Group 6 tetracarbonyl complexes of N-[(2-pyridyl)methyliden]-α (or β)-aminonaphthalene: Spectral characterization,electrochemistry, solvatochromism and photophysical studies

A new series of group 6 carbonyl complexes of N-[(2-pyridyl)methyliden]-α (or β)-aminonaphthalene (α/β-NaiPy) are described in this work. The complexes are formulated as cis-[M(CO)₄(α/β-NaiPy)] by elemental, mass and other spectroscopic data. The complexes show emission spectra at room temperature and their quantum yield lies between 0.4 and 0.5. All the complexes exhibit negative solvatochromism. Cyclic voltammetry shows metal centred oxidation and ligand reductions.     

Experimental and theoretical study of vibrational spectra and structure of dihalogermylene and dihalostannylene complexes with 1,4-dioxane and triphenylphosphine

Vibrational (Raman and IR) spectra of the 1:1 complexes of dihalogermylene and dihalostannylene with 1,4-dioxane and PPh₃ have been reported, the structures of the complexes Cl₂Ge·C₄H₈O₂ and Cl₂Ge·PPh₃ updated using high-resolution X-ray method. Quantum-chemistry calculations of the geometry and normal mode frequencies and eigenvectors were carried out for some of the complexes. The results show that in the structure of the polymeric solid complexes of X₂M with 1,4-dioxane, intermolecular coordination XM plays a prominent role, whereas the corresponding complexes with PPh₃ are monomeric. In the vibrational spectra of all the complexes, an inversion of symmetric and antisymmetric stretching νXM (X=Cl, Br; M=Ge, Sn) frequencies, found for ‘free’ X₂M^II particles, still persists, suggesting that the X₂M moieties preserve their specifity as carbene analogues also in the complexes.     

Stability study and quantitative determination of mebeverine hydrochloride in tablets by means of reversed-phase high-performance liquid chromatography

Summary A rapid and specific reversed-phase high-performance liquid chromatographic method (RPHPLC) is described for the determination of mebeverine hydrochloride in tablets. Elution was performed on an octyl silane column with a methanol-water mixture (75-25), containing 0.05% hexylamine as silanol-blocking agent, adjusted to pH 5.0 with phosphoric acid. The method gave accurate, precise and reproducible results. The mean recovery of the drug from six synthetic tablet mixtures was 100.0% with a relative standard deviation (RSD) of 0.94%. In order to test the specificity of the method, the interference of the degradation compounds of mebeverine hydrochloride and of the intermediates from the synthesis was investigated. None of them did interfere. By means of mass spectrometry and UV-spectrophotometry, the degradation compounds of mebeverine were identified as veratric acid and as 4-|ethyl-[2-(4-methoxyphenyl)-1-methylethyl]amino| 1-butanol. The stability study proved that mebeverine hydrochloride is very stable in tablets; the tablets still contain more than 95% of the declared drug potency after storage for more than one year at 50°C.Colofac; Duspatal; Duspatalin     

Spectrum analysis of U-doped LaBr3 single crystals. Part 1: crystal-field analysis

Single crystals of U³⁺:LaBr₃ were grown by the Bridgman-Stockbarger technique. High-resolution polarized absorption spectra of the crystals were recorded at 4.2 K in the 4000-50,000 cm⁻¹ range. Sixty-four experimental crystal-field energy levels of the U³⁺ ion were fitted to a semiempirical Hamiltonian employing free-ion, one-electron crystal-field as well as two-particle correlation crystal-field (CCF) operators with an r.m.s. deviation of 28 cm⁻¹. The performed analysis of the spectra enabled the determination of crystal-field parameters and assignment of the observed 5f³→5f³ transitions. The effects of selected CCF operators on the splitting of some specific U³⁺ multiplets have been investigated and the obtained values of Hamiltonian parameters are discussed and compared with those reported in previous analyses.     

Na3Fe(C2O4)3·5H2O的热解过程和FAB-MS断裂规律

以红外光谱法为主要手段，原位“跟踪”测定铁（Ⅲ）与乙二酸形成的配合物Ｎａ３Ｆｅ（Ｃ２Ｏ４）３．５Ｈ２Ｏ的热解过程，分析了气、固相热解产物。并以色谱分析、差热－热重分析和Ｘ－射线粉末衍射法定性、定量地验证其结果。测定了该配合物快原子轰击质谱，提出了断裂规律。铁的二元羧酸配合物的质谱尚属首见。     

Synthesis and Characterization of Lead Sulfide Nanoparticles in Zirconia-Silica-Urethane Thin Films Prepared by the Sol-Gel Process

PbS nanocrystals (NCs) ranging between 4–8 nm were incorporated into Zirconium-Silica-Urethane (ZSUR) matrix obtained by the sol-gel method. The sizes of the particles were controlled by temperature treatment and by concentration of PbS in ZSUR matrix. The sizes of PbS NCs were determined by TEM measurements. The quantum size effect could also be extracted from optical absorption and photoluminescence spectra. The new matrix allows incorporation of up to 40% PbS forming a characteristic structure of dendrite by reacting lead acetate with ammonium thiocyanate in sol-gel matrix. The sol precursors of the matrix for Zirconium-Silica-Urethane contained zirconium oxide (ZrO₂) matrix solution, tetramethoxysilane (TMOS), 3-glycid oxypropyl trimethoxysilane (GLYMO) and polyethylene urethane silane (PEUS) synthesized separately. The ZrO₂ matrix solution was obtained from zirconium n-tetrapropoxide in propanol and acetic acid was used as a chelating agent to stabilize the zirconium oxide precursor.     

Chiroptical detection during liquid chromatography,part 5: On-line measurement of circular dichroism spectra Δε(λ) during stops of chromatographic flow

Summary A procedure is described which serves to measure circular dichrograms () on line during stops of flow in liquid chromatography. Since the concentration of substrate in the spectrometer cell during the stop is not known, the differential absorption coefficients are calculated from the experimental differential absorbances A by means of UV absorption (i. e. photomultiplier voltage) data. Verifications of the procedure are obtained by its application to three substrates (Table 1), the () spectra of which were known. The present on-line technique is compared with a corresponding off-line method.The N,N-dimethylthiobenzamides1 and2 as well as the 9,10-phenanthrenequinone7 consist of interconvertible enantiomers because their planar states are destabilized by steric overcrowding of groups. The unknown dichrograms () of1, 2 and7 are obtained (Figs. 2 and 4) and discussed with reference to the helicities of these molecules.In memory of the late Professor Dr. Dr. h. c. Günther Snatzke.     

Synthesis and characteristics of the mass spectra of 2,5-dimercapto-2,5-dimethyltetrahydrothiophene

2,5-Dimercapto-2,5-dimethyltetrahyrothiophene was synthesized by the reaction of 1-iodopropan-2-one with hydrogen sulfide in an ether solution of hydrogen chloride at-70°C. Its structure was established by mass spectrometry, ¹H and ¹³C NMR spectroscopy. __________ Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 2, 216–219, February, 2007.