Synthesis, ligand pK(a), and Fe(III) complexation constants for a series of bipodal dihydroxamic acids

M K Nguyen-Van-Duong; V Guillot; L Nicolas; A Gaudemer; L Lowry; I Spasojević; A L Crumbliss

doi:10.1021/ic0103143

Synthesis, ligand pK(a), and Fe(III) complexation constants for a series of bipodal dihydroxamic acids

Inorg Chem. 2001 Nov 5;40(23):5948-53. doi: 10.1021/ic0103143.

Authors

M K Nguyen-Van-Duong¹, V Guillot, L Nicolas, A Gaudemer, L Lowry, I Spasojević, A L Crumbliss

Affiliation

¹ Laboratoire de Chimie Bioorganique et Bioinorganique, CNRS-ERS 1824, ICMO, Université de Paris-SUD, Bat 420, 91405, Orsay, France.

PMID: 11681910
DOI: 10.1021/ic0103143

Abstract

The synthesis of four bipodal dihydroxamic acids containing an apical C atom and amide linkages is described, where Ia,b represent "normal" and "retro" hydroxamate isomers: (R)CH[C(=O)NH(CH(2))(2)NHC(=O)(CH(2))(n)()R'](2) (Ia, R = CH(3), R' = N(OH)(C=O)CH(3), n = 2; Ib, R = CH(3), R' = (C=O)N(OH)CH(3), n = 2; Ic, R = CH(3), R' = (C=O)N(OH)CH(3), n = 3; Id, R = C(4)H(9), R' = (C=O)N(OH)CH(3), n = 2.). The pK(a1) and pK(a2) values in aqueous solution are reported, and some degree of cooperativity is noted. Complexation equilibria with Fe(aq)(3+) are described, and values for stepwise and overall equilibrium constants are reported. log beta(230) values for Ia-d are 59.22, 59.45, 58.91, and 58.46, slightly lower than for rhodotorulic acid, although the pFe values for the synthetic siderophores are comparable to that for rhodotorulic acid.