Supramolecular Analytical Chemistry

Contact: Prof. Ivo Leito, ivo.leito@ut.ee

Design and synthesis of new anion receptors

Our supramolecular analytical chemistry research focuses on the design and synthesis of sensitive and selective anion binding receptors. Initial research was first started in our group in 2012 and was mainly based on indolocarbazole based receptors and the acetate anion as a target analyte. From 2013 we started to include more urea and carbazole fragments and increase the diversity of structures both from receptors and anions. Since 2016 we have additionally researched macrocyclic architectures.

In our design process, we start with in silico investigation of receptors. This helps us predict structures for champion molecules that have the potential to be included as ionophores in electrodes. We also include COSMO-RS investigations when studying the binding processes of receptor-analyte complexes.

Quantifying binding in solution

We are focused mostly on carboxylate anion binding and especially on differentiating between different carboxylate anions. Starting from small formate to larger non-steroidal anti-inflammatory drugs (NSAID) such as ibuprofen and naproxen. We incorporate both acyclic and macrocyclic approaches to our receptor design by using combinations of carbazole and urea moieties in the receptor framework.

One of our main advancements in this field has been the development of two highly accurate binding affinity measurement methods: UV-Vis spectrophotometric binding affinity measurement method and NMR spectrometric binding affinity measurement method. Instead of measuring binding constant directly, differences between binding affinities between two or more receptors towards target analyte are measured. Such technique enables overcoming some of the systematic effects associated with absolute binding constant measurements and obtaining binding constant values with much higher accuracy.

Development of anion sensors

In recent years, we have become more focused on providing physical applications for our receptors. Our recent publications, in collaboration with the group of prof. Johan Bobacka at Åbo Akademi, describe our success in constructing potentiometric ion-selective electrode prototypes. Our developed sensors show selectivity towards acetate and benzoate.

As binding anions in sensor membranes is a more complex phenomenon than that in solution, we also dedicate our research to investigating factors influencing binding in membranes, such as lipophilicity.