Determination of δ13 CV−PDB and δ15NAIR values of cocaine from a big seizure in Germany by stable isotope ratio mass spectrometry†

In this study, δ¹³C_{V? PDB} and δ¹⁵N_AIR values of 132 cocaine samples from a big seizure in Germany in 2002 were determined using elemental analyser isotope ratio mass spectrometry. The 1.2 tons of cocaine were packed in 1 kg packages and the cocaine bricks inside these packages showed certain logos. Twenty different logos could be identified. Results show a large variability among some samples, for δ¹⁵N_AIR values ranging from?17 to ?2 ‰. Furthermore, the possibility of linking samples with the same logo was checked. The results show that, in general, there is no relationship between the determined isotope ratio and a certain logo.     

Superposition-model analysis of rare-earth doped BaY 2 F 8

The energy level schemes of four rare-earth dopants (Ce 3+ , Nd 3+ , Dy 3+ , and Er 3+ ) in BaY 2 F 8 , as determined by optical absorption spectra, were fitted with a single-ion Hamiltonian and analysed within Newman's Superposition Model for the crystal field. A unified picture for the four dopants was obtained, by assuming a distortion of the F m ligand cage around the RE site; within the framework of the Superposition Model, this distortion is found to have a marked anisotropic behaviour for heavy rare earths, while it turns into an isotropic expansion of the nearest-neighbours polyhedron for light rare earths. It is also inferred that the substituting ion may occupy an off-center position with respect to the original Y 3+ site in the crystal.     

The assignment of Co-C bond stretching vibrational frequency of CH3Co(DH)2H2O in IR and Raman spectra

Abstract

In order to aid assignment of Co-C bond stretching vibrational frequency of CH₃Co(DH)₂H₂O (DH=dimethylgIyoximato monanion) in IR and Raman spectra, its isotopic substitution CD₃Co(DH)₂H₂O has been synthesized and normal coordinate analyses on the two complex have been made. The bands were assigned in terms of potential energy distribution. The results provide definitive band assignment of the Co-C bond and Co-N bond stretching modes which are coupling at 511 cm^?1.     

NMR Studies of Drugs. Applications of Achiral and Chiral Wthanide Shift Reagents to Bupropion

Abstract

The ¹H NMR spectra of racemic samples of the antidepressant drug, bupropion, 1, have been studied in CDCl₃ solution at 60 and 200 MHz with the achiral lanthanide shift reagent (LSR), tris(6,6,7,7,8,8,8-heptafluoro-2,2-dimethyl-3,5-octanedionato)europium (III), 2, and the chiral reagent, tris[3-(heptafluoropropylhydroxymethylene)-d-camphorato]europium(III), 3. Both LSR produced substantial lanthanide induced shifts consistent with ¹H assignments, but the bound complexes of 1 with 2 versus 3 may not be isostructural. With 3, substantial enantiomeric shift differences were observed for the t-butyl, CH ₃CH, NCH, and the aryl H-2 and H-6 signals, which should permit potential direct determination of enantiomeric excess.     

NMR Studies of Drugs: Antipyrine and Analogs. I. Use of Achiral and Chiral Lanthanide Shift Reagents to Examine Hindered Rotation.

The 200 MHz ¹H NMR spectra of the analgesic, antipyrine, 1, have been studied in CDC1₃ solution at ambient temperatures with the achiral lanthanide shift reagent (LSR) tris (6, 6, 7, 7, 8, 8, 8-heptafluoro-2, 2-dimethyl-3, 5-octanedionato) europium (III), Eu(FOD)₃, 2, and with the chiral LSR, tris[3-(heptafluoropropylhydroxymethylene)-(+)-camphorato]europium(III), Eu(HFC)₃, 3., Lanthanide-induced shift (LIS) magnitudes and broadening of selected signals are consistent with predominant LSR binding at the carbonyl oxygen with either 2 or 3. Of the different possible conformational regimes for the N-phenyl group of 1, our results appear to rule out a slow exchange limit (SEL) system with the N-phenyl coplanar with the heterocyclic ring. Perpendicular rings in an SEL regime can not be ruled out. A rapidly-rotating N-phenyl (fast exchange limit, FEL system) would also be consistent with observed results. Accurate chemical shifts for the aryl protons (overlapped in the 200 MHz spectrum of unshifted 1) are determined from spectra with added LSR by extrapolation to zero molar ratios of [LSR]:[1]. Relative slopes in the plots of chemical shift versus [LSR]:[1] molar ratios are calculated for each proton signal of 1.     

