The Uptake and Assembly of Alkanes within a Porous Nanocapsule in Water: New Information about Hydrophobic Confinement

Sivil Kopilevich, Hugo Gottlieb, Keren Keinan-Adamsky, Achim Müller, Ira A. Weinstock

Research output: Contribution to journalArticlepeer-review

21 Scopus citations

Abstract

In Nature, enzymes provide hydrophobic cavities and channels for sequestering small alkanes or long-chain alkyl groups from water. Similarly, the porous metal oxide capsule [{MoVI6O21(H2O)6}12{(MoV2O4)30(L)29(H2O)2}]41- (L=propionate ligand) features distinct domains for sequestering differently sized alkanes (as in Nature) as well as internal dimensions suitable for multi-alkane clustering. The ethyl tails of the 29 endohedrally coordinated ligands, L, form a spherical, hydrophobic "shell", while their methyl end groups generate a hydrophobic cavity with a diameter of 11Å at the center of the capsule. As such, C7 to C3 straight-chain alkanes are tightly intercalated between the ethyl tails, giving assemblies containing 90 to 110 methyl and methylene units, whereas two or three ethane molecules reside in the central cavity of the capsule, where they are free to rotate rapidly, a phenomenon never before observed for the uptake of alkanes from water by molecular cages or containers. In the porous metal oxide capsule [{MoVI6O21(H2O)6}12{(MoV2O4)30(L)29 (H2O)2}]41- (L=propionate), the ethyl tails of the endohedrally coordinated ligands form a spherical, hydrophobic shell, while their methyl end groups generate a hydrophobic cavity at the center of the capsule. Whereas C7 to C3 alkanes are tightly intercalated between the ethyl tails, two or three rapidly rotating ethane molecules reside in the central cavity.

Original languageEnglish
Pages (from-to)4476-4481
Number of pages6
JournalAngewandte Chemie - International Edition
Volume55
Issue number14
DOIs
StatePublished - 24 Mar 2016

Keywords

  • alkanes
  • confinement effect
  • hydrophobicity
  • molybdenum
  • porous capsules

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