Transition Metal Complexes Supported on Natural Zeolitic Materials: An Overview

The literature concerning transition metal complexes supported on natural zeolitic materials is reviewed and the relevant experimental methods, along with the characterisation techniques, are presented. In contrast to synthetic zeolites, the research already performed using naturally occurring species is not extensive and mainly refers to HEU-type zeolites, as well as, to natural analogues of explicit synthetic products (FAU-type zeolites). Different intrazeolite and surface complexes of several metals (Mn, Fe, Co, Ni, Cu and Ag) have been investigated and potential applications of the obtained composite materials have been proposed. The utilisation of these materials in environmental technology has particularly been pointed out (e.g. specific sorbents/ catalysts, environment-friendly pesticides/insecticides, innovative pharmaceuticals/ nutrients). The future perspectives of this subject could include the investigation of supported complexes of Pt-group elements, and the study of specific complexes of transition metals with increased biological interest (e.g. Fe, Mn). The latter will also contribute to the understanding of problems related to the geochemistry and biogeochemistry of the microporous tectosilicate minerals.