Specific binding of a biotinylated,metallocarbonyl‐labelled dendrimer to immobilized avidin detected by diffuse‐reflectance infrared Fourier transform spectroscopy

Molecular recognition between avidin covalently immobilized at the surface of acrylic resin beads and a transition metallocarbonyl tracer of the biotin ligand was detected using diffuse reflectance infrared Fourier transform spectroscopy. Copyright © 2004 John Wiley & Sons, Ltd.     

Thermal and photochemical production of chromate(VI) ions from some complexes containing the “CrNO”2+ group

Results are reported for the oxidation of complexes of the type [Cr(CN)_5?x(H₂O)_xNO]^x?3 by molecular oxygen in alkaline medium. In the case of the [Cr(CN)₅NO]^3? complex the reaction proceeded photochemically, whereas in othe cases the thermal oxidation was also observed. The influence of pH, CN^? concentration and energy of radiation was investigated.     

Singular measures in circle dynamics

Critical circle homeomorphisms have an invariant measure totally singular with respect to the Lebesgue measure. We prove that singularities of the invariant measure are of Hölder type. The Hausdorff dimension of the invariant measure is less than 1 but greater than 0.Partially supported by NSF grant #431-3604A     

Kinetics of the Protonation of Macrocyclic Amines in the Presence of Monovalent Cations in Aqueous Solution

Abstract

For macrocyclic bases such as: 1-aza-15-crown-5 (N15C5),1,4,10-trioxa-7,13-diazacyclopentadecan (21), 1,7,10,16-tetraoxa-4,13-diazacyclooctadecan (22) and 1, 4, 7, 13, 16-pentaoxa-10, 19-diazacycloheneicosane (23), the kinetics of deprotonation and protonation reactions in the presence of monovalent cations was studied using the temperature jump technique. For the sake of comparison, the measurements were also performed for 1,4-diazabicyclo[2,2,2]octane (DABCO) base, which does not form complexes with monovalent cations. The monovalent cations affect the temperature dependence of the kinetic parameters of deprotonation. They also affect the activation parameters, which is shown by a distribution of ΔH≠ and ΔS≠ values, but do not influence the value of ΔG≠.     

Magnetic resonance study of nanocrystalline 0.10MnO/0.90ZnO

Magnetic properties of nanosize ZnO powders doped with MnO magnetic dopand have been studied. Sample designated as 0.10MnO/0.90ZnO was characterized by XRD that revealed the presence of ZnO and ZnMnO₃ phases. An average size of magnetic ZnMnO₃ nanocrystallites was 9 nm. Magnetic resonance study has been carried out in the 4-290 K temperature range. The spectrum at each temperature was analyzed in terms of three components. The temperature dependences of resonance field, linewidth and integrated intensity of these components have been determined. Magnetic centers responsible for producing the observed spectra have been proposed.     

Out of shear plane deformations in nematic liquid crystals

The stability of the director field to deformations out of the plane of shear is examined by use of the Taylor expansion method based on catastrophe theory. For simple shear flow of nematics, the coming out of the shear plane is found for suitable surface alignment and not too high twist elastic constant. The role of these parameters is pointed out. Non-flow-aligning nematics are also considered, and results consistent with earlier reports are obtained.     

Thiocarbonyl-imide aus der Umsetzung von 2,2,4,4-Tetramethyl-3-thioxocyclobutanon mit Aryl-aziden

Thiocarbonyl Imides from the Reaction of 2,2,4,4-Tetramethyl-3-thioxocylobutanone and Aryl Azides Reaction of 2,2,4,4-tetramethyl-3-thioxocylobutanone ( 6 ) and 4-methoxyphenyl, phenyl, and 4-nitrophenyl azide ( 7a–c , respectively), at 80°, leads to the 11-aryl-5,10-dithia-11-azadispiro[3.1.3.2]undecane-2,8-diones 8a–c (Scheme 3), respectively, in 67–83% yield. The structure of 8b has been established by X-ray crystallography. The formation of the products may be explained via an intermediate thiocarbonyl imide of type D (Scheme 4), generated by the 1,3-dipolar cycloaddition of the aryl azide with the C? S bond of 6 and elimination of N₂.