Protonation and complex formation with heavy-metal ions of two tetrafunctional amines and of a new structurally related ion-exchange resin

The basicity and complexing ability towards copper(II) of two new tetrafunctional amines containing four basic aliphatic nitrogens (1) and two aliphatic and two heterocyclic nitrogens (2) have been investigated by potentiometric techniques. The basicity constants of the two compounds are different which indicates that the mechanism of protonation is different for the two amines. The presence of complexes [Cu(HL)], [CuL], [Cu(OH)L] for L = (1) and [Cu(H2L)], [Cu(HL)], [CuL], and [Cu(OH)L] for L = (2) could be detected in aqueous solution. A resin whose repeating unit is structurally related to (2) has been synthesized, and its basicity and stability constants have been compared with those of compound (2).