Design of New Water Receptors Based on Oligomeric Complexes of Copper(II) and Nickel(II)

The interaction of mono- and oligomacromolecular complexes of copper(II) and nickel(II) with water vapor has been studied on a piezoquartz microbalance. It has been established that the effectiveness of adsorption is determined by the nature of the metal ion to a larger extent than the quantity of macrocyclic ligand in the receptor molecule. Oligomacrocyclic complexes of copper(II) are shown to have prospects for use as active coverings of moisture meters working over a wide range of relative humidity.     

Sorption of traces of strontium ions on silica gel containing crown ether

This paper is concerned with the synthesis of silica gel sorbents by the sol method. A sorbent selective for trace amounts of Sr ions has been prepared. This method of synthesis is shown to be preferable to the tradition of impregnating the carrier.L. V. Pisarzhevskii Institute of Physical Chemistry, Ukrainian Academy of Sciences, Ukraine, 252039 Kiev, Science Prosp., 31. Translated from Teoreticheskiya i Éksperimental'naya Khimii, Vol.32, No. 4, pp. 258–260, July–August, 1996. Original article submitted October 17, 1995.     

Long-range spin–spin interactions in the 13C-n.m.r. spectra of the nickel(II) complex of the Schiff base of (S)-N-benzylproline (2-benzoylphenyl)amide and glycine. Quantum-chemical calculations and possible donation of electron density from the π-system of the benzyl group to nickel

Long-range [ ⁿ J(¹³C, ¹³C), ⁿ J(¹⁵N, ¹⁵N) and ⁿ J(¹⁵N, ¹³C)] interactions in the ¹³C-n.m.r. spectra of CDCl₃ solutions of selectively labeled nickel(II) complexes of the Schiff base derived from (S)-N-benzylproline (2-benzoylphenyl)amide and glycine provide experimental evidence for the necessity of the donation of electron density from the -system of the benzyl ring to the nickel orbitals. No such interactions were observed in (²H)DMSO solutions, where the complex exists in a different conformation.     

Photocatalytic hydrogen evolution over mesoporous TiO2/metal nanocomposites

Na⁺ complex with the dibenzo-18-crown-6 ester was used as a template to synthesize mesoporous titanium dioxide with the specific surface area 130–140 m²/g, pore diameter 5–9 nm and anatase content 70–90%. The mesoporous TiO₂ samples prepared were found to have photocatalytic activity in Cu^II, Ni^II and Ag^I reduction by aliphatic alcohols. The resulting metal–semiconductor nanostructures have remarkable photocatalytic activity in hydrogen evolution from water–alcohol mixtures, their efficiency being 50–60% greater than that of the metal-containing nano-composites based on TiO₂ Degussa P25.The effects of the thermal treatment of mesoporous TiO₂ upon its photocatalytic activity in hydrogen production were studied. The anatase content and pore size were found to be the basic parameters determining the photoreaction rate. The growth of the quantum yield of hydrogen evolution from TiO₂/Ag⁰ to TiO₂/Ni⁰ to TiO₂/Cu⁰ was interpreted in terms of differences in the electronic interaction between metal nanoparticles and the semiconductor surface. It was found that there is an optimal metal concentration range where the quantum yield of hydrogen production is maximal. A decrease in the photoreaction rate at further increment in the metal content was supposed to be connected with the enlargement of metal nanoparticles and deterioration of the intimate electron interaction between the components of the metal–semiconductor nanocomposites.     

Mesoporous TiO2 microspheres with improved efficiency for photooxidation of volatile organic compounds

Research on Chemical Intermediates - Mesoporous hierarchical TiO2 microspheres have been prepared using titanium alkoxide and crown ether as a structure-directing agent in combination with a small...     

Photocatalytic activity of a mesoporous TiO<Subscript>2</Subscript>/Ni composite in the generation of hydrogen from aqueous ethanol systems

TiO₂/Ni metal-semiconductor composites were prepared from mesoporous titanium dioxide obtained by sol-gel precipitation in the presence of a structure-forming template. The photocatalytic activity of mesoporous TiO₂/Ni composites in the generation of hydrogen from aqueous ethanol mixtures was discovered and studied in detail.__________Translated from Teoreticheskaya i Éksperimentalnaya Khimiya, Vol. 41, No. 1, pp. 24–29, January–February, 2005.     

Effects of template synthesis conditions on TiO2 gel structuring

Studies have been made on the effects of template synthesis conditions (initial substances, SA/TiO₂ ratio, and pH) on TiO₂ gel formation; under certain conditions, a nanoperiodic structure is formed in the presence of a cationic surfactant SA (ethonium, cetyltrimethylammonium chloride) and in the presence of anionic SA (sodium dodecylsulfat, and dodecylbenzenesulfonic acid). A feature of the TiO₂ gels made in the presence of a crown ether (dibenzo-18-crown-6) is that it contains a nanoperiodic structure and a crystalline one (anatase). L. V. Pisarzhevskii Institute of Physical Chemistry, National Academy of Sciences of Ukraine, 31 Prospekt Nauki, Kiev 03039, Ukraine. Translated from Teoreticheskaya i éksperimental'naya Khimiya, Vol. 36, No. 4, pp. 251–256, July–August, 2000.     

Heterophase Reactions of Hydrazine Vapor with Copper(I) π-Complexes at the Surface of a Piezoelectric Quartz Crystal

Quartz Crystal Microbalance (QCM) was used to study heterophase reactions of hydrazine vapor with solid copper(I) -complexes Cu₂Cl₂ · DVB, CuCl · AA, (HDAA)CuCl₂, and Cu(HMA) · H₂O (where DVB is CH₂=CH-C₆H₄-CH=CH₂, AA is CH₂=CH-CH₂-NH₂, HDAA is (CH₂=CH-CH₂)₂NH₂ ⁺, and HMA is the HOOC-CH=CH-COO^-. It was found that all the complexes can add hydrazine reversibly. However, in contrast to ionic complexes, molecular complexes gradually decomposed while reacting with the vapor of N₂H₄. The kinetic parameters such as the rate constants of forward and reverse heterophase reactions were determined. Complex Cu(HMA) · H₂O was found to be most sensitive to the vapor of N₂H₄.