Glass-ceramics are prepared by controlled separation of crystal phases in glasses, leading to uniform and dense grain structures. On the other hand, chemical leaching of soluble crystal phases yields porous glass-ceramics with important applications. Here, glass/ceramic interfaces of niobo-, vanado- and titano-phosphate glasses were studied by micro-Raman spectroscopy, whose spatial resolution revealed the multiphase structures. Phase-separation mechanisms were also determined by this technique, revealing that interface composition remained unchanged as the crystallization front advanced for niobo- and vanadophosphate glasses (interface-controlled crystallization). For titanophosphate glasses, phase composition changed continuously with time up to the equilibrium composition, indicating a spinodal-type phase separation.

Fundamental aspects of the conception and applications of ecomaterials, in particular porous materials in the perspective of green chemistry are discussed in this paper. General recommendations for description and classification of porous materials are reviewed briefly. By way of illustration, some case studies of materials design and applications in pollution detection and remediation are described. It is shown here how different materials developed by our groups, such as porous glasses, ecomaterials from biomass and anionic clays were programmed to perform specific functions. A discussion of the present and future of ecomaterials in green chemistry is presented along with important key goals.

Neste trabalho o vidro poroso Vycor foi utilizado como matriz para a imobilização de complexos contendo ligação metal-metal [Pd2Cl2(dppm)2], [Pd2(SnCl3)Cl(dppm)2 ] e [Pd2(SnCl3)2(dppm)2] A elevada reatividade das ligações metal-metal em reações de inserção de moléculas como CO e SO2 é preservada no meio poroso, sendo reversível sob vácuo. Os espectros de RMN MAS 31P, refletância difusa no infravermelho e Raman indicaram que há uma gama de interações possíveis entre o vidro e as moléculas, como resultado da disponibilidade de diferentes grupamentos presentes nas moléculas, bem como de uma topologia porosa irregular. O caráter estático das moléculas no ambiente restrito impede movimentos do anel Pd2P4C2 entre as conformações barco e cadeira, de modo que as moléculas confinadas podem ter diferentes conformações.

Porous Vycor glass (PVG) is used as a matrix for immobilization of complexes containing metal-metal bonds: [Pd2Cl2(dppm)2], [Pd2(SnCl3)Cl(dppm)2 ] and [Pd2(SnCl3)2(dppm)2]. The high reactivity of the metal-metal bonds in insertion reactions with small molecules such as CO and SO2 is preserved in the pore medium, and is reversible under vacuum. 31P MAS-NMR and Raman spectra indicate that there is a range of interactions between the glass and the adsorbed molecules as a result of the availability of different groups in the molecules and of the irregular pore topology as well. The static character of the molecules in the restrictive pore environment precludes motions such as flipping of the ring Pd2P4C2 between boat and chair conformations and rotation of the phenyl rings, and the molecules may present a range of conformations.