     

Synthesis and structure determination of a 2D open-framework zincophosphate templated by cyclohexylamine molecules

The synthesis and crystal structure of a new bidimensional zincophosphate (ZnPO) are reported. Zn₂(HPO₄)₂Cl₂·2NC₆H₁₄ crystallizes in the monoclinic space group P2₁/a (n°14) with a = 8.830(3) Å, b = 9.278(3) Å, c = 26.950(9) Å, = 90.74(3)°, V = 2207.7(1) ų and Z = 4. This new material consists of a 2D open-framework of corner sharing ZnO₃Cl and PO₃OH tetrahedra alternating with planes of protonated cyclohexylamine molecules (NC₆H₁₄)⁺. The organic molecules are interconnected to the framework through hydrogen bonds.     

Novel Monolithic Stationary Phase with Surface-Grafted Triphenyl Selector for Reversed-Phase Capillary Electrochromatography

A triphenylmethylamine-functionalized monolithic capillary column was newly designed for reversed-phase capillary electrochromatographic applications. Incorporation of the three phenyl rings-containing selector (also referred to as trityl selector) was achieved through post-polymerization functionalization of a generic monolithic matrix bearing nucleophilic-sensitive hydroxysuccinimide moieties. Such a 3D polymer matrix was obtained through UV-induced in situ free radical copolymerization of N-acryloxysuccinimide and ethylene dimethacrylate. The separation properties of the trityl monolithic capillary column were initially evaluated vis-à-vis polycyclic aromatic hydrocarbons, as model hydrophobic compounds, and compared to the separation ability of a benzylamine-functionalized monolithic capillary column prepared using the same generic monolithic matrix. Electrochromatographic separation of phenols and anilines was also considered, and our preliminary results suggest the occurrence of hydrophobic interactions due to the aromatic and non-polar nature of the surface-grafted trityl selector. The triphenyl monolithic capillary column exhibited relative standard deviation values (% RSD) below 4.1 % for the here-studied chromatographic parameters, namely, retention factor, selectivity, resolution, and efficiency.

     

Synthesis,Crystal Structure,and Characterization of A New Adduct Bis-(2-Amino-3-Benzyloxypyridinium) Selenate Monohydrate [C12H13N2O]2SeO4.H2O

Abstract

A new adduct bis-(2-amino-3-benzyloxypyridinium) selenate monohydrate, [C₁₂H₁₃N₂O]₂SeO₄.H₂O, has been synthesized by slow evaporation at room temperature using 2-amino-3-benzyloxypyridine as the structure-directing agent. The structure, determined by single-crystal X-ray diffraction at 298 K, can be described as organic-inorganic tunnels with different forms built by infinite inorganic chains parallel to the c axis and connected to the organic cations. In this atomic arrangement, hydrogen bonds and van der Waals interactions between the different species play an important role in the tri-dimensional network cohesion. Solid-state ¹³C and ⁷⁷Se MAS NMR spectroscopy results are in agreement with the X-ray structure.

[Supplementary materials are available for this article. Go to the publisher's online edition of Phosphorus, Sulfer, and Silicon and the Related Elements for the following free supplemental files: Additional figures and tables.]     

Ruthenium-catalyzed enantioselective hydrogenation of aryl-pyridyl ketones

Various substituted aryl-pyridyl ketones were hydrogenated in the presence of Ru-XylSunPhos-Daipen bifunctional catalytic system with enantiomeric excesses up to 99.5%. Upon introduction of a readily removable ortho-bromo atom to the phenyl ring, enantiomerically enriched 4-chlorophenylpyridylmethanol was obtained by hydrogenation method with 97.3% ee, which provided an important chiral intermediate for some histamine H(1) antagonists.     

Catechol derivatives-coated Fe3O4 and γ-Fe2O3 nanoparticles as potential MRI contrast agents

Superparamagnetic iron oxide nanoparticles, Fe₃O₄ and γ-Fe₂O₃, were produced by the so-called polyol process. In order to stabilize the particles in a physiological environment as potential contrast agents for Magnetic Resonance Imaging (MRI), the as-prepared particles were successfully transferred to an aqueous medium through ligand exchange chemistry of the adsorbed polyol species with the dopamine or the catechaldehyde. The ligands were able to participate in bidentate binding to the nanoparticles surface and to improve the stability of aqueous suspensions of the nanoparticles. Analysis was performed by various techniques including X-ray diffraction, transmission electron microscopy, infrared spectroscopy and thermal analysis. The results of magnetic measurements and initial in vitro magnetic resonance imaging essays are presented for the pre- and post-surface modified nanoparticles, respectively and discussed in relation with their structure and microstructure.     

The fluid limit of the multiclass processor sharing queue

Consider a single server queueing system with several classes of customers, each having its own renewal input process and its own general service times distribution. Upon completing service, customers may leave, or re-enter the queue, possibly as customers of a different class. The server is operating under the egalitarian processor sharing discipline. Building on prior work by Gromoll et al.?(Ann. Appl. Probab. 12:797?C859, 2002) and Puha et al.?(Math. Oper. Res. 31(2):316?C350, 2006), we establish the convergence of a properly normalized state process to a fluid limit characterized by a system of algebraic and integral equations. We show the existence of a unique solution to this system of equations, both for a stable and an overloaded queue. We also describe the asymptotic behavior of the trajectories of the fluid limit.     

Ru-catalyzed highly chemo- and enantioselective hydrogenation of γ-halo-γ,δ-unsaturated-β-keto esters under neutral conditions

Finely-tuned ruthenium-catalyzed highly chemoselective and enantioselective hydrogenation of γ-halo-γ,δ-unsaturated-β-keto esters at the carbonyl group was achieved under neutral reaction conditions (ee up to 97%). Both olefin and alkenyl halogen moieties, which are labile under hydrogenation conditions, remained untouched during the reaction.     

Resonance scattering on In impurity in Pb0.4Sn0.6Te solid solutions

The Hall coefficient and resistivity were measured on a series of samples of InTe in Pb_0.4Sn_0.6Te solid solutions with varying indium content from 0 to 5 molar%. All samples show a p-type conductivity with the concentration of holes 10¹⁹ cm⁻³ at 77 K. A considerable decrease of mobility calculated from the measurements was observed in the samples with high content of In. The contribution to the mobility, directly related to the scattering of holes into In atoms, was determined, and the scattering crosssection was estimated. We observed a drastic increase in the scattering crosssection with the rise of In content, which can be explained by the resonance scattering of holes into the band of quasi-local states of In. This result can also be explained with the use of the Breit–Wigner formula. The location of the In states in the valence band was also calculated using the Kane model.