KINETIC STUDIES OF COMPLEXATION AND DECOMPLEXATION OF BIS(PHOSPHONIC ACID) CYCLAM DERIVATIVES WITH COPPER(II) ION

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Authors

SVOBODOVÁ Ivona MUDROVÁ Michaela LUBAL Přemysl KOTEK Jan HERMANN Petr HAVEL Josef LUKEŠ Ivan

Year of publication 2004
Type Article in Proceedings
Conference Book of Abstracts of Inorganic Reaction Mechanisms Meeting 2003, January 8-10, 2004, Athens, Greece
MU Faculty or unit

Faculty of Science

Citation
Field Analytic chemistry
Keywords BIS(PHOSPHONIC ACID) CYCLAM DERIVATIVES; copper(II) complexes; thermodynamics; kinetics
Description Complexes of Cu(II) with macrocyclic ligands are utilized as bifunctional chelating agents in nuclear medicine, e.g. in radioisotope diagnostics (64Cu) or in tumor radiotherapy (67Cu). There is necessity to know thermodynamic and kinetic properties (formation and dissociation rate constants) of copper and other biometal ion complexes under experimental conditions similar to body fluids for possible medical application in vivo. In this work, the formation kinetics of copper(II) complexes of macrocyclic ligands with phosphonic acid pendant arms was studied (dipon, L1, Me2dipon, L2, dipon-diester, L3) (t = 25 oC, I = 0.1 M). The reactivity decreases in order L1 > L2 > L3. The copper(II) complex of L1 ligand can be found in two isomeric forms. They differ in the number of bound donor atoms and cyclam skeleton arrangement. The mechanism of isomerisation reaction was studied in different media (aqueous ammonia, water) by means of different experimental techniques and catalysis of reaction by ammonia was observed. The dissociation kinetics of copper(II) complexes of L1 and L2 macrocyclic ligands was investigated under extreme experimental conditions (t = 25-65 oC, I = 5 M (Na,H)ClO4). The acid-assisted dissociation of complexes is faster for [Cu(H2L2)] than for [Cu(H2L1)] compounds. In case [Cu(H2L1)], both isomeric species demonstrate a high kinetic inertness in presence of 5 M perchloric acid (t = 25 oC, Tau1/2 = 20 min and 6.7 months for penta- and hexacoordinated isomers, respectively).
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