Synthesis, binding properties and theoretical studies of p-tert-butylhexahomotrioxacalix[3]arene tri(adamantyl)ketone with alkali, alkaline earth, transition, heavy metal and lanthanide cations

Marcos, Paula M.; Ascenso, José R.; Segurado, Manuel A.P.; Bernardino, Raul J.; Cragg, Peter J.; Bernardino, Raul

http://hdl.handle.net/10400.8/12798

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Synthesis, binding properties and theoretical studies of p-tert-butylhexahomotrioxacalix[3]arene tri(adamantyl)ketone with alkali, alkaline earth, transition, heav.pdf	p-tert-Butylhexahomotrioxacalix[3]arene tri(adamantyl)ketone (1b) was synthesized for the first time. Compound 1b was obtained in a cone conformation in solution at room temperature, as established by NMR spectroscopy (1H and 13C). The binding properties of ligand 1b for alkali, alkaline earth, transition, heavy metal and lanthanide cations have been assessed by phase transfer and proton NMR titration experiments. Molecular mechanics and ab initio techniques were also employed to complement the NMR data. The results are compared to those obtained with other closely related homooxacalixarene derivatives. Although triketone 1b is a weak extractant, it shows a strong peak selectivity for Na+ and also some preference for Ag+. Proton NMR titrations indicate the formation of 1:1 complexes between 1b and the cations studied, and also that they should be located inside the cavity defined by the phenoxy and carbonyl oxygen atoms. Although the molecular mechanics results show little correlation with the NMR data, a good agreement was obtained with the ab initio models.	502.67 KB	Adobe PDF	Download

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Authors

Marcos, Paula M.

Ascenso, José R.

Segurado, Manuel A.P.

Bernardino, Raul J.

Cragg, Peter J.

Bernardino, Raul

Abstract(s)

p-tert-Butylhexahomotrioxacalix[3]arene tri(adamantyl)ketone (1b) was synthesized for the first time. Compound 1b was obtained in a cone conformation in solution at room temperature, as established by NMR spectroscopy (1H and 13C). The binding properties of ligand 1b for alkali, alkaline earth, transition, heavy metal and lanthanide cations have been assessed by phase transfer and proton NMR titration experiments. Molecular mechanics and ab initio techniques were also employed to complement the NMR data. The results are compared to those obtained with other closely related homooxacalixarene derivatives. Although triketone 1b is a weak extractant, it shows a strong peak selectivity for Na+ and also some preference for Ag+. Proton NMR titrations indicate the formation of 1:1 complexes between 1b and the cations studied, and also that they should be located inside the cavity defined by the phenoxy and carbonyl oxygen atoms. Although the molecular mechanics results show little correlation with the NMR data, a good agreement was obtained with the ab initio models.

Keywords

Calixarenes Hexahomotrioxacalix[3]arene ketone Metal cation extraction Proton NMR titration Molecular mechanics Ab initio

URI

http://hdl.handle.net/10400.8/12798

Citation

Paula M. Marcos, José R. Ascenso, Manuel A.P. Segurado, Raul J. Bernardino, Peter J. Cragg, Synthesis, binding properties and theoretical studies of p-tert-butylhexahomotrioxacalix[3]arene tri(adamantyl)ketone with alkali, alkaline earth, transition, heavy metal and lanthanide cations, Tetrahedron, Volume 65, Issue 2, 2009, Pages 496-503, ISSN 0040-4020, https://doi.org/10.1016/j.tet.2008.11.005.