Structure of 2-[(Phenyl)-(3,5-Dimethyl-Pyrazol-1-yl)-Methyl]-Malonic Acid Diethyl Ester

Abstract  

The titled new functionalized ligand of type 2-[(phenyl)-(3,5-dimethyl-pyrazol-1-yl)-methyl]-malonic acid diethyl ester (4) is prepared in good yield through condensation of 3,5-dimethyl-pyrazole, with 2-arylidene-malonic acid diethyl esters 3. The structure of 4 was determined by spectral (IR, ¹H and ¹³C NMR), elemental analyses and X-ray diffraction data. The title compound (4) crystallizes in the monoclinic space group P2₁/a, with a = 7.9253 (2), b = 17.1299 (5), c = 13.4522 (4) ?, β = 90.220 (2)°, V = 1,826.25 (9) ?³, Z = 4 and with R _int = 0.021. The molecular conformation shows two possible pockets ready to coordinate two metal atoms. The crystal structure of (4) is stabilized by inter-molecular C–H⋯O and C–H⋯N hydrogen bonding.     

Synthesis,characterization and coordination chemistry of substituted β-amino dicarbonyls

An efficient and facile method for the synthesis of novel structurally diverse β-amino dicarbonyl compounds is described by exploring the aza-Michael addition reaction in an aqueous medium as a key step. Thereby, 2-(aryl-disubstituted-amino-1-yl-methyl)-malonic acid diethyl esters were achieved in a good to excellent yields. These products were easily isolated with enough purity just by using simple recrystallization. The crystals of the compounds (17) and (24) have been obtained and studied by X-ray crystallographic analyses.     

To(Γ) phonons in GaAs under uniaxial strain

Using the density-functional theory in the local-density approximation, norm-conserving pseudopotentials, and plane-wave expansions, we have developed a simple way to calculate ab initio the uniaxial strain dependence of the TO(Γ) phonon mode in GaAs, including the envolved relaxations effects. The relaxation response of the system was evaluated from the use of the elasticity theory. Our results confirm the experimental evidence and show a reasonable agreement with the observed data for the frequency splitting of this phonon mode. © 1993 John Wiley & Sons, Inc.     

Porous silicon as functionalized material for immunosensor application

Recently, for sensor application, porous silicon has received a great deal of attention due to the high specific surface area and the easy fabrication using some established processes of the usual silicon technology. We herein, report the development of a novel immunosensors based on porous silicon for antigen detection. The multilayer immunosensor structure was fabricated following the successive steps: APTS self-assembled monolayer (SAM) layer, glutaaldehyde linker, anti-rabbit IgG binding. The insulating properties of the aminopropyl-triethoxysilane (APTS) monolayer were studied with cyclic voltammetry and the molecular structure was characterized with Fourier-transform infrared (FTIR) technique. The binding between antibody and different antigen concentration (rabbit IgG) was monitored by measuring the capacitance-voltage curve of the antibody functionalized EIS structure. A detection limit of 10 ng/ml of antigen can be detected.     

Vibrational and thermal properties of ScN and YN: quasi-harmonic approximation calculations and anharmonic effects

The structural, vibrational and thermal properties of rocksalt ScN and YN are investigated by using a first-principles plane-wave approach. The results are discussed in comparison with the similarly calculated results for rocksalt MgO and zincblende AlN. The thermal expansivity (α(V)) computed within the quasi-harmonic approximation shows that there are significant anharmonic effects in ScN and YN, which are comparable to those in MgO. Since no experimental results are available for α(V) of either ScN or YN, the anharmonic effects are accounted for by a variant of the very recently introduced effective semiempirical ansatz (Phys. Rev. B 2009 79 104304) for calculating anharmonic free energy, which does not require any input from experiment. The validity of this very simple approach is demonstrated first by applying it to MgO. For the considered phase of AlN, the quasi-harmonic approximation is valid up to very high temperatures, and the thus obtained α(V) is in good agreement with experiment. The values of α(V) for semiconductor transition metal nitrides that crystallize in the rocksalt phase are higher than those for the zincblende phase of group-IIIB nitrides, and a major part of these differences is due to the crystal structure.     

Dielectric behaviour of copolymers based on 2,2,2-trifluoroethyl methacrylate and cyano co-monomers

In the frame of a research aiming at developing new dielectric polymers containing CCN and CF substituents with strong dipole moment, statistical copolymers based on cyano monomers such as acrylonitrile (AN), methacrylonitrile (MAN), methylvinylidene cyanide (MVCN) and 2,2,2-trifluoroethylmethacrylate (MATRIF), were synthesized and characterized. Elemental analysis has shown that the molar percentages of AN and MAN in the copolymers were 45 mol.%, while only 5 mol.% of MVCN was incorporated in the poly(MVCN-co-MATRIF) copolymer. These copolymers exhibit glass transition temperatures, T_g, in the range of 70-90 °C. The dynamic dielectric analyses and their complex permittivities of these copolymers were studied versus the temperature and the frequency. Evidence of an α-relaxation phenomenon in the glass transition region, which is confirmed by the Vogel-Fulcher-Tammann (VFT) temperature dependence of the relaxation times, was assigned to the cooperative reorientation motions of the cyano groups. The values of dielectric strength (Δε) for the copolymers based on MATRIF were determined by Havriliak-Negami (HN) fitting from the dispersion curves, and can be related to the polarity of the monomer unit and to the packing of the macromolecular chains. These relaxations are sometimes overlapped by conduction phenomena due to ionic impurities at low frequencies and high temperatures dipolar losses. In the glassy state, the permittivity values of AN and MAN copolymers show an increase of polarity which makes them candidates for some applications amongst advanced electrical materials such as dielectric layer for capacitors.     

Crystal Structure of Diethyl[(4chlorophenyl)(dibenzylamino)methyl]propanedioate

Abstract  

The titled new functionalized N,O,O-ligand of type diethyl[(4-chlorophenyl)(dibenzylamino)methyl]propanedioate (4) is prepared in good yield through condensation of dibenzylamine, with 2-arylidene-malonic acid diethyl esters 3. The structure of 4 was determined by spectral (IR, ¹H NMR), elemental analyses and X-ray diffraction data. The molecular conformation shows two possible pockets ready to coordinate two metal atoms.