supraCAR

Development of Supramolecular
Receptors for Cations and Anions


Supramolecular chemistry is the chemistry of the intermolecular bond, covering the structures and functions of the entities formed by association of two or more chemical species. Molecular recognition in the supermolecules formed by receptor-substrate binding rests on the principles of molecular complementarity,

Jean-Marie Lehn in Nobel lecture, 8 December 1987

Research Summary

The importance of development of efficient and selective receptors of charged species has been widely recognised over the last few decades. In the framework of this project, a variety of such compounds will be designed, synthesised, and characterised. A series of novel calixarene derivatives capable of strongly and selectively binding cations and anions will be prepared. Some of these compounds are aimed to be efficient liquid-liquid extraction agents whereas the others will be designed to be water-soluble or to bear fluorescent substituents. As a continuation of our previous work, another class of anion receptors will be synthesised, namely amine, amide, urea, and thiourea derivatives of dehydroacetic acid. The complexation abilities of all the compounds mentioned towards various substrates will be explored in detail by using an integrated approach which includes thermodynamic, computational, and structural studies. A number of experimental methods will be employed, viz. spectrophotometry, fluorimetry, NMR spectroscopy, conductometry, potentiometry, and (micro)calorimetry. That should yield detailed and reliable thermodynamic data (stability constants, reaction and solution Gibbs energies, enthalpies and entropies). In order to facilitate the design of the targeted molecules and to assist the interpretation of the experimental results, the molecular dynamics simulations of the systems studied will be carried out. This will, together with the results of NMR studies and that of solid-state X-ray diffraction investigations, also ensure information about structural characteristics of the receptors and their complexes. Particular attention will be focused on the intra- and intermolecular hydrogen-bonding and solvent effects (especially specific solvent-solute interactions) on the equilibria of binding reactions. For that reason, many solvents with different solvation and hydrogen-bonding affinities will be used. The obtained thermodynamic information is expected to provide a detailed insight into the complexation processes and the influence of medium on the reactions studied, which will allow further development of efficient supramolecular receptors.