ResonanceRaman spectra of Iron(II) complexes with 4,4′-didodecyloxy-2,2′-bipyridine and 4,4′-dioctadecyloxy-2,2′-bipyridine

The resonanceRaman spectra of Fe(LC ₁₂)₃Cl₂ and Fe(LC ₁₈)₃Cl₂ (whereLC ₁₂ andLC ₁₈ denote 4,4′-didodecyloxy-2,2′-bipyridine and 4,4′-dioctadecyloxy-2,2′-bipyridine, respectively) have been measured along with their excitation profiles. The exciting lines of an Ar⁺ laser have been used. The bands appearing in theRR spectra within 1 200–1 600cm^?1 (expected to arise from thebipy moiety C-N and C-C vibrations) suffer the greatest resonance enhancements. Both depolarization ratios of theRaman bands and excitation profiles reveal the interaction of the resonant electronic states.     

Coordination chemistry of H-spirophosphorane ligands towards pentacarbonylchlororhenium(I) – synthesis,structure and catalytic activity of complexes

Synthesis of a group of carbonyl rhenium coordination compounds with hydrospirophosphorane ligands was carried out and described. Different symmetrical HP(OCH₂CH₂NH)₂ L1 , HP(OCH₂CMe₂NH)₂ L2 , HP(OC₆H₄NH)₂ L3 , and unsymmetrical ligands HP (OCMe₂CMe₂O)(OC₆H₄NH) L4 were found to coordinate to the rhenium center as bidentate P,N donor ligands yielding fac-[ReCl (CO)₃ Ln ], where n = 1 – 4. Furthermore, monodentate coordination was also observed in some cases, as was clearly presented in the case of [ReCl(CO)₂( L4- κ²P,N)( L4- κP)] complex. All of the complexes were characterized using optical spectroscopy. Single-crystalX-ray diffraction was also performed in the case of fac-[ReCl(CO)₃ L3 ], fac-[ReCl(CO)₃ L4 ], [Re(CO)₂( L2 )₂]Cl and [ReCl (CO)₂( L4- κ²P,N)( L4- κP)] samples. Complexes [ReCl(CO)₃ L3 ] and [ReCl (CO)₃ L4 ], both bearing rings of conjugated double bonds within hydrospirophosphorane ligands, exhibited luminescence. Catalytic properties of rhenium complexes were assessed using the representative fac-[ReCl (CO)₃ L2 ] complex in the dimerization reaction of terminal alkynes. An efficient and selective procedure for synthesis of the E - enynes was developed. Coupling of (2-chlorophenyl)acetylene was mediated by [ReCl (CO)₃ L2 ]/TBAF system with a 100% conversion rate. Different substituents within aromatic alkynes were tolerated and the resulting products were dependent on the nature of the substituents.     

Gas chromatographic analysis of 1,4-naphthoquinones

Summary A gas chromatographic method is described for the analysis of 1,4-naphthoquinone derivatives in the mixtures of their isomers. The best results were obtained using 7.5% XE-60 on Chromosorb G at 180°. Quantitative determination was carried out with 1,4-naphthoquinone as the internal standard and using relative response factors or by means of the direct calibration method.     

Organocatalytic asymmetric addition of aliphatic thiols to nitro olefins and nitrodienes

The N-3,5-bis(trifluoromethyl)phenyl thiourea derivative of readily available chiral 1-benzyl-3-aminopyrrolidine was an effective organocatalyst for the asymmetric sulfa-Michael reaction. The adducts of aliphatic thiols to nitro olefins and nitrodienes were formed in good yields and with up to 87% ee in the presence of 2.5 mol % of the organocatalyst.     

