Layered hybrid nickel phyllosilicates and reactivity of the gallery space

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.

Silylation of clay mineral surfaces

“…On the other hand, in situ silylation technology was widely used in the synthesis of inorganic-organic hybrid phyllosilicates, such as 2:1 trioctahedral minerals (e.g., talc, hectorite and saponite) (Carrado, 2000;da Fonseca et al, 2000b;Fujii et al, 2003;Jaber et al, 2003;Silva et al, 2002), 2:1 dioctahedral minerals (e.g., pyrophyllite, beidellite and montmorillonite) (Jaber et al, 2005;Miehe-Brendle et al, 2010), and 1:1 minerals (e.g., kaolinite) (da Fonseca and Airoldi, 2000). The structure of inorganic-organic hybrid phyllosilicate strongly depended on the used metallic cations and organosilanes as silicon source in a sol-gel process.…”

“…The structure of inorganic-organic hybrid phyllosilicate strongly depended on the used metallic cations and organosilanes as silicon source in a sol-gel process. When divalent cations were used, the obtained hybrid phyllosilicates were trioctahedral minerals, whereas dioctahedral minerals was gained when trivalent cations were used (Burch, 1984;Carrado et al, 2001;da Fonseca et al, 2000b;Fujii et al, 2003;Jaber et al, 2005;Miehe-Brendle et al, 2010). The organosilanes with three hydrolysable functional groups (e.g., ethoxy group and methoxy group) were employed to build Si\O tetrahedral sheet, in which each silicon atom at the center of a tetrahedron was linked to the organic chain by a Si\C covalent bond.…”

A relevante potencialidade dos centros básicos nitrogenados disponíveis em polímeros inorgânicos e biopolímeros na remoção catiônica

“…A maioria dessa classe de compostos lamelares organossilicatos possui o magnésio ocupando os sítios octaédricos, seguido pelo níquel 66,69-78 , com estruturas cristalinas lamelares 2:1, porém outros filossilicatos organofuncionalizados contêm alumínio 69,79,80 , cobre 76 , zinco 81 e cálcio 82 no interior da estrutura inorgânica. Os filossilicatos sintetizados dos cátions magnésio, níquel, cobre e zinco contendo na estrutura lamelar nas cadeias pendentes as funções amino, tiol ou macrociclos são matrizes úteis para remoção de cátions de solução aquosa na interface sólido/líquido 68,70,[75][76][77]81 . O primeiro exemplo envolvendo a reação do agente sililante derivado do glicidóxido para formar o filossilicato de níquel com um macrociclo foi usado para as constantes de equilíbrio para alguns metais da primeira série de transição 68 e foram determinados com ênfase nos dados termodinâmicos da interação cátion/centro básico nitrogenados, via calorimetria 58,70,77 .…”

Water Soluble Iron aminoclay for Catalytic Reduction of Nitrophenol

“…Though the chemical modification of the inorganic phyllosilicate frame-works was the aim of several studies, majority of these hybrids has magnesium located inside the lamellar octahedral sites; it could be substituted by nickel, 4 calcium 5 and copper. 6 These clay lamellae can be used to immobilize single biomolecules and proteins such as DNA, Hb, Mb, GOx and these found to exhibit enhanced stability and regenerate without loss of its activity.…”