title: A multidimensional approach to the analysis of chemical shift titration experiments in the frame of a multiple reaction scheme.
abstract: We present a method for fitting curves acquired by chemical shift titration experiments, in the frame of a three-step complexation mechanism. To that end, we have implemented a fitting procedure, based on a nonlinear least squares fitting method, that determines the best fitting curve using a "coarse grid search" approach and provides distributions for the different parameters of the complexation model that are compatible with the experimental precision. The resulting analysis protocol is first described and validated on a theoretical data set. We show its ability to converge to the true parameter values of the simulated reaction scheme and to evaluate complexation constants together with multidimensional uncertainties. Then, we apply this protocol to the study of the supramolecular interactions, in aqueous solution, between a lanthanide complex and three different model molecules, using NMR titration experiments. We show that within the uncertainty that can be evaluated from the parameter distributions generated during our analysis, the affinities between the lanthanide derivative and each model molecule can be discriminated, and we propose values for the corresponding thermodynamic constants.
authors: Laboratoire de Chimie, UMR 5182 CNRS, ENS-Lyon, 46 allée d'Italie, 69364, Lyon cedex 07, France.
authors: Anthony
authors: A
authors: D'Aléo
authors: Elise
authors: E
authors: Dumont
authors: Olivier
authors: O
authors: Maury
authors: Nicolas
authors: N
authors: Giraud
keywords: NMR 1H; fast exchange; many parameter curve fitting; multidimensional error bar; paramagnetic shift; thermodynamic constants determination; titration experiment