POLYALCOHOLS AND POLYAMINOPOLYALCOHOLS AS SELECTIVE RECEPTORS FOR METAL-IONS

The metal binding properties of polyalcohols and polyaminopolyalcohols are reviewed. A short overview of the early work, which dates back to the end of the 18th century, is given. In addition some significant r esults of the latest developments are presented. Their implications in biology and materials science are illustrated and the main properties of the polyalcohols as metal binding agents are discussed: (i) The in teraction between a polyol and a metal cation is weak while the cation is bound to the neutral hydroxy groups; however, as soon as the coord ination proceeds under deprotonation conditions, polyols become powerf ul ligands. (ii) A high number of hydroxy groups facilitates the forma tion of a variety of different structures, leading to complex equilibr ia where several species coexist. (iii) A deprotonated hydroxy group h as a high tendency to bind more than one metal ion and the formation o f polynuclear species is therefore often observed. The coordination ch emistry of the polyamino-polyalcohols is even more complex, since the amino groups can either act as additional donors for metal binding or serve as internal bases, facilitating the deprotonation and coordinati on of the hydroxy groups. A variety of structural features are present ed and a general scheme of the reactivity pathways of such species in aqueous solutions is discussed.