Cyclic pentaphenylalanine was studied as an efficient anion sensor for halides, thiocyanate and oxoanions in acetonitrile and methanol. Stability constants of the corresponding complexes were determined by means of fluorimetric, spectrophotometric, H-1 NMR, and microcalorimetric titrations. A detailed structural overview of receptor-anion complexes was obtained by classical molecular dynamics (MD) simulations. The results of H-1 NMR and MD studies indicated that the bound anions were coordinated by the amide groups of cyclopeptide, as expected. Circular dichroism (CD) titrations were also carried out in acetonitrile. To the best of our knowledge, this is the first example of the detection of anion binding by cyclopeptide using CD spectroscopy. The CD spectra were calculated from the structures obtained by MD simulations and were qualitatively in agreement with the experimental data. The stoichiometry of almost all complexes was 1:1 (receptor:anion), except for dihydrogen phosphate where the binding of dihydrogen phosphate dimer was observed in acetonitrile. The affinity of the cyclopeptide receptor was correlated with the structure of anion coordination sphere, as well as with the solvation properties of the examined solvents.

Anion-Sensing Properties of Cyclopentaphenylalanine / I. Petters, M. Modrušan, N. Vidović, I. Crnolatac, N. Cindro, I. Piantanida, G. Speranza, G. Horvat, V. Tomišić. - In: MOLECULES. - ISSN 1420-3049. - 27:12(2022 Jun 18), pp. 3918.1-3918.16. [10.3390/molecules27123918]

Anion-Sensing Properties of Cyclopentaphenylalanine

G. Speranza;
2022

Abstract

Cyclic pentaphenylalanine was studied as an efficient anion sensor for halides, thiocyanate and oxoanions in acetonitrile and methanol. Stability constants of the corresponding complexes were determined by means of fluorimetric, spectrophotometric, H-1 NMR, and microcalorimetric titrations. A detailed structural overview of receptor-anion complexes was obtained by classical molecular dynamics (MD) simulations. The results of H-1 NMR and MD studies indicated that the bound anions were coordinated by the amide groups of cyclopeptide, as expected. Circular dichroism (CD) titrations were also carried out in acetonitrile. To the best of our knowledge, this is the first example of the detection of anion binding by cyclopeptide using CD spectroscopy. The CD spectra were calculated from the structures obtained by MD simulations and were qualitatively in agreement with the experimental data. The stoichiometry of almost all complexes was 1:1 (receptor:anion), except for dihydrogen phosphate where the binding of dihydrogen phosphate dimer was observed in acetonitrile. The affinity of the cyclopeptide receptor was correlated with the structure of anion coordination sphere, as well as with the solvation properties of the examined solvents.
1H NMR; MD simulations; UV spectrometry; anion binding; circular dichroism; cyclopeptide; fluorimetry; solvent effect
Settore CHIM/06 - Chimica Organica
Settore CHIM/02 - Chimica Fisica
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/2434/950018
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