Laboratoire de Chimie, UMR 5182 CNRS, ENS-Lyon, 46 allée d'Italie, 69364, Lyon cedex 07, France.
Magn Reson Chem. 2013 Oct;51(10):641-8. doi: 10.1002/mrc.3994. Epub 2013 Aug 16.
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.
我们提出了一种方法来拟合化学位移滴定实验获得的曲线，该方法基于三步络合机制。为此，我们实现了一种拟合程序，该程序基于非线性最小二乘拟合方法，使用“粗网格搜索”方法确定最佳拟合曲线，并提供与实验精度兼容的络合模型不同参数的分布。该分析协议首先在理论数据集上进行了描述和验证。我们展示了它能够收敛到模拟反应方案的真实参数值，并评估络合常数以及多维不确定性的能力。然后，我们将该协议应用于通过 NMR 滴定实验在水溶液中研究镧系元素配合物与三个不同模型分子之间的超分子相互作用。我们表明，在所分析过程中生成的参数分布的不确定性范围内，可以区分镧系元素衍生物与每个模型分子之间的亲和力，并提出相应的热力学常数值。
