Search results for "Spectroscopy"
showing 10 items of 10293 documents
Structure and fluxional behaviour of heptaleneirontricarbonyl and heptalenebis (Irontricarbonyl)
1987
Abstract The synthesis of heptaleneirontricarbonyl ( 4 ) is described. The structures of 4 and of the closely related heptalenebis(irontricarbonyl) ( 3 ) are elucidated by NMR spectroscopy ( 1H and 13C) and by X-ray crystallography. Compounds 3 and 4 are shown by dynamic NMR to undergo an isodynamic 1 ,2-migration of the Fe(CO3)-groups as well as a carbonyl scrambling. The relevant kinetic data allow for a mechanistic discussion of the dynamics and a comparison with other irontricarbonyl complexes.
Synthesis and biopharmaceutical characterisation of new poly(hydroxyethylaspartamide) copolymers as drug carriers.
2001
Abstract Four new poly(hydroxyethylaspartamide)-based copolymers bearing (a) poly(ethylene glycol) 2000, (b) poly(ethylene glycol) 5000, (c) poly(ethylene glycol) 2000 and hexadecylalkyl, (d) poly(ethylene glycol) 5000 and hexadecylalkyle, as pendant groups were synthesised. The copolymers were obtained by partial aminolysis of polysuccinimide with poly(ethylene glycol) and hexadecylalkyl amino derivatives followed by reaction with ethanolamine. Naked polyhydroxyaspartamide was obtained by polysuccinimide reaction with ethanolamine. The nuclear magnetic resonance, infrared, light scattering and elemental analysis allowed for the extensive physico-chemical characterisation of the carriers. T…
Geometric and electronic structure of dithiapyranylidine: evolution upon oxidation
1993
Abstract We present a theoretical investigation of the modifications that successive oxidation induces on the geometric and electronic structures of the π-electron donor dithiapyranylidene. The lengthening of the double bonds and the shortening of the single bonds calculated as the molecular charge increases indicate a gain of aromaticity with oxidation. Both the geometricand the electronic structure of dithiapyranylidene show a clear evolution towards those of biphenyl as oxidation takes place.
Group 13 complexes of dipyridylmethane, a forgotten ligand in coordination chemistry.
2015
The reactions of dipyridylmethane (dpma) with group 13 trichlorides were investigated in 1 : 1 and 1 : 2 molar ratios using NMR spectroscopy and X-ray crystallography. With 1 : 1 stoichiometry and Et2O as solvent, reactions employing AlCl3 or GaCl3 gave mixtures of products with the salt [(dpma)2MCl2](+)[MCl4](-) (M = Al, Ga) as the main species. The corresponding reactions in 1 : 2 molar ratio gave similar mixtures but with [(dpma)MCl2](+)[MCl4](-) as the primary product. Pure salts [(dpma)AlCl2](+)[Cl](-) and [(dpma)AlCl2](+)[AlCl4](-) could be obtained by performing the reactions in CH3CN. In the case of InCl3, a neutral monoadduct (dpma)InCl3 formed regardless of the stoichiometry emplo…
Triterpene saponins from the roots of Bupleurum spinosum Gouan
2020
Abstract Three previously undescribed triterpene saponins, and four known ones, were isolated from the EtOH/H2O extract of the roots of Bupleurum spinosum. Their structures were characterized using spectroscopic techniques including 1D and 2D NMR (1H, 13C, COSY, TOCSY, ROESY, HSQC, and HMBC) experiments and mass spectrometry as 3-O-β-D-glucopyranosyl-(1→6)-[β-D-glucopyranosyl-(1→2)]-[α-L-rhamnopyranosyl-(1→4)]-β-D-glucopyranosyl-3β,16β,23,28-tetrahydroxyolean-12-ene, 3-O-β-D-glucopyranosyl-(1→6)-[β-D-glucopyranosyl-(1→2)]-[α-L-rhamnopyranosyl-(1→4)]-β-D-glucopyranosyl-3β,16β,28-trihydroxy-23-oxoolean-12-ene, 3-O-β-D-glucopyranosyl-(1→6)-[α-L-rhamnopyranosyl(1→4)]-β-D-glucopyranosyl-3β,16β,2…
Studies on coordination compounds vii, chromatographic, thermoanalytical and spectroscopic studies on thermal decomposition of cadmium(II) and lead(I…
1982
On the basis of decomposition temperatures and infrared spectra, cadmium(II) and lead(II) bissalicylaldoximates were considered to havetrans andcis structures, respectively.
Surface initiated molecularly imprinted polymer films: a new approach in chiral capillary electrochromatography
2001
A new generation of imprinted composite particles was tested as capillary electrochromatography stationary phase. Silica particles characterised by a well defined particle size (10 µm diameter), shape and pore system (1000 A) were modified with an azoinitiator and subsequently used to graft molecularly imprinted polymers targeted to bind L-phenylalanine anilide. Fused silica capillaries were packed over a length corresponding to 8 cm, using a pneumatic amplification pump, and the stationary phase thus obtained was tested with respect to its electrochromatographic performance. The electroendosmotic flow mobility was evaluated with respect to both the different content of polymer on the silic…
High performance PA6/CNTs nanohybrid fibers prepared in the melt
2012
Commercial and home-made carbon nanotubes (CNTs) were plasma treated under oxygen atmosphere and then added to polyamide 6 (PA6) in order to prepare fibres by melt spinning. For comparison, pristine nanofillers were used too. The effect of functionalization and of filler characteristics on the morphological, rheological, mechanical and electrical properties of the fibres was studied by TEM and SEM, rheological measurements, tensile and electrical conductivity tests. The results demonstrated that the functionalization led to a better mechanical performance and the morphological analysis confirmed that the adhesion, the dispersion and the alignment of the nanotubes within the polymer matrix w…
Interaction of a Recombinant Prion Protein with Organo-Mineral Complexes as Assessed by FT-IR and CPMAS 13C NMR Analysis
2010
Prion proteins are considered as the main agents for the Transmissible Spongiform Encephalopathies (TSE). The misfolded form, PrP Sc , which is also indicated as the etiological agent for TSE, exhibits high resistance to degradation in environmental processes. Soil contamination by prion proteins is a real environmental issue since contaminated soils can become potential reservoir and diffuser for TSE infectivity. In this work, the interaction of prion protein with organo- mineral complexes was studied by using a recombinant non pathogenic prion protein and a model soil system. This latter was represented by a soil manganese mineral coated with polymerized catechol. FT-IR spectra showed ami…
From ceria nanotubes to nanowires through electrogeneration of base
2009
The preparation of Ce(OH)3/CeO2 nanostructures (NSs) through electrogeneration of base into anodic alumina membranes was studied. The effects of solvent (alcohol and/or water), Ce3? partner anion nature (chloride or nitrate) and concentration, applied potential or current density in driving the morphology toward nanowires (NWs) and/or nanotubes (NTs) was described. The structural analysis performed by X-Ray Diffraction and Raman Spectroscopy allowed to evidence that the presence of Ce(IV) into the nanostructures strongly depends on the oxygen content in the growing environment.