RT journal article
T1 Copper(II) complexes of quinoline polyazamacrocyclic scorpiand-type ligands: X-ray, equilibrium and kinetic studies
A1 Castillo González, Carmen Esther
A1 Máñez Muñoz, María Ángeles
A1 García Basallote, Manuel
A1 Clares, M. Paz
A1 García España, Enrique
A1 Blasco, Salvador
A2 Ciencia de los Materiales e Ingeniería Metalúrgica y Química Inorgánica
AB The formation of Cu(II) complexes with two isomeric quinoline-containing scorpiand-type ligands has been studied. The ligands have a tetraazapyridinophane core appended with an ethylamino tail including 2-quinoline (L1) or 4-quinoline (L2) functionalities. Potentiometric studies indicate the formation of stable CuL2+ species with both ligands, the L1 complex being 3–4 log units more stable than the L2 complex. The crystal structure of [Cu(L1)](ClO4)2·H2O shows that the coordination geometry around the Cu2+ ions is distorted octahedral with significant axial elongation; the four Cu–N distances in the equatorial plane vary from 1.976 to 2.183 Å, while the axial distances are of 2.276 and 2.309 Å. The lower stability of the CuL22+ complex and its capability of forming protonated and hydroxo complexessuggest a penta-dentate coordination of the ligand, in agreement with the type of substitution at the quinoline ring. Kinetic studies on complex formation can be interpreted by considering that initial coordination of L1 and L2 takes place through the nitrogen atom in the quinoline ring. This is followed by coordination of the remaining nitrogen atoms, in a process that is faster in the L1 complex probably because substitution at the quinoline ring facilitates the reorganization. Kinetic studies on complex decomposition provide clear evidence on the occurrence of the molecular motion typical of scorpiands in the case of the L2 complex, for which decomposition starts with a very fast process (sub-millisecond timescale) that involves a shift in the absorption band from 643 to 690 nm.
PB The Royal Society of Chemistry and Owner Societies
YR 2012
FD 2012
LK http://hdl.handle.net/10498/20507
UL http://hdl.handle.net/10498/20507
LA eng
DS Repositorio Institucional de la Universidad de Cádiz
RD 11-nov-2026