39824-47-0Relevant academic research and scientific papers
Capillary Electrophoresis as a Method for Determining Binding Constants: Application to the Binding of Cyclodextrins and Nitrophenolates
Penn, Sharron G.,Bergstroem, Edmund T.,Knights, Ian,Liu, Gaoyuan,Ruddick, Andrew,Goodall, David M.
, p. 3875 - 3880 (1995)
For analytes involved in dynamic aquilibrium processes, capillary electrophoresis is a powerful method of determining binding constants.Equilibrium constants from capillary electrophoresis for the binding of nitrophenolates to α-cyclodextrin show good agreement with literature values obtained using calorimetric and spectroscopic methods, confirming capillary electrophoresis as a viable method.We show that it is imperative to make viscosity corrections, to study the full binding range, and to use an algorithm which calculates the concentration of free cyclodextrin rather than the total cyclodextrin concentration.Binding constants for analytes in a complex mixture can be determined simultaneously.The methods have been applied to 2-, 3-, and 4-nitrophenolates with native and derivatized α- and β-cyclodextrins, and results provide insight into the binding process.Data analysis methods for capillary electrophoresis are also successfully applied to liquid chromatography with the use of the same selector as mobile phase additive.
Kinetics and Thermodynamics of Inclusion of p-Nitrophenolate with α-Cyclodextrin Measured with Pulse Voltammetry
Nuwer, Michael J.,O'Dea, John J.,Osteryoung, Janet G.
, p. 10070 - 10076 (2007/10/02)
The rate constants and formal equilibrium constant are determined for inclusion of p-nitrophenolate anion into α-cyclodextrin at pH = 13.5, where α-cyclodextrin is 82percent dissociated to the basic (anionic) form.The conditional dissociation constant is 2.99 * 10-3 M (at 20 deg C), about an order of magnitude larger then the value reported for pH 11, where α-cyclodextrin is completely in the acid form.This observation illustrates the importance of Coulombic interactions in substrate-receptor interactions.The values of rate constants, determined from a nonlinear least-squares analysis of the shape of square-wave voltammograms, are kf = 3.5 * 105 s-1 and kb = 1.2 * 108 s-1 M-1 at 20 deg C.This type of analysis is typically precluded by distortion of wave shape due to adsorption of cyclodextrin on the mercury electrode.This artifact was eliminated by optimization of voltammetric parameters and by competitive adsorption of tetramethylammonium ion.Values of diffusion coefficients of p-nitrophenolate in the complexed and uncomplexed forms are 3.28 * 10-6 and 1.05 * 10-5 cm2 s-1, respectively.
