Luminescences of Pyrene Single Crystal and Pyrene Molecules Inserted in a Molecular Vessel of Cyclodextrin

Abstract

Highly purified single crystals of pyrene were made by a gas phase crystal growth method from 180 times of zone-refined pyrene. The dry powder of -cyclodextrin including a pyrene single molecule and that of -cyclodextrin including twin molecules were prepared under vacuum. The luminescence spectra of pyrene single molecules, twin molecules and single crystals, and their temperature dependences were measured with great care in the process of cooling the samples. It is found that the features of luminescence spectra at 2 K are quite different from each other. Pyrene twin molecules in -cyclodextrin show an excimer luminescence similar to that of single crystal. The vibronic luminescence in the range of 3.0 -3.5 eV comes from the ground-excited-state complex, or in other words, from the vibronic exciton, in contrast to the hitherto-assigned luminescence from another type of selftrapped exciton or metastable B-state which is the precursor of selftrapped excitons.

Growth and characterization of pyrene crystals on carbon nanofibers

“…Furthermore, according to the report by Takahashi et al, the fluorescence of the pyrene single crystals indicates the same excimer-like fluorescence as that of the original pyrene polycrystals [34]. Therefore, the fluorescence having a peak at 460 nm in Supernatant A will be attributed to the pyrene single crystals.…”

Cyclodextrins

“…No complex formation was observed for α-cyclodextrin. 46 Even larger polycyclic aromatic hydrocarbons have been shown to form complexes with cyclodextrins, for example benzoperylene forms complexes in aqueous solution with β-cyclodextrin 47 and perylene has been shown to form a 1 : 2 complex in aqueous solution with γ-cyclodextrin, 48 as does the even larger coronene 49 in a water-methanol mixture. The yields of this reaction are greatly enhanced when the anthracenes are irradiated whilst incorporated in cyclodextrin complexes compared to when they are in simple aqueous solution, indicating that the molecules are held in close proximity to each other.…”