Molecularly Engineered Naphthalimide-Based Liquid Crystals: A Platform for Soft Gelators, Charge Transports, and Bioimaging Applications

Abstract

Molecularly engineered naphthalimide-based room-temperature liquid crystals (NIH1 and NIH2) were developed that unify mesomorphism, organogelation, ambipolar charge transport, and bioimaging within a single soft-matter platform. The dimeric derivative NIH1 acts as a thermo-responsive organogelator in polar organic solvents (ethyl acetate and n-butanol) and stabilizes a room-temperature columnar rectangular phase through efficient π–π stacking and dense space filling. In contrast, the tris(naphthalimide) analog NIH2 forms a high-temperature columnar hexagonal phase and exhibits ambipolar charge transport with balanced hole and electron mobilities, highlighting its potential as a soft semiconductor. Both derivatives display intense blue fluorescence in solution and condensed phases and stain MCF-7 human breast cancer cells with bright intracellular emission, confirming efficient uptake and low cytotoxicity at imaging-relevant doses. The combination of high thermal stability (Td > 365°C), well-defined discotic mesophases, reversible gelation, and biocompatible fluorescence positions these naphthalimide-based liquid crystals as promising candidates for next-generation organic electronic and bioimaging applications.