Schiff base tailed silatranes for the fabrication of functionalized silica based magnetic nano-cores possessing active sites for the adsorption of copper ions

Abstract

One pot fabrication of functionalized magnetite nanoparticles using Schiff base tethered silatranes as modifiers is reported. In this work a new Schiff base functionalized silane and the corresponding silatrane were synthesized by the condensation of 2-hydroxy-4-methoxybenzophenone with 3-aminopropyltriethoxysilane and -silatrane, respectively. The latter was purified by convenient recrystallization. Thus, the silatrane, which was characterized by elemental analysis, spectroscopic techniques and single crystal X-ray diffraction, was used as a modifier to functionalize magnetite nano-cores to introduce active lone-pair donor systems on their surface. The Schiff base functionalized magnetite nano-particles were characterized by Powder X-Ray Diffraction (XRD), Fourier Transform Infrared Spectroscopy (FT-IR), Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM) and Vibrating Sample Magnetometry (VSM). These studies revealed superparamagnetic nanoparticles of polydispersed spherical shape. Although functionalization of the nano-cores introduces some organic moieties onto the surface, some properties of the nano-particles have not been altered significantly, i.e. their magnetic nature, spherical shape and XRD patterns were retained even after the modification. Moreover, Langmuir adsorption isotherm measurement revealed that the Schiff base functionalized nanoparticles possess better adsorption capacity for copper ions (0.207 mmol g⁻¹) as compared to magnetite nanocores coated with silica (0.141 mmol g⁻¹). The Schiff base functionalized magnetic nanomaterial can be used for the adsorption of copper ions without interferences because the adsorption remained unaffected in the presence of other metal ions up to certain limits.