Structure and reflective properties of Al-Cu-Fe quasicrystalline thin film prepared by laser induced arc method

Al-Cu-Fe thin films were prepared by laser induced arc (laser-arc) method from a single source-Al63Cu25Fe12 alloy, which was proved to consist of quasicrystalline phase together with approximant phase. The composition of the deposited films meets the requirement for formation of icosahedral symmetry phase. Quasicrystalline phase was obtained after annealing the amorphous as-deposit film samples. The optical properties of the samples were investigated. Thin film samples of Al, Cu and Fe deposited under the same condition were employed for comparison. The results showed specific reflective properties of Al-Cu-Fe quasicrystal thin film in some wavelength range. The optical conductivity of the films exhibited a negative peak, centered about 440 nm in range of 190to 800 nm. The Al-Cu-Fe quasicrystal thin films could absorb almost all the ray in the wavelength range from 420nm to 450 nm. The ratio of absorption was greater than 99%.     

THE PREPARATION AND STABILITY OF COLLOIDAL METAL DISPERSIONS PREPARED BY A TWO-PHASE NON-AQUEOUS ROUTE

Stable suspensions of small metal Au, Ru, PI, Pd, Rh, Co and Nl particles dispersed in n-heptane and n-dodecane have been prepared using a novel two-phase system, Involving the formation of the particles In a methanolic phase and subsequent phase transfer of the panicles to the alkane medium. The dispersions consisted of small particles having diameters In the range of 8-30 nm (the gold sols were very polydlsperse having average diameters of ca.34 nm). The phase transfer of the particles and their subsequent colloid stability were effected by the presence of dissolved dispersant in the hydrocarbon phase (either Oloa 1200 or Hypermer LP 8). In the case of Oloa 1200, a widely-used polylsobutylene succinimide automotive engine dispersant, It Is proposed that the amlne groups adsorb strongly to the acidic surface o1 the particles, and the 70-carbon polyisobutylene chains extend Into the hydrocarbon medium sufficiently to maintain the separation of adjacent particles by steric and possibly also by electrical repulsion.     

Trifluoromethanesulfenyl acetate, CF3S-OC(O)CH3, and trifluoromethanesulfenyl trifluoroacetate, CF3S-OC(O)CF3: unexpected conformational properties

Structural and conformational properties of two sulfenyl derivatives, trifluoromethanesulfenyl acetate, CF3S-OC(O)CH3 (1), and trifluoromethanesulfenyl trifluoroacetate, CF3S-OC(O)CF3 (2), were determined by gas electron diffraction, vibrational spectroscopy, in particular with IR (matrix) spectroscopy, which includes photochemical studies, and by quantum chemical calculations. Both compounds exist in the gas phase as a mixture of two conformers, with the prevailing component possessing a gauche structure around the S-O bond. The minor form, 15(5)% in 1 and 11(5)% in 2 according to IR(matrix) spectra, possesses an unexpected trans structure around the S-O bond. The C=O bond of the acetyl group is oriented syn with respect to the S-O bond in both conformers. UV-visible broad band irradiation of 1 and 2 isolated in inert gas matrixes causes various changes to occur. Conformational randomization clearly takes place in 2 with simultaneous formation of CF3SCF3. For 1 the only reaction channel detected leads to the formation of CH3SCF3 with the consequent extrusion of CO2. Quantum chemical calculations (B3LYP/6-31G and MP2 with 6-31G and 6-311G(2df,pd) basis sets) confirm the existence of a stable trans conformer. The calculations reproduce the conformational properties for both compounds qualitatively correct with the exception of the B3LYP method for compound 2 which predicts the trans form to be prevailing, in contrast to the experiment.     

Photoisomerization of matrix-isolated bis(trifluoromethyl) sulfoxide: formation of the sulfenic ester CF3SOCF3

Bis(trifluoromethyl) sulfoxide, CF(3)S(O)CF(3), isolated in noble gas matrixes at low temperatures, isomerizes upon UV irradiation into the sulfenic ester CF(3)SOCF(3). The new species is characterized spectroscopically, and the vibrational assignment is supported by (18)O isotopic labeling experiments and by DFT calculations. The calculated structural parameters of CF(3)SOCF(3) are compared with the calculated and experimental data of the related compounds CF(3)SSCF(3) and CF(3)OOCF(3). In addition, the computed enthalpy differences between the sulfoxide R(2)S=O and sulfenate RSOR structures for R = H, F, CH(3), and CF(3) are included.     

