RT journal article
T1 Pb2+ Complexes of Small-Cavity Azamacrocyclic Ligands. Thermodynamic and Kinetic Studies
A1 Liberato González, Andrea
A1 Aguinaco Martín, Almudena
A1 Clares, M. Paz
A1 Delgado Pinar, Estefanía
A1 Pitarch-Jarque, Javier
A1 Blasco, Salvador
A1 García Basallote, Manuel
A1 García España, Enrique
A1 Verdejo, Begoña
A2 Ciencia de los Materiales e Ingeniería Metalúrgica y Química Inorgánica
A2 Física de la Materia Condensada
K1 Kinetics
K1 Macrocycle
K1 Pb complexes
AB The synthesis, acid–base behavior and Pb2+ coordination chemistry of the new aza-scorpiand like ligand 5-[2-(N-2-fluorenyl)ethylamino]-2,5,8-triaza[9]-2,6-pyridinophane (L1) have been studied by potentiometry, NMR and spectrofluorimetric titrations, and the results are compared with those obtained for the related compounds L2, lacking of the fluorenyl group, and L3, the macrocycle lacking of pendant arm. The crystal structures obtained for the complexes [PbL1][PbL1Cl](NO3) Cl2·4H2O (1) and [PbL3](ClO4)2 (2) reveal that the metal ion is located over the plane defined by the nitrogen atoms of the macrocyclic core due to its inability to accommodate the large Pb2+ ion in the macrocyclic cavity. For L1, the secondary amino group of the pendant arm is implicated in the coordination of the metal ion, although the stereoactive lone pair of Pb2+ prevents the closed conformation associated to the coordination of metal ions in aza-scorpiand derivatives. The kinetics of the acid-promoted dissociation of the ligand from the Pb2+ complexes with the three ligands has been studied using stopped-flow with simultaneous absorbance and fluorescence detection. The results indicate that in spite of their similarity, the dissociation of the metal ion occurs with very different rates in the three complexes. During the course of the kinetic studies evidence was obtained for the occurrence of a photochemical process that leads to ligand degradation with the unexpected elimination of one CH2CH2 fragment from the macrocyclic core
PB The Royal Society of Chemistry
SN 1477-9234
YR 2017
FD 2017
LK http://hdl.handle.net/10498/39685
UL http://hdl.handle.net/10498/39685
LA eng
DS Repositorio Institucional de la Universidad de Cádiz
RD 11-nov-2026