[15]aneN4S: synthesis, thermodynamic studies and potential applications in chel...

• Author(s): Torres, N. ; Gonçalves, S. ; Fernandes, A. S. ; Machado, J. F. ; de Brito, M. J. ; Oliveira, N. G. ; Castro, M. ; Costa, J. ; Cabral, M. F.
• Date: 2014
• Persistent ID: http://hdl.handle.net/10437/5619
• Origin: ReCiL - Repositório Científico Lusófona
• Subject(s): MACROCYCLIC COMPOUNDS; THIATETRAAZA; STABILITY CONSTANTS; SPECTROSCOPIC STUDIES; CHELATION THERAPY; MERCURY(II) CHELATOR; COPPER(II) CHELATOR
• Document Type: Article
• Language: English

Description

The purpose of this work was to synthesize and characterize the thiatetraaza macrocycle 1-thia-4,7,10,13-tetraazacyclopentadecane ([15]aneN4S). Its acid-base behaviour was studied by potentiometry at 25 °C and ionic strength 0.10 M in KNO3. The protonation sequence of this ligand was investigated by 1H-NMR titration that also allowed the determination of protonation constants in D2O. Binding studies of [15]aneN4S with Mn2+, Fe2+, Co2+, Ni2+, Cu2+, Zn2+, Cd2+, Hg2+ and Pb2+ metal ions were further performed under the same experimental conditions. The results demonstrated that this compound has a higher selectivity and thermodynamic stability for Hg2+ and Cu2+, followed by Ni2+. The UV-visible-near IR spectroscopies and magnetic moment data for the Co(II) and Ni(II) complexes indicated a tetragonal distorted coordination geometry for both metal centres. The value of magnetic moment and the X-band EPR spectra of the Cu(II) complex are consistent with a distorted square pyramidal geometry.