On 25 August at 10 Sandip Ashokrao Kadam will defence a PhD thesis titled "Anion receptors: Synthesis and accurate binding measurements" in chemistry in the Faculty of Science and Technology in the University of Tartu.
Thesis supervisor: Professor Ivo Leito (PhD), University of Tartu
Opponent: Professor Carsten Schmuck (Dr), University of Duisburg-Essen, Germany
The current dissertation focused on synthesis of different types of molecular receptors for anions, based on different binding moieties, such as urea, thiourea, carbazole, indole, indolocarbazole, as well as their combinations and on development of a novel accurate NMR-based binding affinity measurement method using the relative binding approach. Measuring the relative binding affinity instead of absolute binding affinity it is possible to obtain highly accurate result because many sources of uncertainty such as ion-pairing and homoconjugation cancel out. The method was applied to the measurement of 38 synthetic receptors towards lactate, benzoate, acetate and trimethylacetate anions in 0.5% H2O:DMSO-d6 with excellent consistency parameters around 0.01.
The results indicate that on the anion side the binding affinity is largely determined by the anion basicity, higher is the anion basicity, stronger is the binding. The binding affinity orders increasing from lactate benzoate acetate trimethylacetate. Nevertheless, there are a number of occasion binding affinity order changes with changing the carboxylate anions, especially in the case of acetate and trimethylacetate anions.
The applicability and advantages of the NMR method for measuring the relative binding affinity have been demonstrated: no need to measure the activity of anion and receptor concentration, high accuracy, robust, possible to see the receptor deprotonation and possible to measure up to six receptors in one solution.