TY - JOUR
T1 - Synthesis and electrochemistry of mono- and binuclear europium complexes with the macrocyclic ligand 1,4,7,10,14,17,20,23-octaazacyclohexacosane-1,4,7,10,14,17,20,23-octaacetic acid (OHEC)
AU - Böttger, U.
AU - Galin, O.
AU - Schumann, H.
AU - Michman, M.
PY - 1995/3/15
Y1 - 1995/3/15
N2 - Mononuclear and binuclear europium complexes with OHEC have been prepared, where OHEC is 1,4,7,10,14,17,20,23-octaazacyclohexacosane-1,4,1,10,14,17,20,23-octaacetic acid. Electrochemical analysis of these complexes shows that in aqueous solution, Eu(III) binds both at the carboxylic group and at the nitrogen donor atoms. The mononuclear complex (Eu(III)OHEC) undergoes a single-electron reduction to Eu(II); the binuclear complex (Eu(III)2OHEC) shows a two-electron reduction to Eu(II) at more cathodic potentials. The stability constants of Eu(III) are much larger than those of Eu(II) complexes. Electrochemical synthesis of Eu(III) complexes is demonstrated and has considerable advantages over the chemical synthesis. In addition to structural information on the complex in solution, electrochemistry provides analysis of residual uncomplexed ions and of the preconditions for possible synthesis. This is particularly important in cases such as this one, for which NMR is inaccessible.
AB - Mononuclear and binuclear europium complexes with OHEC have been prepared, where OHEC is 1,4,7,10,14,17,20,23-octaazacyclohexacosane-1,4,1,10,14,17,20,23-octaacetic acid. Electrochemical analysis of these complexes shows that in aqueous solution, Eu(III) binds both at the carboxylic group and at the nitrogen donor atoms. The mononuclear complex (Eu(III)OHEC) undergoes a single-electron reduction to Eu(II); the binuclear complex (Eu(III)2OHEC) shows a two-electron reduction to Eu(II) at more cathodic potentials. The stability constants of Eu(III) are much larger than those of Eu(II) complexes. Electrochemical synthesis of Eu(III) complexes is demonstrated and has considerable advantages over the chemical synthesis. In addition to structural information on the complex in solution, electrochemistry provides analysis of residual uncomplexed ions and of the preconditions for possible synthesis. This is particularly important in cases such as this one, for which NMR is inaccessible.
KW - Dinuclear complexes
KW - Electrochemistry
KW - Europium complexes
KW - Macrocyclic ligand complexes
UR - http://www.scopus.com/inward/record.url?scp=0007402522&partnerID=8YFLogxK
U2 - 10.1016/0020-1693(94)04297-9
DO - 10.1016/0020-1693(94)04297-9
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AN - SCOPUS:0007402522
SN - 0020-1693
VL - 231
SP - 29
EP - 34
JO - Inorganica Chimica Acta
JF - Inorganica Chimica Acta
IS - 1-2
ER -