Preparation and Characterization of Iron 1,10-Phenanthroline Complex Encapsulated in Silica Sol-Gel Derived Thin Films

Abstract

Transparent sol-gel thin films immobilized with 1,10-phenanthroline were made via the acid catalyzed sol-gel reaction of tetraethoxysilane (TEOS) in presence of 1,10-phenanthroline. Different surfactants that include cationic cetyltrimethyl ammonium bromide (CTAB), anionic sodium dodecyl sulfate (SDS) and nonionic Triton X-100 (TX-100) were tested for the improvement of the host material mesostructure, increasing its porosity and well accommodation of the 1,10-phenanthroline within the silica matrix. The immobilized phen thin films show similar behavior in presence of SDS surfactant as their free counterpart in aqueous solution without any shift in the wavelength of UV absorption spectra. The immobilized 1,10-phenanthroline complex retained its activity toward Fe2+ metal ions by immobilization and produced a stable complex without any shift in the wavelength of Vis absorption spectra comparing with its free counterpart. Different parameters include concentrations of 1,10-phenanthroline, Fe2+ and surfactant, type of surfactant, life time and number of measurements were investigated. The 1,10-phenanthroline thin films sensor showed sensitivity, stability, repeatability, reproducibility and long life time behavior. Maximum stability of 1,10-phenanthroline thin films were achieved by drying at 80oC, whereas the range of the temperature of the Fe2+ metal ion aqueous solutions at 25 - 40 oC. The quantitative measurements of iron using the prepared 1,10-phenanthroleine thin films validation of procedure was (~ 5%) comparing with the standard method. Accordingly this solid state thin films can be used as sensors for iron detection in versatile aqueous samples with different environmental matrices.