Premium
1,4,7‐Triazacyclononane‐Based Bifunctional Picolinate Ligands for Efficient Copper Complexation
Author(s) -
Guillou Amaury,
Lima Luís M. P.,
Roger Mélissa,
EstebanGómez David,
Delgado Rita,
PlatasIglesias Carlos,
Patinec Véronique,
Tripier Raphaël
Publication year - 2017
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.201700176
Subject(s) - chemistry , electron paramagnetic resonance , potentiometric titration , copper , stability constants of complexes , bifunctional , titration , cyclic voltammetry , inorganic chemistry , ligand (biochemistry) , electrochemistry , paramagnetism , chemical stability , crystallography , ion , organic chemistry , nuclear magnetic resonance , electrode , biochemistry , physics , receptor , quantum mechanics , catalysis
Three 1,4,7‐triazacyclononane‐based (tacn‐based) ligands containing picolyl and picolinate pendant arms (no3py, no2pa1py, and no3pa) were synthesized, and their copper(II) complexation properties were studied to evaluate their potentials as chelators for copper radioisotopes. The thermodynamic stability constants of the complexes were determined by potentiometric titrations. These studies evidenced the formation of mononuclear species for no3py and mono‐ and dinuclear species for no2pa1py and no3pa. The pCu values decreased as the number of carboxypicolyl arms increased. The [Cu(no3py)] 2+ complex presented a very high stability constant (log K CuL = 27.4) and a very high selectivity towards Zn 2+ ions (log K ZnL = 17.25). Vis/NIR (NIR = near‐infrared) absorption and electron paramagnetic resonance (EPR) spectroscopy indicated that the three complexes present distorted octahedral geometries with two paramagnetic species, which were identified as the Δ(δδδ) and Λ(δδδ) isomers [and their corresponding enantiomeric forms Λ(λλλ) and Δ(λλλ)] by DFT calculations. The electrochemical properties were investigated by cyclic voltammetry, which revealed quasireversible behavior for the [Cu(no3py)] 2+ complex but irreversible Cu 2+ /Cu + systems for [Cu(no2pa1py)] and [Cu(no3pa)] – .