Analysis of Solid‐State Luminescence Emission Amplification at Substituted Anthracenes by Host–Guest Complex Formation

Small robust organic molecules showing solid‐state luminescence are promising candidates for optoelectronic materials. Herein, we investigate a series of diphenylphosphanyl anthracenes [9‐PPh 2 ‐10‐R‐(C 14 H 8 )] and their sulfur oxidised analogues. The oxidation causes drastic changes in the molecular structure as the new orientation of the bulky (S)PPh 2 substituent induces a strong butterfly bent structure of the anthracene core, which triggers a strong bathochromic shift resulting in a green solid‐state fluorescence. As the emission properties change only slightly upon aggregation the origin of the emission is attributed to a typical monomer fluorescence. The host–guest complexes of [9‐(S)PPh 2 ‐10‐Ethyl‐(C 14 H 8 )] with four basic arenes reveal an emission enhancement up to five‐times higher quantum yields compared to the pure host. Less interchromophoric interactions and a restriction of intramolecular motion within the host molecules due to fixation by weak C−H⋅⋅⋅π interactions with the co‐crystallised arene are responsible for that emission enhancement.