Effect of substituents on the melting points and spectroscopic characteristics of some popular scintillators

The melting points of several fluorescent chromophores, such as anthracene, several p-oligophenylenes, and BBD, have been dramatically reduced by the addition of alkyl or vinyl substituents. In the case of anthracene and p-terphenyl, the melting points of a number of derivatives are below room temperature. Some of the desirable characteristics that accompany these structural modifications are a dramatic increase in solubility in aromatic solvents and a greater immunity to self-quenching and quenching by high Z atoms. In all cases, the substituents have been so positioned that the favorable fluorescence characteristics of the parent chromophore have not been impaired.