Magnesium and copper phyllosilicates, SILMSH (M~Mg, Cu), were synthesized by a sol±gel process from the reaction of these metallic cations and mercaptotrialkoxysilane in aqueous basic solution at 298 K. The inorganic±organic hybrids formed were characterized by elemental analysis, giving 4.88 and 3.68 mmol g 21 of organic groups, with larger thermal stability for the magnesium compound and surface areas of 46.9¡1.8 and 107.0¡3.0 m 2 g 21 for magnesium and copper hybrids, respectively. X-Ray diffraction patterns gave basal peaks associated with an interlayer distance of 1300 pm for SILMgSH due to the presence of the organic radical chain in the structure. However, for the copper hybrid an interplanar distance of 695 pm was obtained. The terminal S±H groups on organic chains in the structure were con®rmed by infrared data, showing a stretching band at 2556 cm 21 for the magnesium hybrid, while this same band was absent in copper phyllosilicate. 29 Si NMR showed the presence of silicon species: R±Si*±(OSi) 3 , R±Si*±(OSi) 2 ±OH and R±Si*±(OSi)±(OH) 2 in the inorganic±organic backbone structure. The ®rst species demonstrated that better polymerization occurred in the SILMgSH hybrid. The amount of copper adsorbed on the magnesium phyllosilicate was 5.93 mmol g 21. The interaction of this cation in the SILMgSH matrix can be related to two processes: rearrangement of inorganic layers around copper cations and formation of interlayer complexes with S±H groups. The nanocomposite containing adsorbed copper has a similar structure to the SILCuSH hybrid, suggesting a new route for these copper compounds. A simple low-temperature procedure was employed to synthesize these reproducible SILMgSH/Cu and SILCuSH hybrids, which are 1 : 1 phyllosilicates.

Three analogous phyllosilicates were synthesized via a sol−gel process from the reaction of magnesium ions with aminated trialkoxysilanes in an aqueous basic medium at 373 K. The inorganic−organic hybrids obtained, designated as SILMgx (x = 1−3) are related to [3-aminopropyl]-, [N-(2-aminoethyl)-3-aminopropyl]-, and [(10-amino)-4,7-diazanonyl]trimethoxysilane, respectively. The elemental analysis of these hybrids gave the following C/N ratios:  3.1, 2.5, and 2.4. Thermal analysis data showed 50.7, 56.2, and 58.0% weight losses for the same sequence of hybrids. However, the thermal stability decreased in the order SILMg1 > SILMg2 > SILMg3. The surface areas of these matrixes are <2.0 m2 g-1 and X-ray diffraction patterns gave lamellar distances of 1745, 2063, and 2323 pm for SILMgx (x = 1−3). The infrared data indicated the existence of a phyllosilicate structure with absorption at 540 cm-1, which is associated with vibration of the Mg−O group. 29Si NMR showed the presence of three silicon species:  T1, T2, and T3 in the inorganic−organic backbone structure. The photomicrographs obtained by scanning electron microscopy showed in all cases well-formed particles that have irregular shapes and particle sizes.

No abstract

Aminated phyllosilicates have been synthesized by a sol±gel process from reactions of nickel ions and three analogous trialkoxysilanes, 3-(trimethoxysilyl)propylamine, N'-[3-(trimethoxysilyl)propyl]ethylenediamine and N'-[3-(trimethoxysilyl)propyl]diethylenetriamine, in aqueous basic medium at 298 and 323 K. The inorganic± organic hybrids SILNix (x~1±3) were denoted following the above sequence of aminated silanes, varying from one to three amino groups on the organosilanes. The amount of nickel in the SILNix matrices showed the presence of cations in two different environments: (i) octahedral sites and (ii) in the gallery space complexed by amino groups. The thermal stability decreased in the order SILNi1wSILNi2#SILNi3. The basal peaks were associated with lamellar distances of 1.64, 2.15 and 2.45 nm for SILNix (x~1±3), respectively. For the phyllosilicates obtained at room temperature, the values were 1.36 and 1.96 nm for SILNi1* and SILNi2*, respectively. The increased values observed from n~1 to 3 can be attributed to the presence of organic chains in these new structures, which was con®rmed by elemental analysis. The samples showed a peak at 2h~60³ (d~0.16 nm) indexed to the 060 re¯ection, characteristic of trioctahedral phyllosilicates. XRD results and IR spectroscopy suggested nickel hydroxide was not obtained. Reactions of the hybrids with 2-pyridinecarbaldehyde were carried out to evaluate the reactivity of the amino groups in the gallery space.

New layered inorganic-organic magnesium organosilicates were prepared by a singlestep template sol-gel synthesis through the reaction of magnesium ions with a synthetic homologous series of urea-alkoxysilanes with the general formula (CH 3 CH 2 O) 3 Si(CH 2 ) 3 -NHC(O)NH( CH 2 ) n CH 3 , for n ) 2, 4, and 6. The nanocomposites were characterized by elemental analysis, solid-state 29 Si and 13 C nuclear magnetic resonance, X-ray diffraction, and thermogravimetry. The results showed that the hybrid materials exhibit lamellar structures similar to those found in the natural inorganic silicate talc. The influence of the length of the organic group of the urea-alkoxysilane employed in the formation of these layered structures is clearly observed by 29 Si NMR spectroscopy. A high degree of condensation for the hybrid synthesized with urea-alkoxysilane containing the longest alkyl chain was obtained. These materials seem to be promising as sorbents for solid-phase extraction of organic pollutant molecules, when dispersed in water, because of their highly hydrophobic character.