EPR and Optical Absorption Studies of VO2+ Doped Trisodium Citrate Dihydrate Single Crystals
The electron paramagnetic resonance of VO2+ doped trisodium citrate dihydrate (Na3C6H5O7·2H2O) single crystals and powder has been examined at room temperature. The angular variation of the EPR spectra has shown that two different VO2+ complexes are located in different chemical environments, each environment containing two magnetically inequivalent VO2+ sites in distinct orientations occupying substitutional positions in the lattice and showing a very large angular dependence. The crystalline field around the VO2+ ion is nearly axial. The optical absorption spectrum shows three bands, centered at 24631, 16892, and 12195 cm−1. The spin Hamiltonian parameters and the molecular orbital coefficients are calculated from the EPR and optical data, and result are discussed. Keywords EPR; Trisodium Citrate; Absorption the Spectrum; Vanadyl Ion
Theoretical studies of the optical spectra and EPR parameters for VO2+ ions in Zn(antipyrine)2(NO3)2
The optical spectrum band positions and EPR parameters (g factors g//, g and hyperfine structure constants A// and A) for VO 2+ ions in Zn(antipyrine)2(NO3)2 are theoretically studied from the complete diagonalization (of energy matrix) method (CDM) and the perturbation theory method (PTM). In the two methods, the contributions from the spin–orbit (SO) coupling of central 3d n ion and ligand are taken into account. The theoretical results from both methods are not only consistent with the experimental values, but also close to each other. The results are discussed.
Stereoselective disposition of ibuprofen enantiomers in infants.
The pharmacokinetics of the enantiomers of ibuprofen were investigated after oral administration of a single 7.6 +/- 0.3 mg kg-1 dose of the racemate in 11 infants. Mean (+/- s.d.) half-lives were 1.6 +/- 0.5 h for S(+) and 1.5 +/- 0.5 h for R(-) and mean (+/- s.d.) AUC values were 31.5 +/- 14.3 mg l-1 h for S(+) and 36.6 +/- 13.8 mg l-1 h for R(-). Since plasma concentrations of the active S(+)-isomer were lower than those reported in adults, a higher dosage might be required in infants.