Modern Calorimetry: An Invaluable Tool in Supramolecular Chemistry

There is an increasing need for analytical techniques that may provide accurate and detailed information on the interactions driving the formation of supramolecular assemblies. It is shown that calorimetry is unique in that it may provide the binding constant, the enthalpy change and, in some cases, the stoichiometry of a reaction in a single experiment. The advantages and limitations of calorimetry, in general, and in particular of isothermal titration calorimetry (ITC) over other techniques (e.g., NMR, spectrophotometry), that may be employed to characterize the binding in supramolecular chemistry, are discussed. The importance of splitting the Gibbs energy change into the enthalpic and entropic contributions is shown discussing the pitfalls presented by the van’t Hoff method. Indications on the design and optimization of a calorimetric experiment, with special emphasis on ITC measurements, are also given. A limited number of examples of supramolecular systems are also presented showing that the information provided by calorimetry (i) can unveil subtle details that would go undetected with other techniques, and (ii) is unrivaled especially when coupled with complementary information from other techniques.