NMR Studies Of Drugs. Chiral Solvating Agents for Direct Determination of Enantiomeric Excess of the Cardiac Antiarrhythmic,Mexiletine

The 400 MHz ¹H NMR spectra of the cardiac antiarrhythmic, mexiletine, 1, have been studied with different chiral solvating agents (CSA) to obtain a very promising method for direct determination of enantiomeric excess (e.e.) with limited amounts of 1. The methods included the use of β-cyclodextrin (β-CD), γ-cyclodextrin (γ-CD), α-methoxy-α-(trifluoromethyl)phenylacetic acid (MTPA), and 2,2,2-trifluoro-1-(9-anthryl)ethanol (TFAE). Use of TFAE in CDCl₃ with the free base of 1 appeared to give the best results, with enantiomeric shift differences observed for the signals of the sidechain methyl, CH ₃CH, and the aryl methyls.     

Kinematical and Dynamical Inelastic Light Scattering in Conducting Crystals

Fundamentals of the kinematical quantum theory of inelastic light scattering from electronic excitations in conducting crystals are reviewed. Keeping both the →Δ and →p·→A terms in the photon-electron interaction the general expression for the differential scattering cross-section is obtained. Emphasizing opacity effects and anisotropies arising from the Doppler shift the scattering kinematics is analyzed. The scattering from free-carrier density fluctuations is considered briefly. The basic concepts of a recently established phenomenological theory of dynamical light diffraction in opaque crystals are discussed, and some aspects of a predicted phonon induced anomalous transmission of light below the plasma edge in semiconductors are studied.     

NMR Studies in the Heterocyclic Series. XXIII. - 13C Spectra of Indazole and 3-Azido-Indazole in Acidified Dimethylsulfoxid Solutions

We reported previously the ¹³C NMR spectra of indazole 1 ² and 3-azido-indazole 2 ³.     

Infrared Study of the Interaction of Tetramethylthiourea and Dimethylthioformamide with Phenol Derivatives

Abstract

The hydrogen bonded complexes between hydroxylic bonds and oxygen or nitrogen bases have been extensively studied by infrared spectrometry. However, meager experimental results are available for sulfur participation in hydrogen bond formation. There seems little doubt that in thioamides - hydroxylic complexes, the donor site for hydrogen bonding is sulfur, particularly in view of the blue shift of the n → π? transition of the thiocarbonyl group in proton donor solvents ¹. This paper reports on a study of the equilibrium constants (K) and on the frequency shifts of the 1 v _OH stretching vibration of hydrogen bonded complexes between tetramethylthiourea (TMTU) or dimethyltnioformamide (DMTF) and some phenol derivatives.     

The Vibrational Spectra and Normal Coordinate Analysis of Semiconducting Y2BaCuO5

Both infrared (FTIR) and Raman spectra have been measured for the green semiconducting Y₂BaCuO₅ (2:1:1) in the Y-Ba-Cu-O system. Factor group analysis and normal-coordinate-analysis calculations have been conducted for this phase in order to determine the symmetries, the wavenumber locations and the eigenvector nature of its first-order modes of vibration along with the appropriate set of modified GVF force constants. The predicted vibrational spectral results are in good agreement with the experimentally observed FTIR and Raman spectral data. The generated force constants are interpreted along with those for related phases on the basis of structure.