Naslov
Thermodynamics of complexation of alkali-metal cations by calix[4]arene amide derivatives

Autori
Horvat, Gordan ; Cindro, Nikola ; Frkanec, Leo ; Tomišić, Vladislav

Vrsta, podvrsta i kategorija rada
Sažeci sa skupova, sažetak, znanstveni

Izvornik
24. Congress of Chemists and Technologists of Macedonia : Book of Abstracts / Hadzi Jordanov, Svetomir ; Tomovska, Elena - Skopje : Society of Chemists and Technologists of Macedonia, 2016

ISBN
978-9989-760-13-6

Skup
24. Congress of Chemists and Technologists of Macedonia

Mjesto i datum
Ohrid, Sjeverna Makedonija, 11.09.2016. - 14.09.2016

Vrsta sudjelovanja
Predavanje

Vrsta recenzije
Međunarodna recenzija

Ključne riječi
calixarenes ; complexation ; thermodynamics ; hydrogen bonding ; solvation

Sažetak
Calixarenes are macrocyclic oligomers which consist of four or more phenolic residues linked by methylene group in the ortho position. Many calixarene derivatives are known to be very efficient, and, in some cases, selective binders of ions and neutral molecules. Complexation of alkali-metal cations by lower-rim calix[4]arene tertiary-amide derivatives (1, 2) in acetonitrile (MeCN), benzonitrile (PhCN), and methanol (MeOH) was studied at 25 °C by means of microcalorimetry, as well as UV and 1H NMR spectroscopies. Computational (classical molecular dynamics) investigations of the studied systems were carried out as well. The obtained results were compared with those previously obtained by studying complexation abilities of a calix[4]arene secondary-amide derivative (3). The stability constants of 1:1 complexes were determined (the values obtained by different methods being in excellent agreement), as were the corresponding complexation enthalpies and entropies. Both enthalpic and entropic contributions were found to be favourable for the reactions examined. However, thermodynamic stabilities of the complexes were quite solvent dependent (stability decreased in the solvent order: MeCN > PhCN > MeOH), which could be accounted for by considering the differences in the solvation of the ligand as well as free and complexed alkali-metal cations in the solvents used. The strong influence of intramolecular hydrogen bonds formation in compound 3 (not present in ligands 1 and 2) as well that of inclusion of solvent molecules into the calixarene hydrophobic cone were shown to be of great importance in determining the calixarene-cation complex thermodynamic stability. The experimental results were fully supported by those obtained by MD simulations.

Izvorni jezik
Engleski

Znanstvena područja
Kemija

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