Circularly polarised luminescence from excimer emission of anthracene derivatives complexed with γ-cyclodextrin in the solid state

In this study, we report circularly polarised luminescence (CPL)-active molecules that exhibit high fluorescence quantum yields in the solid state. We developed anthracene derivatives with substituents at the 9 and 10 positions, such as ethyl(anthracene-9-carbonyl)glycinate (9AnGlyEt), N-butylanthracene-9-carboxamide (9AnB), N-benzylanthracene-9-carboxamide (9AnPh), and N-9,N-10-dibutylanthracene-9,10-dicarboxamide (9,10AnB). These compounds were complexed with gamma-cyclodextrin (gamma-CD) in the solid state by grinding, and the fluorescence properties of the resulting gamma-CD complexes were investigated. The fluorescence quantum yields were enhanced after gamma-CD complexation. Among the prepared gamma-CD complexes, 9AnGlyEt/gamma-CD had the highest fluorescence quantum yield (phi(f) = 0.35), which was enhanced up to 5.8 times after gamma-CD complexation. This was probably due to the interaction between the two anthracene molecules in the gamma-CD cavity, which prevented fluorescence quenching caused by aggregation of the compounds. Positive CPL of g(CPL) = 1.3 x 10(-3) was observed for 9AnGlyEt/gamma-CD based on its excimer emission.