Determination of second-order association constants by global analysis of 1H and 13C NMR chemical shifts.

Al‐Soufi, Wajih; Jover, Aida; Budal, Rosane Maria; Tato, José Vázquez

doi:10.1016/s0039-128x(02)00114-9

Cited by 34 publications

(22 citation statements)

References 63 publications

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“…Similarly to what has been reported elsewhere for the determination of second‐order complexation constants, the correlation between adjustable parameters leads to a broad ensemble of fitting curves that allow to reproduce the observed chemical shifts . We remind that this is mainly because in such three‐step interaction model, changes in a given parameter can be compensated by a change in another parameter while producing the same values .…”

Section: Application To the Analysis Of Binding Constantssupporting

confidence: 61%

“…Similarly to what has been reported elsewhere for the determination of second-order complexation constants, the correlation between adjustable parameters leads to a broad ensemble of fitting curves that allow to reproduce the observed chemical shifts. [10] We remind that this is mainly because in such threestep interaction model, changes in a given parameter can be compensated by a change in another parameter while producing the same values. [9] We also remark that as expected, the "shape" of the distributions is not symmetric and, in particular, is not centered around the best fit values due to the complexity of the relationship between the different parameters in the interaction model.…”

Section: Application To the Analysis Of Binding Constantsmentioning

confidence: 99%

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A multidimensional approach to the analysis of chemical shift titration experiments in the frame of a multiple reaction scheme

D’Aléo

Dumont

Maury

et al. 2013

Magnetic Reson in Chemistry

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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.

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Section: Application To the Analysis Of Binding Constantssupporting

confidence: 61%

Section: Application To the Analysis Of Binding Constantsmentioning

confidence: 99%

A multidimensional approach to the analysis of chemical shift titration experiments in the frame of a multiple reaction scheme

D’Aléo

Dumont

Maury

et al. 2013

Magnetic Reson in Chemistry

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show abstract

“…To increase the accuracy in the value of the fitted parameters, global fits [51] of the chemical shifts of the H 3 and H 5 b-CD nuclei, obtained from the methods of titration and continuous variation (c.f. Fig.…”

Section: Binding Constantsmentioning

confidence: 99%

The effect of the head-group spacer length of 12-s-12 gemini surfactants in the host–guest association with β-cyclodextrin

Carvalho

Correia

Valente

et al. 2011

Journal of Colloid and Interface Science

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“…3 The effect of the correlation between parameters can be visualized by studying the behavior of 2 as a function of the υ obs values. 21 The LiClO 4 /12C4/CH 3 CN experimental data were used as a starting point to explore the confidence limits on and correlations among the model parameters for this nonlinear model (Eqn 14).…”

Section: Propagation Of Errorsmentioning

confidence: 99%

“…14 Statistical correlations between the adjustable parameters in the fitting function can also lead to unreliable values for stability constants. 3 This means that changes in one parameter can be compensated by changing one of the other parameters without causing a significant change in the predicted chemical shift. This situation is especially prevalent when the number of adjustable parameters increases with higher order reactions.…”

Section: Introductionmentioning

confidence: 99%

Stability constants: comparative study of fitting methods. Determination of second‐order complexation constants by²³Na and⁷Li NMR chemical shift titration

Masiker

Mayne

Eyring

2006

Magnetic Reson in Chemistry

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NMR chemical shift titration has been widely used as a method for the determination of stability constants. Systems involving metal-ligand complexation have been investigated using a number of methodologies. There are significant differences in the values reported for stability constants obtained by different experimental methods, such as calorimetry and ion selective electrode (ISE) titrations; nor has NMR chemical shift titration always yielded consistent results. Different researchers have obtained different results for the same system with results differing by as much as an order of magnitude. The chemical shift data are generally plotted against the concentration ratio of the metal and ligand for a set of solutions. A nonlinear least squares fitting method using an analytical solution of the cubic equation for the equilibrium concentration of the free ligand is used in this study and compared with methods used in the literature. Second-order association constants for the LiClO(4):12-crown-4 system in acetonitrile and the NaClO(4):12-crown-4 system in methanol are reported. Formation of both 1:1 and 1:2 metal-ligand complexes are considered. The LiClO(4):12-crown-4 acetonitrile system had been investigated previously by NMR titration but only 1:1 complexation was considered in that study. This study provides convincing evidence that both 1:1 and 1:2 complexes are important, at least, in the lithium system. A Monte Carlo investigation of the propagation of errors from the chemical shifts to the stability constants shows that the choice of data analysis methods may, in part, contribute to discrepancies and that the nonlinear nature of the model can dramatically affect the error limits on the stability constants.

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Determination of second-order association constants by global analysis of 1H and 13C NMR chemical shifts.

Cited by 34 publications

References 63 publications

A multidimensional approach to the analysis of chemical shift titration experiments in the frame of a multiple reaction scheme

A multidimensional approach to the analysis of chemical shift titration experiments in the frame of a multiple reaction scheme

The effect of the head-group spacer length of 12-s-12 gemini surfactants in the host–guest association with β-cyclodextrin

Stability constants: comparative study of fitting methods. Determination of second‐order complexation constants by²³Na and⁷Li NMR chemical shift titration

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Determination of second-order association constants by global analysis of 1H and 13C NMR chemical shifts.

Cited by 34 publications

References 63 publications

A multidimensional approach to the analysis of chemical shift titration experiments in the frame of a multiple reaction scheme

A multidimensional approach to the analysis of chemical shift titration experiments in the frame of a multiple reaction scheme

The effect of the head-group spacer length of 12-s-12 gemini surfactants in the host–guest association with β-cyclodextrin

Stability constants: comparative study of fitting methods. Determination of second‐order complexation constants by23Na and7Li NMR chemical shift titration

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Stability constants: comparative study of fitting methods. Determination of second‐order complexation constants by²³Na and⁷Li NMR chemical shift titration