Kinetic study of formation/dissociation of Cu(II) and Zn(II) complexes of cyclen macrocyclic ligand with pendant thiol group

Outubro 2013

The kinetic properties of macrocyclic ligand 2-[1,4,7,10–tetraazacyclododecane-1-yl]-ethanethiol (L1, DOSH) were studied with Cu(II) and Zn(II) metal ions, using conventional molecular absorption spectroscopy in pH regions 2.5–4.7 and 4.3–6.0 for Cu(II) and Zn(II), respectively. The obtained partial rate constants, measured at 25 °C and ionic strength I = 0.1 M (KCl), are slightly lower than for parent cyclen (1,4,7,10-tetraazacyclododecane) macrocyclic ligand supporting the hypothesis that the thiol pendant arm is not directly involved in the formation of these metal complexes. The study of the dissociation of the copper(II)-L1 complex in the presence of perchloric acid and at higher temperatures (75–95 °C) showed that this complex is more kinetically inert than the copper(II) complex with cyclen, indicating that the presence of the thiol pendant arm plays a key role as protecting group of copper(II) ion. On contrary, the dissociation of zinc(II) complex in presence of copper(II) ion measured at laboratory temperature (25 °C) and in 0.1 M-solution of hydrochloric acid is going via the metal-exchange reaction mechanism. Altogether, these findings show that L1 ligand presents favorable kinetic properties for further conjugation with biomolecules, aiming at their use in medicinal chemistry.

Autores da comunidade :

• 

  M

  Maria Paula Cordeiro Crespo Cabral Campello Aboim de Barros

  ist25375

  Afiliações e fontes

  IST > C2TN

  Centro de Ciências e Tecnologias Nucleares

  De: orcid

  ID: 10910725

  De: cienciavitae

  ID: 2877166

• 

  I

  Isabel da Graça Rego dos Santos

  ist25348

AO - Versão original do autor

Elsevier

https://www.sciencedirect.com/journal/polyhedron

Polyhedron

268

273

62

0277-5387

10.1016/j.poly.2013.06.052

WOS:000324226200032

chemical-sciences - Química

Palavras-chave

• Macrocyclic ligands
• Cyclen derivatives
• Thiol group
• Copper/zinc complexes
• Formation/dissociation kinetics
• Rate constants
• Radiopharmaceuticals

eng - Inglês

http://dx.doi.org/10.1016/j.poly.2013.06.052