Gas-phase fragmentation of 1-adamantylbisimidazolium salts and their complexes with cucurbit[7]uril studied using selectively 2 H-labeled guest molecules.

The structures of two adamantane-based fragments and the mechanisms of their formation were rationalized. Two distinct geometric arrangements for the adamantane cage inside the CB7 cavity were hypothesized to explain the differences in the fragmentation patterns for guests with minimal, moderate, and high steric hindrance. This finding brings new insight into the understanding of intrinsic behavior of the adamantane-based guests inside the CB7 cavity.