Luminous nematic threads: single-component liquid crystals self-assemble into fluorescent fibers

Abstract

We report the synthesis and mesomorphic behaviour of two new series of liquid crystal dimers derived from N-alkylation of 1,4-phenylenedimethanamine with 4-cyanobiphenyl units linked by aliphatic spacers (n = 4–10). Polarizing optical microscopy, differential scanning calorimetry and X-ray diffraction show that most dimers display nematic phases, with several exhibiting stable supercooled mesophases at room temperature. In thick films, rare ±1 nematic defects drive the spontaneous formation of fluorescent fibers (quantum yield 72.1%), with Schlieren patterns revealing local variations in elasticity and viscosity. This molecular design offers insights into self-assembling luminous nematic fibers for optoelectronic applications.