Emissive Liquid Crystalline Boron C,N-Chelates: Synthesis, Self-assembly and Photophysical Properties

A library of novel phenylpyridine-based boron C,N-chelates bearing a mesogenic unit was synthesized and investigated to clarify how the chain type, length and number as well as the boron substitution (BH2 vs. BMe2) influence the mesomorphic and photophysical behavior. All BH₂ derivatives exhibited SmA or N phases even with short alkyl chains, whereas BMe₂ analogues remained non-mesomorphic unless a semi-perfluorinated chain was introduced, demonstrating the strong influence of boron substitution on mesophase formation. All compounds displayed intense blue emission in solution, with spectral properties primarily determined by the boron C,N core and only minor shifts induced by variation in the mesogenic unit. Quantum yields reached up to 100% in solution. These results demonstrate that mesomorphic behavior can be introduced and tuned while preserving the excellent photophysical performance of the boron-C,N-chelate system.