Synthesis of uniform anatase TiO2 nanoparticles by gel–sol method: 4. Shape control

The sol-gel synthesis of metal oxides can be performed via the hydrolysis and condensation of metal cations in aqueous solutions. This inorganic route provides a cheap and reliable way for industrial uses. However, many hydrolyzed precursors can be present simultaneously in the precursor solution and very few data are available on the formation of condensed species. The so-called Partial Charge Model provides a useful guide to describe and predict hydrolysis and condensation reactions in aqueous solutions. A charge-pH diagram can be established. It shows how condensation can be initiated via acid-base or redox reactions. The two basic condensation processes, olation and oxolation, are then discussed in terms of a charge-electronegativity diagram. They can lead either to small solute condensed species (polyanions or polycations) or to the formation of an infinite network (colloids, gels, or precipitates). Complexation by anionic species is finally discussed in the frame of an electronegativity-pH diagram. It also plays an important role during the formation of solid phases.

Aqueous chemistry of metal cations: Hydrolysis, condensation and complexation

Synthesis of uniform anatase TiO2 nanoparticles by gel-sol method: 1. Solution chemistry of Ti(OH)(4-n)+n complexes

Publisher Summary This chapter offers information on homoleptic complexes of 2,2'-bipyridine (bpy). The chapter focuses on the class of complexes that contain only bpy ligands bonded to the metal. The unique metal-binding properties of bpy were recognized from the outset. The third renaissance in bpy chemistry can be traced to the commercial availability of the ligand in the 1950s, when large amounts were required for the preparation of Diquat insecticides. The current interest in complexes of bpy is associated with the extremely interesting electrochemical, photophysical, and photoelectrochemical properties that they exhibit. 2,2'-Bipyridine is a strong field ligand that forms relatively stable complexes, with the inherent M–N bond strength enhanced by the chelate effect. Complexes with main group metal ions, and with lanthanides and actinides, can be prepared in water or organic solvents. The bis complexes are known for a range of metals and oxidation states though they tend to be more common for lower formal oxidation states. The bpy ligand is remarkable for the wide range of formal oxidation states with which it is associated. The chapter discusses the general trends in the reactivity of specific complexes under the appropriate elements. Iron, ruthenium, and osmium have played a crucial role in the development of the chemistry of 2,2'-bipyridine.

Homoleptic Complexes of 2,2′-Bipyridine

This chapter makes a general overview of pillared clay minerals. First, the general concepts of the process and the terminology recommended by the IUPAC are summarized, followed by the analysis of the host clay minerals and of the pillaring species, with special attention to the Al 13 polycation, mixed species, and new species. The main experimental pillaring methods are summarized, and also the main characteristics of the pillared solids, with special attention to the linking between the clay mineral layers and the polycations. Also, an overview of the mathematical modelling of pillaring processes is given. The chapter does not give exhaustive information in each item, available in review articles and books, but the general concepts needed for a general knowledge of the pillaring process and of the pillared solids.

Pillared Clays and Clay Minerals

Hydrolytic precipitation reaction of titanium(IV) from (Na, H)Cl aqueous solution

The hydrolytic precipitation reaction of Mg(II) from aqueous NaNO3 solution

Spectrophotometric study of the reaction of zirconium with Chrome Azurol S and fluoride.

The coordination behavior of aluminum(III) with 8-hydroxy-7-[(2 ' -carboxy-1 ' -phenyl)azo]quinoline-5-sulfonic acid (H3pqs) was examined. This quinolinol derivative functions as a terdentate ligand of the O-N-O type to form mono- and bis-(O-N-O) complexes by way of the reaction of [Al(H2O)6]3+ with Hpqs2- and pqs3- and of [Al(OH)(H2O)5]2+ with H2pqs− and Hpqs2-. The ligand substituion reaction of [Al(pqs)2]3- with 8-quinolinol-5-sulfonic acid was also studied in connection with its reaction mechanism.

Coordination selectivity and ligand substitution reactions of an aluminum(iii) complex with 8-hydroxy-7-[(2 ' -carboxy-1 ' -phenyl)-azo]quinoline-5-sulfonic acid

Hisahiko Einaga

Papers

Hydrolytic precipitation reaction of titanium(IV) from (Na, H)Cl aqueous solution

The hydrolytic precipitation reaction of Mg(II) from aqueous NaNO3 solution

Spectrophotometric study of the reaction of zirconium with Chrome Azurol S and fluoride.

Coordination selectivity and ligand substitution reactions of an aluminum(iii) complex with 8-hydroxy-7-[(2 ' -carboxy-1 ' -phenyl)-azo]quinoline-5-sulfonic acid

Complex formation and precipitation reaction of titanium(IV) from (Na, H)Cl aqueous solution containing phosphate