Quantitation of cation binding by silica gel bound thiamacrocycles and the design of highly selective concentration and purification columns for palladium(II), gold(III), silver(I), and mercury(II)

Abstract

The macrocycles 1,4-dithia-19-crown-6 and 1,4,7,10-tetrathia-18-crown-6 were chemically bonded to silica gel. Binding constants for the interaction of Pd 2+ , Au 3+ , Ag + , and Hg 2+ with the immobilized macrocycles were determined using a strongly complexing anion or NH 3 so the concentration of uncomplexed cation would be low enough to prevent quantitative loading of the column. Binding constants for Cu 2+ , Fe 3+ , and other base metals were at least 10 orders of magnitude less than constants for Pd 2+ , Au 3+ , Ag + , and Hg 2+