ESR study of ordered Ti(III) clusters in frozen solutions

The ESR spectrum of exchange-coupled Ti³⁺ ions of gg_e has been observed in dissolution products of metallic titanium in HCl, evidencing the formation of chloride clusters of mutually ordered Ti³⁺ ions in d_z2-ground state in distorted tetrahedral coordination. The cooperative Jahn-Teller effect (CJTE) defines orbital ordering of the d¹ of Ti³⁺ ions in the cluster.     

Luminescence of the pyrene/N,N-diethylaniline triplet exciplex in methanol at room temperature

Fluorescence, whose spectral and magnetic properties permit its assignment to the luminescence of a triplex exciplex, has been discovered at times 3 sec after photoexcitation in the luminescence spectrum of the pyrene+N,N-diethylaniline system in methanol at 600 nm by the method of nanosecond stroboscopic fluorometry.Translated from Teoreticheskaya i Eksperimental'naya Khimiya, Vol. 25, No. 5, pp. 623–626, September–October, 1989.     

Environmental effects on hydrogen bonded systems: A quantum chemical study of proton relay model systems

In this paper an application of a reaction field theory of solvent effects has been made to study proton transfer mechanisms in hydrogen bonded systems coupled to an environment. The latter is simulated with reaction fields having variable strength and direction (defined with respect to the supermolecule's total dipole moment direction), together with superposed uniform external electric fields. Changes in proton potential curves and some other properties of a model water dimer and a water trimer are reported. The results are discussed in relation to relevant phenomena in biology and biochemistry, namely proton relay systems in enzymatic catalysis.     

Untersuchungen über die Biosynthese der Cyclite, 17. Mitt.: Bildung vond-bornesit und Dambonit inNerium oleander

Zusammenfassung Dambonit (1,3-Di-O-methyl-myo-inosit) entsteht inNerium oleander, wie durch Einbauversuche mit radioaktiv markiertemmyo-Inosit undd-Bornesit sowie durch Bestimmung der Zeitabhängigkeit der Bildung der Cyclite bei Assimilation von¹⁴CO₂ nachgewiesen wurde, ausmyo-Inosit überd-Bornesit als Zwischenprodukt. Neben Dambonit finden sich in der Cyclitfraktion vonN. oleander auchd-Bornesit,myo-Inosit sowiel-Leucanthemit.myo-Inosit unterliegt in der Pflanze-besonders im Winter-einem sehr intensiven Stoffwechsel, der zu nichtzyklischen Verbindungen führt.

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InNerium oleander dambonitol (1,3-Di-O-methyl-myo-inositol) is formed frommyo-inositol withd-bornesitol as intermediate, as could be shown with the help of incorporation experiments with radioactively labelledmyo-inositol andd-bornesitol and also by the determination of the time dependence of the formation of the cyclitols from¹⁴CO₂ in photoassimilation experiments. Besides dambonitol the cyclitol fraction ofN. oleander contains alsod-bornesitol,myo-inositol andl-leucanthemitol. Especially in wintermyo-inositol undergoes a very active catabolism in the plant which leads to the formation of non-cyclic compounds.

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H. Kindl undO. Hoffmann-Ostenhof, Mh. Chem.97, 1771 (1966).     

Electrochromic properties of WO<Subscript>3</Subscript> and WO<Subscript>3</Subscript>:P thin films

WO₃ and WO₃:P (5 mol% H₃PO₄) thin films were prepared using the sol-gel route and the electrochromic properties of the films were investigated using in situ spectroelectrochemical methods. The measurements were performed in propylene carbonate solution with 0.1 M LiClO₄ as electrolyte. During the cathodic polarization at –0.8 V a blue coloration is observed with a reversible variation between 14% and 84% of the transmittance at λ=633 nm. The kinetics for the bleaching process is faster for the WO₃:P film than for the undoped WO₃ film. Electronic Publication     

Sorption of Hexacyanoferrate(II,III) Anions on Nickel(II) Hydroxide

Fe(CN)₆ ^{3 -} and Fe(CN)₆ ^{4 -} anions are sorbed from aqueous solutions of their potassium and cesium salts on -Ni(OH)2 by the mechanism of anion exchange with hydroxy groups. Alkali metal cations (K⁺, Cs⁺) are also partly sorbed on nickel(II) hydroxide in the form of anionic complexes (K,Cs) _z Fe(CN)₆ ^{(n - z)-}, where n = 3 or 4 (0 < z < n). The chemical composition of the new phase appearing in contact of nickel(II) hydroxide with aqueous potassium and cesium hexacyanoferrates(II, III) was determined by X-ray phase analysis and IR spectroscopy.     

N,N,N′-Trialkyl-1,8-diaminonaphthalenes: convenient method of preparation from protonated proton sponges and the first X-ray information

A simple procedure for the synthesis of N,N,N′-trialkyl-1,8-diaminonaphthalenes is described. It consists in partial demethylation (dealkylation) of commercially available proton sponge [1,8-bis(dimethylamino)naphthalene] and some of its derivatives at heating with HBr-KI-DMF system. Limitation, scope and a possible mechanistic pathway for the reaction are discussed. For isomeric 8-dimethylamino-1-methylamino- and 1-dimethylamino-8-methylamino-4-nitronaphthalenes, X-ray measurements have been conducted. The first examples of complete realkylation reactions in the naphthalene proton sponges are reported.     

The interaction between TEOS and some polyols

Hybrid organic-inorganic materials, silica – polyols (ethylene-glycol – EG; 1,2 propane diol – 1,2PG; 1,3 propane diol – 1,3PG and glycerol – GL), were prepared by a sol-gel process starting from tetraethylorthosilicate (TEOS) and polyols, in acid catalysis. The resulting materials were studied by thermal analysis (in air and nitrogen), FTIR and solid state ²⁹Si-NMR spectroscopy. These techniques evidenced the presence of polyols in the silica matrix both hydrogen bounded and chemically bounded in the silica network. The thermal analysis proves to be the most appropriate technique to evidence the organic chains linked in the matrix network and to follow the thermal evolution of the gels to the SiO₂ matrix.     

Estimation of the size of liposomes by modified HDC

Internal calibration in modified hydrodynamic chromatography has been realized by the approach of Prieve and Hoysan, i.e. the use of polystyrene monodisperse latexes to evaluate the equivalent capillary radius, R. The value obtained has been used to estimate the average sizes of a variety of liposome samples from egg yolk lecithin.