Development of photoluminescent liquid-crystalline dimers bearing two fluorinated tolane-based luminous mesogens

Fluorinated tolane dimers consisting of two fluorinated tolanes connected by various lengths of an alky-lene tether were designed and synthesized via three reaction steps including an aromatic nucleophilic substitution and a Mitsunobu-type etherification reaction. Although mesophases were not observed in the case of dimers connected by relatively short alkylene tethers, fluorinated tolane dimers with rela-tively long tethers underwent a transition to a nematic liquid crystalline (N LC) phase during cooling. In addition, the fluorinated tolane dimers exhibited photoluminescence (PL), both in solution and in the crystalline (Cr) phase, with efficiencies of up to 0.72. It is noteworthy that the PL behavior of the N phase molecular aggregates was found to be different from that of the Cr phase. These findings suggest a promising route for the development of thermo-responsive photoluminescent liquid crystals (PLLCs) and thermosensing applications of PL materials. (c) 2022 Elsevier B.V. All rights reserved.

Automated summary

Fluorinated tolane dimers connected by relatively long alkylene tethers undergo a transition to a nematic liquid crystalline phase during cooling, exhibiting high photoluminescence efficiency. These findings suggest a promising route for the development of thermo-responsive photoluminescent liquid crystals and thermosensing applications of photoluminescent materials.