Time-resolved emission studies of tris-acetylpyrene derivative of a cryptand exhibiting localised monomer, intramolecular exciplex and intramolecular excimer emissions in different environments

The tris-acetylpyrene derivative of a heteroditopic cryptand is found to be a rare supramolecular system exhibiting three emissions due to localised monomer, intramolecular exciplex and excimer emissions in different environments. The lifetime for the monomer emission is much shorter compared to that of free pyrene indicating PET from cryptand moiety to pyrene units. In presence of some transition metal ions, PET is blocked resulting in increase of the lifetime for the metal complex. The major component of the lifetime of the intramolecular exciplex is comparable with that of other polycyclic aromatic tertiary amine systems. Presence of protons in the environment facilitate intramolecular excimer formation whose lifetime is almost twice as that of the intramolecular exciplex emission of the system.