Unusual orientation and reactivity of alkyl halides in water-soluble cavitands

Abstract

Water-soluble deep cavitands with ionic peripheral groups take up hydrophobic guest compounds in D₂O. Longer n-halides and α,ω-dihalides C₇–C₁₁, are bound and NMR is used to deduce their arrangements within the cavitand. The guests tumble rapidly on the NMR timescale, but unexpectedly, the halogen atoms compete with CH₃ groups for the aromatic panels near the bottom of the cavitand. Even a thiol can be found in the depths of the cavitand but not hydroxyl groups: 1,12-dodecanediol folds in the space leaving the ends exposed to solvent. The hydrolysis of bound guests is accelerated when the halides are near the cavitand rim.