E. P. Turevskaya

Abstract: This review covers the works on the sol-gel preparation of oxides from metal alkoxides that were carried out at the Faculty of Chemistry, Moscow State University, and at the Karpov Research Institute of Physical Chemistry. The composition and properties of the oxide powders and films prepared were considered in relation to the nature of alkoxides and solvents and complex formation in solution. The morphology and phase composition of the powders were examined in relation to hydrolysis conditions. Electrical and optical data are presented for titanate, zirconate, niobate, and tantalate powders, ceramics, and films

Abstract: The X-ray single-crystal studies of [M{Ti2(OR)9}2](M = Ca, Ba; R = Et) obtained from EtOH solutions in 1 : 4 metal–titanium ratios show that these complexes, both in the solid state and in solution, are composed of symmetric molecules, in which the central eight-coordinated metal atom is bound to two face-sharing bioctahedral [Ti2(OR)9] groups.

Abstract: This review covers the works on the sol-gel preparation of oxides from metal alkoxides that were carried out at the Faculty of Chemistry, Moscow State University, and at the Karpov Research Institute of Physical Chemistry. The composition and properties of the oxide powders and films prepared were considered in relation to the nature of alkoxides and solvents and complex formation in solution. The morphology and phase composition of the powders were examined in relation to hydrolysis conditions. Electrical and optical data are presented for titanate, zirconate, niobate, and tantalate powders, ceramics, and films

Abstract: Metal alkoxides containing more than one sort of metallic element are predominantly known in the field of heterobimetallic derivatives. In order to pass to heterotrimetallic homoleptic alkoxides bimetallic alkoxides have to be prepared which are at the same time heterobimetallic and heteroleptic. They serve as starting materials in salt elimination reactions leading to heterotrimetallic homoleptic alkoxides. The structural entity serving as a building block in these reactions must be kinetically stable in order to survive in the synthetic procedures. Besides heterotermetallic alkoxides, heterobimetallic alkoxides with halides and cyclopentadienyl as ancillary ligands and transition metal complexes of new mixed-metal alkoxy derivatives are presented. Besides the syntheses and the structural characterization reactivity, spectral aspects in view of dynamic or static structures and applications of hetero(bi- and tri-)metallic alkoxides are discussed.

Abstract: Metal-doped polyoxotitanium cages (M-POTs) of the type [TixOy(OR)zMnXm] (M = a main group, transition metal or lanthanide; X = an anion such as a halide) can be regarded as molecular fragments of metal-doped TiO2. As such M-POTs can be used as structural models for the inclusion of metal ions into the TiO2 lattice and the ways in which well-defined microstructural changes affect photo-induced hole–electron separation. They are also potential organically-soluble redox-catalysts for a range of organic transformations and have been shown to be useful single-source precursors for the deposition of metal-doped TiO2. The applications of M-POTs as molecular precursors to metal-doped TiO2 offers a high degree of atomic control in the low temperature fabrication of photocatalytic thin films, which have applications in pollution control and water splitting. This perspective highlights the structural trends in M-POTs, their electronic behaviour and their applications as single-source precursors, looking at current and future trends in the development of inorganic precursors for device applications.

Abstract: Investigation of the solvent and alkoxide precursor effect on the nonhydrolytic sol-gel synthesis of oxide nanoparticles by means of an ether elimination (Bradley) reaction indicates that the best crystallinity of the resulting oxide particles is achieved on application of aprotic ketone solvents, such as acetophenone, and of smallest possible alkoxide groups. The size of the produced primary particles is always about 5 nm caused by intrinsic mechanisms of their formation. The produced particles, possessing the composition of natural highly insoluble minerals, are biocompatible. Optical characteristics of the perovskite complex oxide nanoparticles can easily be controlled through doping with rare earth cations; for example, by Eu(3+). They can be targeted through surface modification by anchoring the directing biomolecules through a phosphate or phosphonate moiety. Testing of the distribution of Eu-doped BaTiO(3) particles, modified with ethylphosphonic acid, demonstrates their facile uptake by the plants with active fluid transport, resulting finally in their enhanced concentration within the cell membranes.