Room-Temperature Alkyl-Diphenylpyrene Liquefication by Molecular Desymmetrization

Achieving the lowest phase transition temperature with minimal chemical modification in highly crystalline & pi;-conjugated molecules is a universal problem in related research fields. This paper reports room-temperature liquefication of diphenylpyrene isomers by introducing bulky yet flexible branched alkyl chains through molecular desymmetrization. Six isomers with different symmetries depending on the positions of the phenyl groups and alkyl groups were synthesized, and three of the isomers were found to be liquids at 25 & DEG;C, a state in which they have remained for more than five years. Although it is generally believed that the lower the symmetry of a molecule, the less likely it is to crystallize, one molecule with a relatively high molecular symmetry unexpectedly did not crystallize, which was evidenced by the kinetic inhomogeneity of this amorphous material (practically stable liquid) assessed by rheological analysis.

Automated summary

This paper presents the room-temperature liquefaction of diphenylpyrene isomers by introducing bulky yet flexible branched alkyl chains through molecular desymmetrization. Six isomers with different symmetries were synthesized, and three of them were found to be liquids at 25°C and have remained in this state for more than five years. The unexpectedly non-crystallizing molecule with relatively high molecular symmetry was confirmed by rheological analysis of the amorphous material's kinetic inhomogeneity.