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.

Abstract---Two analogous inorganic-organic hybrids with a phyllosilicate-like structure SILMgl and SILMg2, containing 3-aminopropyl-and N-propylethylenediaminetrimethoxysilane were synthesized through a sol-gel process. These hybrids adsorbed divalent cations of cobalt, nickel, copper, and zinc from aqueous solution to give the effectiveness of adsorption capacities in the sequence Cu 2 § > Zn 2+ > Ni 2+ > Co 2+. SILMgl has a higher capacity of adsorption than SILMg2. Elemental analysis, X-ray diffractometry, thermal analysis, infrared and nuclear magnetic resonance spectroscopies, and energy dispersive system microscopy characterized all hybrids. The proposed adsorption mechanism involves dissolution of the precursor matrix, formation of a phyllosilicate around the adsorbed ion, and a complexation of the cation by the amino-pendant groups in the interlayer. These new phyllosilicates are more crystalline than the original hybrids. The adsorption of Co z+ increases the interlayer distance to maximum values of 1.81 and 2.24 A for SILMgl and SILMg2, respectively. Thermal analysis data showed a decrease of thermal stability with cation adsorption. Si-O-Si groups were detected by infrared spectroscopy in all hybrids and a band at 1384 cm x was assigned to the nitrate counter anion, which indicates the participation of this ion in the sphere of coordination of the interlayer complexes. The photomicrographs obtained by scanning electron microscopy showed the organized distribution of the sheet structure for these synthesized phyllosilicates.

1.23 : 1 and Of formula Na~6Al8~Silo6038, * 250HzO. The X-Ray analysisThe crystalline structure of the samples was established by X-ray diffraction using a Siemens D-500 diffractometer monitored at 35 kV and 15 mA, with Cu-Ka radiation (A = 0.15406 nm) at a scan speed of 1 degrees min-' (in 28)with Diffrac-AT software [version 3.2, SOCABIM (1993)l with a sample surface area of 6.45 cm2; JCPDS PDF 41-1049 for CdS was used to reference the peaks. PA techniqueThe PA effect looks directly at heat generated in a sample due to non-radiative deexcitation processes following the absorp- Chemical and X-ray diffraction analysisThe parameter q was fixed to values of 0.05, 0.10, 0.20, 0.50 and 0.80. Fig. 3(a) and (b) illustrate the plot of number of Cd 2652

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.