Extraction and DFT study on the complexation of H3O+ with hexaethyl p-tert-butylcalix[6]arene hexaacetate

✍ Scribed by Jan Lang; Jiří Dybal; Emanuel Makrlík; Petr Vaňura; Soňa Vašíčková; Petr Maloň

• Publisher: Elsevier Science
• Year: 2007
• Tongue: English
• Weight: 985 KB
• Volume: 846
• Category: Article
• ISSN: 0022-2860
• DOI: 10.1016/j.molstruc.2007.01.037

✦ Synopsis

From extraction experiments and c-activity measurements, the extraction constant corresponding to the equilibrium H 3 O + (aq) + 1AE Na + (nb) ¡ 1AEH 3 O + (nb) + Na + (aq) taking place in the two-phase water-nitrobenzene system (1 = hexaethyl p-tert-butylcalix[6]arene hexaacetate; aq = aqueous phase, nb = nitrobenzene phase) was evaluated as log K ex (H 3 O + , 1AENa + ) = À0.6 ± 0.1. Further, the stability constant of the 1AEH 3 O + complex in water saturated nitrobenzene was calculated for a temperature of 25 °C as log b nb (1AEH 3 O + ) = 6.8 ± 0.2. By using quantum mechanical DFT calculations, the most probable structure of the 1AEH 3 O + complex species was predicted. In this complex, the hydroxonium ion H 3 O + is bound partly to three carbonyl oxygen atoms by strong hydrogen bonds and partly to three alternate phenoxy oxygens by somewhat weaker hydrogen bonds.