A new trend in metal-alkoxide chemistry: the elaboration of monophasic organic-inorganic hybrid materials

Effect of ethanol/TEOS ratios and amount of ammonia on the properties of copper-doped calcium silicate nanoceramics

Calcium magnesium silicate glasses could be suggested for the synthesis of scaffolds for hard tissue regeneration, as they present a high residual glassy phase, high hardness values and hydroxyapatite-forming ability. The use of trace elements in the human body, such as Cu, could improve the biological performance of such glasses, as Cu is known to play a significant role in angiogenesis. Nano-bioceramics are preferable compared to their micro-scale counterparts, because of their increased surface area, which improves both mechanical properties and apatite-forming ability due to the increased nucleation sites provided, their high diffusion rates, reduced sintering time or temperature, and high mechanical properties. The aim of the present work was the evaluation of the effect of different ratios of Ethanol/TEOS and total amount of the inserted ammonia to the particle size, morphology and bioactive, hemolytic and antibacterial behavior of nanoparticles in the quaternary system SiO₂-CaO-MgO-CuO. Different ratios of Ethanol/TEOS and ammonia amount affected the size and morphology of bioactive nanopowders. The optimum materials were synthesized with the highest ethanol/TEOS ratio and ammonia amount as verified by the enhanced apatite-forming ability and antibacterial and non-hemolytic properties.

Synthesis of Zirconium Aryloxide Complexes Containing Pendent Vinyl Groups

The attachment of pendent olefin groups to oxygen-ligated zirconium complexes using olefin-substituted phenols and alcohols and readily accessible zirconium reagents is described. Syntheses of three crystallographically characterizable complexes isolable in 55-90% yield are reported. Eugenol, HOC(6)H(3)(OMe-2)(CH(2)CH=CH(2)-4) (HOAr) reacts with [Zr(O(i)Pr)(4)(HO(i)Pr)](2) in toluene to form [((i)PrO)(2)(ArO)Zr(&mgr;-O(i)Pr)](2), 1. CH(2)=CHCH(2)OH reacts with [Zr(NMe(2))(4)](2) in the presence of 2,6-dimethylphenol to form the mixed ligand salt, {Me(2)NH(2)}{[(2,6-Me(2)C(6)H(3)O)(3)Zr](2)(&mgr;-OCH(2)CH=CH(2))(3)}, 2. The potassium salt derived from eugenol, KOAr, reacts with "Zr(OEt)(4)" in THF to form [K(2)Zr(OAr)(4)(OEt)](2)(O), 3.

Characterization of the surface organization of nanostructured hybrid organic-inorganic materials by time-of-flight secondary ion mass spectrometry

Time-of-flight secondary ion mass spectrometry (TOF-SIMS) has been used to analyse the surface composition of organic-inorganic hybrid solids obtained by a sol-gel process. Gels of type O(1.5)Si-R-SiO(1. 5), obtained from bis-silylated precursors (R'O)(3)-R-Si(OR')(3) (R' = Me, Et and R = (-CH(2))(n)-, n = 1, 2, 6, 10, 12;--CH=CH-; (-CH(2))(3)NH(CH(2))(3)-; 1, 1'-ferrocenyl; (CH(2))(n)-Ph-(CH(2))(n)- with Ph = 1,4-phenylene and n = 0, 1, 2; Ph = 1,3,5-phenyl and n = 0) were analysed. The results were highly dependent on the nature of the organic group. When the organic group was small or 'rigid', the main peaks detected corresponded to SiOH and SiOR' residual groups. Fragment ions from the organic group were poorly detected in this case. When the organic group was larger and more 'flexible', characteristic mass fragment ions were detected at higher relative intensities, indicative of a different organization of the organic units in the solid. TOF-SIMS clearly showed the differences between the xerogels derived from mono- and bis-silylated organic precursors : the organic group is present at the surface of mono-silylated xerogels, whereas for bis-silylated ones, the organization is dependent on the length and the flexibility of the organic units. These TOF-SIMS results are in agreement with other features already reported. Copyright 1999 John Wiley & Sons, Ltd.