COMPARATIVE FORMATION-CONSTANTS FOR METAL-IONS WITH MACROCYCLES BASEDON 1,4,8,11-TETRAAZACYCLOTETRADECANE AND CARRYING DIAMINE, DICARBOXYLATE OR AMINE-CARBOXYLATE PENDANTS
Y. Baran et al., COMPARATIVE FORMATION-CONSTANTS FOR METAL-IONS WITH MACROCYCLES BASEDON 1,4,8,11-TETRAAZACYCLOTETRADECANE AND CARRYING DIAMINE, DICARBOXYLATE OR AMINE-CARBOXYLATE PENDANTS, Polyhedron, 16(4), 1997, pp. 599-602
Acid dissociation constants for the newly isolated dihydrogen 4,8,11-t
etraazacyclotetradecane-6,13-dicarboxylate (diacmac), as well as for h
ydrogen 11-tetraazacyclotetradecane-6-amine-13-carboxylate (acammac) a
nd hyl-1,4,8,11-tetraazacyclotetradecane-6,13-diamine (diammac) are re
ported. The ligands differ somewhat in their selection of metal ions,
which is reflected in the formation constants for complexation (log K-
ML, 25 degrees C) which have been determined for the d(10) metal ions
Zn2+ (diammac, 14.9; acammac, 14.7; diacmac, 26.3), Cd2+ (diammac, 10.
6; acammac, 16.7; diacmac, 15.9), Hg2+ (diammac, 10.5; acammac, 17.3;
diacmac, 21.8) and Pb2+ (diammac, 10.8; acammac, 10.7; diacmac, 19.0);
and the d(5) Mn2+ ion (diammac, 6.2; acammac, 12.0; diacmac, 18.3). D
ifferences arise in part from the increasing availability of potential
O donors versus N donors in stepping from diammac to diacmac, and imp
ly a clear role for the pendants in binding metal ions. Copyright (C)
1996 Elsevier Science Ltd