Cyclodextrin-Isolated Alkynylpyrenes as UV-Stable and Blue-Light-Emitting Molecules Even in Condensed States

Encapsulation of
highly emissive alkynylpyrenes with permethylated
α-cyclodextrin (PM-α-CD) followed by capping reaction
yielded alkynylpyrene-based [3]­rotaxanes. The [3]­rotaxane emitted
only blue light of monomeric pyrene under various circumstances such
as lipophilic, hydrophilic, and even condensed states and exhibited
extremely high stability for UV irradiation. These properties would
result because PM-α-CD, like bulletproof glass, protected the
alkynylpyrene core from the attack of another excited alkynylpyrene
and singlet oxygen generated by the energy transfer from the excited
alkynylpyrene.