Photophysical properties of phenanthro[9,10-d]imidazole-type fluorescent hosts upon inclusion of organic solvent molecules

The crystal of phenanthro[9,10-d]imidazole-type fluorescent clathrate host (1) exhibits fluorescence enhancement behavior with a blue-shift of the emission maximum upon enclathration of organic solvent molecules such as 1-butanol and morpholine, whereas the crystal of 1 exhibits fluorescence enhancement behavior with a red-shift of the emission maximum upon enclathration of carboxylic acid such as acetic acid and propionic acid. The crystal structures of the guest-free and the guest-inclusion compounds of 1 have been determined by X-ray analysis. On the bases of the spectral data and the crystal structures, the effects of the enclathrated guest molecule on the solid-state photophysical properties of the guest-inclusion compounds are discussed.