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Updated: May 22, 2026

Isothermal Titration Calorimetry for Measuring Macromolecule-Ligand Affinity
Published on: September 7, 2011
Isothermal calorimetric titrations on charge-assisted halogen bonds: role of entropy, counterions, solvent, and
Sebastian M Walter1, Florian Kniep, Laxmidhar Rout
1Department Chemie, Technische Universität München, Garching, Germany.
Abstract:
We have conducted isothermal calorimetric titrations to investigate the halogen-bond strength of cationic bidentate halogen-bond donors toward halides, using bis(iodoimidazolium) compounds as probes. These data are intended to aid the rational design of halogen-bond donors as well as the development of halogen-bond-based applications in solution. In all cases examined, the entropic contribution to the overall free energy of binding was found to be very important. The binding affinities showed little dependency on the weakly coordinating counteranions of the halogen-bond donors but became slightly stronger with higher temperatures. We also found a marked influence of different solvents on the interaction strength. The highest binding constant detected in this study was 3.3 × 10(6) M(-1).
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