Naslov
Solvent effect on complexation of alkali-metal cations by a calix[4]arene amide derivative

Autori
Horvat, Gordan ; Stilinović, Vladimir ; Kaitner, Branko ; Frkanec, Leo ; Tomišić, Vladislav

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

Skup
44th World Chemistry Congress

Mjesto i datum
Istanbul, Turska, 11.08.2013. - 16.08.2013

Vrsta sudjelovanja
Predavanje

Vrsta recenzije
Međunarodna recenzija

Ključne riječi
calixarene ; alkali-metal cations ; complexation ; thermodynamics ; solvation

Sažetak
Complexation of alkali-metal cations by a lower- rim calix[4]arene secondary-amide derivative (L) in benzonitrile (PhCN) and methanol (MeOH) was studied at 25 °C by means of microcalorimetry, UV and 1H NMR spectroscopies, and single-crystal X- ray diffraction. Classical molecular dynamics simulations (MD) of the systems studied were carried out as well. The results of these investigations were compared with those obtained previously for acetonitrile (MeCN) as a solvent. The stability constants of 1:1 ML+ 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 ML+ 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. Interestingly, macrocycle L was proven to be a better binder of Li+ compared to Na+ in PhCN, which was in contrast to MeCN as a solvent. That could be explained by the inclusion of a PhCN molecule into the ligand hydrophobic cone of the LiL+ complex observed in the solid state. More precisely, in the molecular structure of the lithium complex of L determined by the X-ray diffraction analysis, the PhCN molecule bound in the calixarene basket was found to coordinate the Li+ cation by its nitrile group, which is energetically quite favourable. The experimental results were supported by those obtained by MD simulations.

Izvorni jezik
Engleski

Znanstvena područja
Kemija

POVEZANOST RADA