New layered inorganic–organic nanocomposites containing n-propylmercapto copper phyllosilicates

Abstract

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−1 of organic groups, with larger thermal stability for the magnesium compound and surface areas of 46.9 ± 1.8 and 107.0 ± 3.0 m2 g−1 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 confirmed by infrared data, showing a stretching band at 2556 cm−1 for the magnesium hybrid, while this same band was absent in copper phyllosilicate. 29Si 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 first species demonstrated that better polymerization occurred in the SILMgSH hybrid. The amount of copper adsorbed on the magnesium phyllosilicate was 5.93 mmol g−1. 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.