Weak and strong hydrogen bonds conducting the supramolecular framework of 1-butyl-3-(1-naphthoyl)thiourea: crystal structure,vibrational studies,DFT methods,Pixel energies and Hirshfeld surface analysis

A detailed structural and spectroscopic study of a new thiourea derivative 1-butyl-3-(1-naphthoyl)thiourea (1) is presented with the assistance of theoretical calculations. The X-ray diffraction structure analysis reveals a planar carbonylthiourea group, favoured by intra-molecular NH···O bond. The compound is arranged in the lattice as NH···O and NH···S bonded polymeric ribbons, that extend along the crystal b-axis. Molecular pairs involving N–H···S hydrogen bonds are a dominant contribution to packing stabilisation coming from coulombic component. Hirshfeld surfaces and two-dimensional-fingerprint plots show different intermolecular contacts and its relative contributions to total surface in each compound. The AIM approach shows the nature and strength of the strong and weak intramolecular interactions and the solvent effect, while NBO analysis reveals that the sulphur atom is responsible for the higher hyperconjugative stabilising energy.     

2-Chloroethylisocyanate. Thermal decomposition and spectroscopic properties

2-Chloroethylisocyanate has been studied in a thorough way. NMR, Raman, FTIR, and Ar-matrix vibrational spectra of the molecule are presented and discussed with the complement of ab initio and DFT methods. The spectroscopic results reveal the existence of anti and gauche conformers that are equally populated in the gas phase. Thermal decomposition between 393 and 648 K shows two different pathways depending on the temperature, which can be interpreted in terms of simple second- and first-order mechanisms, respectively. Quantum mechanical calculations reproduce the experimental results.     

Chlorodifluoroacetyl cyanide, ClF2CC(O)CN: synthesis, structure, and spectroscopic characterization

The novel molecule difluorochloroacetyl cyanide, ClF(2)CC(O)CN, has been characterized by IR (gas phase, Ar matrix), Raman (liquid), (19)F and (13)C NMR, and photoelectron (PES) spectroscopies; photoionization mass spectrometry (PIMS); and gas electron diffraction (GED). The conformational properties of ClF(2)CC(O)CN have been studied by joint application of vibrational spectroscopy, GED, and quantum chemical calculations. The existence of two conformers is detected in the gas and liquid phases, in which the C-Cl bond adopts gauche and syn orientations with respect to the C═O group. The computed enthalpy difference is in harmony with the experimental results of the gauche being more stable than the syn conformer by ΔH° = 1.3 kcal mol(-1) (MP2/cc-pVTZ). The valence electronic properties and the possible ionization and dissociation processes of the title compound are studied using the PES and PIMS. The experimental first vertical ionization energy of 12.0 eV corresponds to the ejection of an electron of the oxygen lone pairs. Taking into account the properties and broad applications of acyl cyanides, ClF(2)CC(O)CN is a promising new precursor in preparative chemistry.     

S-(fluoroformyl)O-(trifluoroacetyl) thioperoxide, FC(O)S-OC(O)CF3: gas-phase structure and conformational properties

The geometric structure and conformational properties of S-(fluoroformyl)O-(trifluoroacetyl) thioperoxide, FC(O)S-OC(O)CF3, were investigated by gas electron diffraction, matrix isolation infrared spectroscopy, and quantum chemical calculations (B3LYP with the 6-31G and aug-cc-pVTZ basis sets and MP2 with the 6-31G basis set). The experimental methods result in a mixture of two conformers with gauche conformation around the S-O bond. In the main conformer (82(7)% according to GED at 298 K), the C=O bond of the FC(O) group is oriented syn with respect to the S-O bond and phi(C-S-O-C) = 75(3) degrees . In the minor conformer (18(7)%), this C=O is oriented anti. Both conformers possess syn orientation of the C=O bond of the CF3C(O) group. The conformational properties and geometric parameters are reproduced reasonably well by the quantum chemical calculations, except for the S-O bond length, which is predicted too long by 0.04 A (B3LYP/aug-cc-pVTZ).