Phase-dependent emission of naphthalene-anthracene-based concave-shaped molecules

Fluorescence spectra of aromatic chain imides possessing anthracene and naphthalene moieties were examined both in solution and in the solid state. Depending on the substituents at the imide nitrogen atom, their fluorescence spectra varied in the solid state. However, their spectra in solution were almost identical. In solution, emission corresponding to a naphthalene-anthracene exciplex was observed. In contrast, the imides possessing an intermolecular anthracene-anthracene interaction exhibited red-shifted fluorescence in the solid state. This red-shifted fluorescence could originate in an anthracene excimer or the exciplex formed from a sum of fluorophores. In contrast, compounds without this anthracene-anthracene interaction in the solid state had very similar solution and solid-state fluorescence spectra.