^(129)Xe hyperpolarized gas chemical exchange saturation transfer (HyperCEST) MRI has been suggested as molecular imaging modality but translation to in vivo imaging has been slow, likely due to difficulties of synthesizing suitable molecules. Cucurbit[6]uril-either in readily available non-functionalized or potentially in functionalized form-may, combined with ^(129)Xe HyperCEST MRI, prove useful as a switchable ^(129)Xe MR contrast agent but the likely differential properties of contrast…