Affiliation:
1. Centro Interdisciplinar de Química e Bioloxía (CICA) and Departamento de Química Universidade da Coruña Campus da Zapateira-Rúa da Fraga 10 15001 A Coruña Spain
2. Department of Chemistry Simon Fraser University 8888 University Drive V5A 1S6 Burnaby British Columbia Canada
3. Life Sciences Division TRIUMF 4004 Wesbrook Mall V6T 2A3 Vancouver British Columbia Canada
4. Departamento de Química Inorgánica Facultad de Ciencias Universidade de Vigo As Lagoas, Marcosende 36310 Pontevedra Spain
Abstract
AbstractWe present a detailed investigation on the coordination chemistry of [nat/203Pb]Pb(II) with chelators H4PYTA and H4CHX‐PYTA. These chelators belong to the family of ligands derived from the 18‐membered macrocyclic backbone PYAN and present varying degrees of rigidity due to the presence of either ethyl or cyclohexyl spacers. A complete study of the stable Pb(II) complexes is carried out via NMR, X‐Ray crystallography, stability constant determination and computational studies. While these studies indicated that Pb(II) complexation is achieved, and the thermodynamic stability of the resulting complexes is very high, a certain degree of fluxionality does exist in both cases. Nevertheless, radiolabeling studies were carried out using SPECT (single photon emission computed tomography) compatible isotope lead‐203 (203Pb, t1/2=51.9 h), and while both chelators complex the radioisotope, the incorporation of carboxylate pendant arms appears to be detrimental towards the stability of the complexes when compared to the previously described amide analogues. Additionally, incorporation of a cyclohexyl spacer does not improve the kinetic inertness of the system.
Funder
Ministerio de Ciencia e Innovación
Xunta de Galicia
Natural Sciences and Engineering Research Council of Canada