Luminescent Liquid Crystals Derived from 9,10-Bis(Phenylethynyl) anthracene

Liquid crystalline behavior has been found in a series of low-molecular-weight 9,10-disubstituted anthracenes. In particular, nematic mesomorphism is displayed by derivatives bearing at least a 4ʹ-pentylbiphenyl-4-ylethynyl group, showing that the presence of this substituent induces a mesophase despite the broad central core of the anthracene skeleton. These compounds can also be seen as derived from the known fluorescent material 9,10-bis(phenylethynyl)anthracene (BPEA) with a ppentylphenyl substituent (among others) along its long axis. A comparison of the optical properties of the compounds relative to the parent compound BPEA is presented in order to evaluate their applications in emissive devices. A study of a nematic compound in solution, PMMA film, and pure state in the different phases shows high fluorescence in solution in the green region that slightly shifts to higher wavelengths in PMMA films, but it is clearly red-shifted in pure state.