Design Strategies for Compact Photoluminescent Liquid Crystals Based on Fluorinated Tolane Frameworks.

Fluorinated tolane derivatives offer rigid and compact π-conjugated frameworks in which electronic structure and intermolecular interactions can be precisely modulated, making them attractive platforms for integrating mesomorphic order and photoluminescence within a single molecular architecture. In this account, we summarize our systematic efforts to establish molecular design strategies for compact fluorinated tolane-based photoluminescent liquid crystals (PLLCs), with a particular focus on controlling molecular aggregation across crystalline and liquid-crystalline phases. Three complementary design approaches are discussed: molecular dimerization to reduce crystallinity and induce mesomorphism, partial fluorination combined with semifluoroalkoxy chains to balance electronic effects and aggregation moedes, and ionic functionalization using imidazolium termini to induce dynamic layered order and counteranion-dependent control. Though these strategies, the roles of fluorination, spacer length, flexible chains, and ionic interactions in governing mesophase stability and solid-state photoluminescence are elucidated. Collectively, these studies demonstrate how hierarchical control of molecular order enables the reconciliation of mesomorphic behavior and efficient emission within compact π-conjugated systems, and they provide general design principles for the development of responsive emissive soft materials.