Quantum Chemical Calculations on Alkali Metal Complexes

Golebiowski, Jérôme; Lamare, V.; Ruiz‐López, Manuel F.

doi:10.1007/0-306-47522-7_18

Cited by 1 publication

(1 citation statement)

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“…It can also be applied through ab initio quantum mechanical calculations, and results on the Cs ϩ /Rb ϩ selectivity of benzo21C7 and tribenzo21C7 in the gas phase will soon be reported. 15 The study reported here is partially related to strain energy, but instead of working on isolated molecular mechanics (MM) structures, we chose to work on molecular dynamics (MD) samplings at 300 K, which give a set of equilibrated conformations coexisting in the same energy minimum, thus giving additional insights into the actual ligand flexibility. The other main advantage is to be able to take into account the influence of solvation on the ligand structure and evaluate its hydrophobicity through interactions with the closest water molecules.…”

Section: Introductionmentioning

confidence: 99%

Molecular dynamics study of 21C7 crown ether derivatives and their alkali cation complexes. Comparison with 1,3-alt-calix[4]arene-crown-6 compounds

Lamare

Haubertin

Golebiowski

et al. 2001

J. Chem. Soc., Perkin Trans. 2

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A molecular dynamics study in vacuo and in an explicit water phase was undertaken on 21C7 benzo and cyclohexano crown ether derivatives, in order to better understand the differences between these compounds and calixarene-crown-6 compounds regarding the complexation of alkali cations. Whatever the number and the position of the benzo or cyclohexano groups on the crown ether, this crown ether remains highly flexible when it is simulated in the gas phase. The most notable differences appear in simulations in an explicit aqueous phase and are discussed in terms of hydrophobicity of the free ligands and instability of non hydrated complexes in water. Calixarene-crown-6 compounds appear to be much better preorganized, with a smaller and less mobile ether loop due to its grafting onto the calixarene cavity. In contrast to the 21C7s, the crown can adapt perfectly only around caesium and penalises sodium particularly. Moreover, the calixarenes isolate better the cations from the bulk aqueous phase. These differences of preorganisation and cation accessibility to the solvent can explain the superior extracting properties and the stronger selectivity of calixcrowns.

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Section: Introductionmentioning

confidence: 99%