Selective Binding and Isomerization of Oximes in a Self-Assembled Capsule.

A series of straight-chain (C7-C13) alkyl--methyl aldoximes (R-C(H)═NOMe) were synthesized with various functional groups at the remote ends (alkenes, halogen, -COOH, and NH). Their isomers about the C═N bond showed ∼60-40% -ratio in organic solutions. Surprisingly, their confinement in a water-soluble capsule with benzoselenodiazole walls shows high selectivity for the -/-isomer. Their relative affinities for the chalcogen-bonded capsule at room temperature depend mainly on the guest chain length and functional groups. A chain length of 14 heavy atoms showed especially high to -isomer selectivity (>99%) and was used in separation. The - isomerization occurred only in the capsular cavity at room temperature and was accelerated 10-fold by sonication. The -isomer selective binding, separation, and - isomerization are supported by NMR, DOSY, and computational studies.