Chiral benzisoselenazolones: conformational analysis based on experimental and DFT calculated Se NMR

A series of new enantiomeric N-substituted benzisoselenazol-3(2H)-ones were prepared from 2-(chloroseleno)benzoyl chloride and 9-amino-deoxyquinine (both 9-native and 9-epi) as well as the other chiral primary amines. The ⁷⁷Se NMR parameters for the obtained benzisoselenazolones were measured and theoretically calculated at the DFT level of theory using B97-2 hybrid functional and cc-pVTZ basis set. The DFT ⁷⁷Se chemical shifts for the lowest energy conformers were in agreement with the experimental data, while the conformers of higher energy showed markedly worse fit. Interestingly, the preferred conformation for 2-(1-arylalkyl)-benzisoselenazolones is the gauche type (Se–N–C–H≈±180°), and it is in agreement with those observed in crystals (X-ray). The calculation predicts a much higher sensitivity for the ⁷⁷Se chemical shift of the conformation than for the corresponding ¹³C data. In the ⁷⁷Se NMR spectra of chiral benzisoselenazolones with added racemic or l-N-Boc-phenylglycine, chiral discrimination could not be observed mostly due to signal broadening. In the ¹H NMR spectra, the benzisoselenazole derived from epi-9-amino-deoxyquinine induced splittings of the amino acid signals, thus allowing for discrimination of the enantiomers.     

Application of DIC Technique to Concrete—Study on Objectivity of Measured Surface Displacements

The measurements of the width of a localized zone on the surface of notched concrete beams under quasi-static three-point bending were performed using the 2D Digital Image Correlation technique. Different image length resolutions, image search patches and distances between search patch centres were tested. Attention was paid to the accuracy and objectivity of surface displacements measured. An original method was proposed to determine the width of localized zones above the notch based on experiments.     

Calculations of fracture process zones on meso-scale in notched concrete beams subjected to three-point bending

The paper describes investigations on fracture process zones (FPZ) at meso-scale in notched concrete beams subjected to quasi-static three-point bending. The simulations were carried out with the FEM using isotropic damage constitutive model enhanced by a characteristic length of micro-structure by means of a non-local theory. Concrete was modelled as a random heterogeneous three-phase material. The effect of the beam size, aggregate distribution, aggregate density, aggregate shape, aggregate size and characteristic length on the width and shape of FPZ and load-displacement curve was numerically investigated. The numerical results were compared with own test results using Digital Image Correlation method (Skar?yński et al., 2009a), the tests by Le Bellěgo et al., (2003) and the size effect law by Ba?ant (2004).     

Cerium catalyzed persulfate oxidation of polycyclic aromatic hydrocarbons to quinones

A practical synthesis of polycyclic quinones from the parent hydrocarbons is described. The twophase oxidation of hydrocarbons was accomplished by using ammonium persulfate in the catalytic presence of cerium ammonium sulfate, silver nitrate, and sodium dodecyl sulfate. The reaction conditions and scope have been discussed in detail.     

Determination of benzo[a]pyrene in shale oil-by solid-surface fluorescence

A method has been developed for determining benzo[a]pyrene in shale oil by combining dry-column chromatography, thin-layer chromatography and fluorescence spectrometry. A two-step separation method was employed to isolate benzo[a]pyrene from shale oil. Benzo[a]pyrene was identified and determined by detecting its fluorescence directly from chromatoplates; as little as 0.06 ng can be detected. The limit of detection of benzo[a]pyrene in shale oil is ca. 1.2 ppm and the reproducibility of the method is ±2.6 ppm.     

Cyclization of 1,3-diaryl-3-phenylsulfanyl-1-propanols to thiochromans with the participation of [1,3]-PhS shift

Optically active (3R,1RS)-3-aryl-1-phenyl-3-phenylsulfanyl-1-propanols were easily dehydrated forming mainly rac-cis-2-aryl-4-phenylthiochroman, and rac-cis-4-aryl-2-phenylthiochroman along with the corresponding trans-isomers. The observed reaction outcome (rearrangement and racemisation) apparently results from the S_EAr reaction involving the unusual 1,3-phenylsulfanyl group migration. This interpretation is supported by the results of theoretical studies (DFT) on the supposed intermediates.