Kinetic methods, advantages variable-time

NMR spectral techniques are widely used to study complexation of macrocycles as well as the thermodynamic and kinetic quantities that describe host-guest interactions. Measurements of the free energy of activation for complex dissociation (AG. ) at the H NMR coalescence temperature, have been done using a variable temperature H NMR procedure . The method is advantageous for ammonium cations because the dissociation rate for most crown ether-ammonium cation complexes is within the H NMR time scale and only a small amount of sample (3-5 mg) is required. 

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