RESUMO
The synthesis and characterization of Hno1pa2py, a new tacn-based ligand, is reported. The complexation process with Cu(2+) was proved to be very fast even in acidic medium. Potentiometric titrations allowed us to establish that Hno1pa2py exhibits an overall low basicity as well as a high selectivity for Cu(2+) over Zn(2+) cations. The copper(II) complex was synthesized and characterized using UV-vis and EPR spectroscopies and density functional theory (DFT) calculations. The studies clearly showed that the [Cu(no1pa2py)](+) complex is present in solution as a mixture of two isomers in which the ligand is coordinated to the metal center using a N5O donor set with the metal center in a distorted octahedral geometry. The very high kinetic inertness of the [Cu(no1pa2py)](+) complex was demonstrated by using acid-assisted dissociation assays as well as cyclic voltammetry. Preliminary investigations of (64)Cu complexation were performed to validate the potential use of such chelating agent for further application in nuclear medicine. The X-ray crystal structures of copper(II) complexes of L1, the ester derivative of Hno1pa2py, have been determined.
Assuntos
Compostos Aza/química , Complexos de Coordenação/química , Cobre/química , Ácidos Picolínicos/química , Piperidinas/química , Compostos Aza/síntese química , Complexos de Coordenação/síntese química , Cristalografia por Raios X , Espectroscopia de Ressonância de Spin Eletrônica , Ligantes , Modelos Moleculares , Ácidos Picolínicos/síntese química , Piperidinas/síntese química , Espectrofotometria UltravioletaRESUMO
A potent lanthanide chelate, fulfilling the requirements for the development of MRI contrast agents or luminescent probes, was armed with alkyne groups. We then implemented a click methodology to graft the bifunctional ligand to azide-containing glucoside and maltoside scaffolds. The resulting hydrophilic glycoconjugates retained the ligand binding capacity for Eu(3+) or Tb(3+) ion as evidenced by the number of bound water molecules to the lanthanide ion. Divalent Eu(3+) and Tb(3+) complexes were shown to double the brightness of the emitted fluorescent signal compared to its monovalent derivatives. Designing multivalent lanthanide luminescent probes would enable the fluorescent signal of labeled biomolecules to be enhanced.