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Effect of Mixed Pendant Groups on the Solution Properties of 12‐Membered Azapyridinomacrocycles: Evaluation of the Protonation Constants and the Stability Constants of the Europium( III ) Complexes
Author(s) -
Siaugue JeanMichel,
FavreRéguillon Alain,
Dioury Fabienne,
Plancque Gabriel,
Foos Jacques,
Madic Charles,
Moulin Christophe,
Guy Alain
Publication year - 2003
Publication title -
european journal of inorganic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.667
H-Index - 136
eISSN - 1099-0682
pISSN - 1434-1948
DOI - 10.1002/ejic.200300016
Subject(s) - chemistry , europium , protonation , propionate , potentiometric titration , luminescence , stability constants of complexes , ligand (biochemistry) , chemical stability , crystallography , molecule , medicinal chemistry , stereochemistry , inorganic chemistry , organic chemistry , aqueous solution , ion , receptor , materials science , biochemistry , optoelectronics , electrode
The protonation constants (log K i H ) of new N ‐acetate or N ‐propionate substituted azamacrocycles derived from 12‐membered pyridinoazamacrocycles were determined by potentiometric methods. The number of coordinated water molecules, determined from the luminescence lifetime of the Eu III complexes, indicates a decreasing degree of hydration upon increasing the ring size of the pendant arms. Each ligand forms a 1:1 complex with Eu III , for which the stability constants (log K therm ) have been measured by time‐resolved laser‐induced europium luminescence. The replacement of acetate pendant groups by propionate increases the overall basicity of 12‐membered pyridinoazamacrocycles but decreases the stability constant of the Eu III complexes from log K = 21.1 with three N ‐acetate pendant arms to log K = 13.7 with two N ‐propionate and one N ‐acetate pendant arms and to log K = 10.7 with three N ‐propionate pendant arms. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)