Synthesis of new spiropyranes and study of the effect of the nature of substituents on their photochromism and complexation

A series of new hydrazones based on 3,3-dimethyl-7-hydroxy-8-formyl-[2H]-1-benzopyran-2,1-[2]-oxaindane] with the substituents of different nature in the hydrazone moiety was synthesized. A comparative study of photochromism and complexation of the synthesized spiropyrans with a number of metal cations was carried out. Spectral and kinetic differences in photochromism and complexation of these compounds were revealed.     

Influence of Cyclodextrins on the Kinetics of Oxidation of Amino Acids and BSA by Hydrazyl Radicals

The kinetics of oxidation of amino acids (Arg, His, Lys, Phe, Thr and Tyr), a dipeptide (Gly-His), and BSA (bovine serum albumin) by two persistent water soluble free radicals of the hydrazyl type has been studied.The rate decreases in the order Arg>Lys>Tyr>Thr>HisBSAPheGly-His with bothfree radicals. Addition to the reaction mixture of - and -cyclodextrin decreases the oxidation rate, probably due to amino acidencapsulation in the cyclodextrin cavity. -Cyclodextrin protects more efficiently against oxidation than -cyclodextrin.     

The microscopic investigation of structures of moving flux lines by neutron and muon techniques

We have used a variety of microscopic techniques to reveal the structure and motion of flux line arrangements, when the flux lines in low T _c type II superconductors are caused to move by a transport current. Using small-angle neutron scattering by the flux line lattice (FLL), we are able to demonstrate directly the alignment by motion of the nearest-neighbor FLL direction. This tends to be parallel to the direction of flux line motion, as had been suspected from two-dimensional simulations. We also see the destruction of the ordered FLL by plastic flow and the bending of flux lines. Another technique that our collaboration has employed is the direct measurement of flux line motion, using the ultra-high-resolution spectroscopy of the neutron spin-echo technique to observe the energy change of neutrons diffracted by moving flux lines. The muon spin rotation (μSR) technique gives the distribution of values of magnetic field within the FLL. We have recently succeeded in performing μSR measurements while the FLL is moving. Such measurements give complementary information about the local speed and orientation of the FLL motion. We conclude by discussing the possible application of this technique to thin film superconductors.     

Tetranuclear copper(II) complex with the µ<Subscript>4</Subscript>-1,6-hexadicarboxylate linker: crystal structure and magnetic properties

Tetranuclear copper(II) complex [Cu₄L₂(OOC(CH₂)₆COO)] (I) based on bis(azomethine), condensation product of 1-phenyl-3-methyl-4-formylpyrazolone-5 with 1,3-diaminopropanol-2, is synthesized. The structure of its DMSO-adduct (Ia) is determined by X-ray diffraction analysis (CIF file CCDC 1447891). The complexes contain two binuclear fragments bonded by the µ₄-1,6-hexadicarboxylate linker. The magnetic exchange interaction in complex I is antiferromagnetic (2J =–155 cm^–1), whereas that in complex Ia is ferromagnetic (2J = 129 cm^–1), which is due to different conformations of the metallochelate cycles.     

An Analysis of Vibrations and Rotations in the First Hydrogen Sulfide Hexade: the 4ν2 H $$_{2}^{{32}}$$ S Band

Optics and Spectroscopy - The infrared spectrum of the H2S molecule is recorded using a Bruker IFS 125HR Fourier transform spectrometer and studied in the range of 4500–5000 cm–1, in...     

Global Analysis of 24 Rovibrational Bands of the Octad of the 76GeH4 Molecule

Russian Physics Journal - A global fitting method has been developed for spherical top molecules. The octad of the GeH4 molecule comprising 24 interacting states has been investigated. By solving...     

Investigation of the quantitative properties of the quadrupole orthogonal acceleration time-of-flight mass spectrometer with electrospray ionisation using 3,4-methylenedioxymethamphetamine

This paper describes the investigation of the potential of a quadrupole orthogonal acceleration time-of-flight mass spectrometer (Q-TOF) equipped with an atmospheric pressure ionisation interface for quantitative measurements of small molecules separated by reversed phase liquid chromatography. To this end, the detection limits and linear dynamic range in particular were studied in an LC/MS/MS experiment using 3,4-methylenedioxymethamphetamine standards and 3,4-methylenedioxyethylamphetamine for internal standardisation. In a second phase, the experiment was repeated with real biological extracts (whole blood, serum, and vitreous humour). A calibration for 3,4-methylenedioxymethamphetamine and its metabolite 3,4-methylenedioxyamphetamine was prepared in each of these matrices again using 3,4-methylenedioxyethylamphetamine as internal standard. The resulting quantitative data were compared with those obtained by liquid chromatography with fluorescence detection for the same extracts. The Q-TOF results revealed excellent sensitivity and a linear dynamic range of nearly four decades (2-10 000 pg on-column, r(2) = 0.9998, 1/x weighting). Furthermore, all the calibration curves prepared in biological material were superimposable, LC/MS/MS and LC-fluorescence, and the quantitative results for actual samples compared very favourably. It was concluded that the Q-TOF achieves a linear dynamic range for quantitative LC/MS/MS work exceeding that of fluorescence detection and at much better absolute sensitivity. Copyright 1999 John Wiley & Sons, Ltd.