The research work on accurate measurement method of binding constants in supramolecular chemistry carried out by Kristjan Haav (left) in the framework of his AMS master’s thesis has gained international recognition: it has been published by the Journal of Organic Chemistry, one of the most prominent organic chemistry journals: Accurate Method To Quantify Binding in Supramolecular Chemistry K. Haav, S. A. Kadam et. al. J. Org. Chem. 2013, 78, 7796−7808.

Measurement of host-guest binding constants is one of the pillars of supramolecular chemistry and is indispensable for designing smart materials, chemo-sensors, etc. Up to now such measurements are typically made by methods that give absolute binding constant values, but at the same time suffer from serious systematic effects making comparison of data from different research groups very difficult.

Kristjan has developed an approach for accurate and comparable measurement of host-guest binding affinities whereby differences in binding strength (ΔlogKass values) are measured between two host molecules toward a particular guest under identical solvent conditions. Measuring differences instead of absolute values enables obtaining highly accurate results, because many of the uncertainty sources (the solvation/association state of the guest in solution, deviations in solvent composition, etc.) cancel out. As a proof of concept, this method was applied to the measurement of the binding strength of 28 synthetic anion receptors toward acetate in acetonitrile containing 0.5% water. The receptors included differently substituted indolocarbazoles, ureas, thioureas, and some others. A self-consistent (consistency standard deviation 0.04 log units) binding affinity scale (right) ranging for around 2.7 log units was constructed from the results.

This work – published in an organic chemistry journal and belonging to the field of supramolecular chemistry – is a nice demonstration of the ubiquity of importance of reliable measurements.

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