Scientific activity developed in Group IV of Centro de Química Estrutural (IST): characterization and study of bioactive compounds with potential pharmacological (agents for chelating therapy or radiodiagnosis, inhibitors of zinc-containing and Mo-containing enzymes, anti-oxidants, anti-neurodegenerative drugs) or environmental/analytical applications (solid matrices functionalized with chelating moieties). Ligands are evaluated in terms of acid-base and lipohydrophilic character, chelating capacity towards M2+ (Cu, Ni, Zn), M3+ (Fe, Ga, Al, In), Th4+and Mo6+, namely complex stability, coordination modes, speciation at physiological pH and redox properties of both ligands and complexes.