Renato Rosseto

Hydrous non-crystalline phosphates: structure, function and a new white pigment

Hydrated non-crystalline inorganic solids are often neglected due to the limited comprehension of their complex physico-chemical and structural properties. However, these non-crystalline materials exhibit a rich and varied chemistry, interesting for scientific and technological reasons. This work reviews general aspects of formation of hydrated non-crystalline solids, with special emphasis on aluminum (poly)phosphate materials. Precursors and concentration variations, temperature, ageing and reaction pH are trivial synthetic variables, but they promote the formation of a myriad of compounds adequate for many functions. Amorphous aluminum phosphates are widely employed in different industrial applications, providing good examples of the potential of hydrous amorphous solids.

Indústria química: evolução recente, problemas e oportunidades

Chemical industry underwent a significant upturn in the past few years. In Brazil, the position of this industry has been continuously strengthened as the second largest industrial sector. Current circumstances are discussed, especially the need for increased innovation, the impacts of nanotechnology, biotechnology and information technologies. Some misconceptions on the Brazilian chemical industry are criticized and recent improvements are described, including those related to environmental protection, to conclude that its prospects are very good, considering both the availability of basic raw materials (oil, natural gas, agribusiness products and minerals), the growing demand and increased competitiveness.

A plasticidade dos amorfos: fazendo pigmentos brancos com fosfato de alumínio

A new white pigment made out of nano-structured non-crystalline aluminum phosphate was recently launched as an industrial product. Pigment opacifying properties are not intrinsic to aluminum phosphate but they arise as the result of a rare hollow particle nano-structure. This is in turn derived from the core-and-shell structure of amorphous aluminum phosphate precipitated under well-defined conditions. The new pigment is a product of the often neglected chemistry of non-crystalline ionic solids that can probably be a rich source of new successful products. The text describes a short account of the R&D activities, from the initial ideas to the present.

Modeling of Alkynes: Synthesis and Theoretical Properties

In this paper we present the synthesis and simulation of alkynes derivatives. Semiempirical calculations were carried out for the ground and first excited states, including the spectroscopic properties of the absorption and emission (fluorescence and phosphorescence) spectra by INDO/S-CI and DNdM-INDO/S-CI methods with geometries fully optimized by PM3/CI. The fact that the theoretical spectra are in accord with the experimental absorption spectra gives us a new possible approach on how structure modifications could affect the non-linear optical properties of alkynes.

Electronic interactions in [Ru3(mu3-R² CCC6H4-4-R¹)(mu -dppm)(mu-CO) (CO)7] (R¹ = NO2 and R² = Fc; R¹ = NO2, CN and R² = Ph)

The co-ordination of FcCCC6H4-4-NO2 (1) to a ruthenium carbonyl cluster to yield [Ru3(m 3-FcCCC6H4-4-NO2) (m-dppm)( m-CO)(CO)7] (2) is reported. The cyclic voltammograms of these compounds and of the analogous clusters [Ru3(m3 -h2-C6 H5CCC6H4-4-R)(m -dppm)(m -CO)(CO)7] (R= H, 3; CN, 4; NO2, 5) allowed an evaluation of the electronic communications between the different redox sites (ferrocenyl and -NO2 groups, and Ru3 moiety) and an analysis of the relative electron donor-acceptor capabilities of each of the three redox centres that compose 2. Furthermore, the inertness of 2, compared with clusters 3-5 which loose CO readily was attributed to the interaction between the ferrocenyl group and the metallic frame.