Cu2+ coordination properties of a 2-pyridine heptaamine tripod: characterization and binding mechanism.
The synthesis, protonation, and Cu(2+) coordination chemistry of a tripodal heptaamine ligand (L(1)) functionalized with 2-pyridine fragments at the ends of its three branches are reported. L(1) presents six relatively high protonation constants followed by much more reduced constant that as indicated by the UV-vis and NMR data, occur on the pyridine fragments. p[H]-metric, ESI/MS(+), EPR and UV-vis data show that L(1) is able to form mono-, di-, and trinuclear Cu(2+) complexes. Slippage movements and molecular reorganizations have been observed to occur as a function of p[H] in the 1:1 Cu(2+) complexes. The kinetic studies showed that the complex formation is fast and proceeds through a dissociative Eigen-Wilkins mechanism. The decomposition of CuL(1) upon addition of acid excess occurs with two separate kinetic steps; the rate constant for the fast process does not vary with respect to the H(+) concentration whereas a linear dependence on H(+) is observed for the slow step.
Sornosa Ten
Alejandra
A
Laboratoire de Physico-Chimie Bioinorganique, Institut de Chimie, UMR 7177 CNRS-UdS, Université de Strasbourg, ECPM 25, rue Becquerel, 67200 Strasbourg, France.
Humbert
Nicolas
N
Verdejo
Begoña
B
Llinares
José M
JM
Elhabiri
Mourad
M
Jezierska
Julia
J
Soriano
Conxa
C
Kozlowski
Henryk
H
Albrecht-Gary
Anne-Marie
AM
García-España
Enrique
E
D003300:Copper / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D008024:Ligands; D015394:Molecular Structure; D011073:Polyamines / Q000138:chemical synthesis* / Q000737:chemistry*; D011522:Protons; D011725:Pyridines / Q000737:chemistry*; D021241:Spectrometry, Mass, Electrospray Ionization
D008024:Ligands; D011073:Polyamines; D011522:Protons; D011725:Pyridines; D003300:Copper