Novel anion receptors: hybrid materials based on quaternary ammonium salts for selective extraction of dichromate ions

Novel hybrid materials were obtained by modification of three (poly)amine-appended mesoporous silica gels. For all matrices of different side chain lengths, the process proceeded with excellent modification rates. The free analogues of these hybrid materials, podand-type receptors, were also prepared employing a very similar procedure. The organosilicas synthesized were characterized by NMR, infrared spectroscopy, and semi-empirical methods. Their anion exchange properties were conveniently investigated using precise, but also time and cost-efficient titration experiments, and the products were found to be powerful complexing agents for dichromate ions.