engleski

Anion binding properties of two pentameric homocyclopeptides in acetonitrile and methanol

A class of macrocyclic compounds that contains amide groups in their backbone and can be used as selective receptors of anionic species are cyclopeptides.[1-2] Rather good complexation properties of these compounds can be attributed to the remarkable hydrogen-bonding donor properties of the amide groups. In addition, the well- structured, yet sufficiently flexible structure of the cyclopeptides, as well as the presence of multiple functional groups oriented in the appropriate direction, with the additional possibility of modifying the peptide backbone and/or the side chains, contribute to the high efficiency and selectivity for anion binding of these receptors. Here we present the studies of halides and oxoanions binding with two penta homocyclopeptide ligands, cyclopentaphenylalanine and cyclopentaleucine. In the case of cyclopentaphenylalanine, binding studies were carried out in acetonitrile by spectrophotometric titrations, making use of the phenyl rings as chromophores, while the affinity of cyclopentaleucine towards anions in methanol was tested by NMR and microcalorimetric titrations. Structural insight regarding the free receptors and their anion complexes was obtained by molecular dynamics simulations. ACKNOWLEDGEMENTS: This work was supported by the Croatian Science Foundation under project IP-2019- 04-9560 (MacroSol). REFERENCES [1] G. Horvat, S. Tarana, N. Vidović, N. Cindro, G. Speranza, V. Tomišić, J. Mol. Liq. 2021, In Press [2] R. B. P. Elmes, K. A. Jolliffe, Chem. Commun. 2015, 51, 4951–4968

anion-binding ; cyclohomopeptides ; MD simulation ; NMR ; spectrophotometry ; thermodynamics

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