Layered hybrid nickel phyllosilicates and reactivity of the gallery space

Aminated phyllosilicates have been synthesized by a sol-gel process from re actions of nickel ions and three analogous trialkoxysilanes, 3-(trimethoxys ilyl)propylamine, N'-[3-(trimethoxysilyl)propyl]ethylenediamine and N'-[3-( trimethoxysilyl)propyl]diethylenetriamine, in aqueous basic medium at 298 a nd 323 K. The inorganic-organic hybrids SILNix (x = 1-3) were denoted follo wing the above sequence of aminated silanes, varying from one to three amin o groups on the organosilanes. The amount of nickel in the SILNix matrices showed the presence of cations in two different environments: (i) octahedra l sites and (ii) in the gallery space complexed by amino groups. The therma l stability decreased in the order SILNi1 > SILNi2 approximate to SILNi3. T he 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 SILNi 2*, respectively. The increased values observed from n = 1 to 3 can be attr ibuted to the presence of organic chains in these new structures, which was confirmed by elemental analysis. The samples showed a peak at 2 theta = 60 degrees (d = 0.16 nm) indexed to the 060 reflection, characteristic of tri octahedral phyllosilicates. XRD results and IR spectroscopy suggested nicke l hydroxide was not obtained. Reactions of the hybrids with 2-pyridine-carb aldehyde were carried out to evaluate the reactivity of the amino groups in the gallery space.