Highly fluorescent columnar liquid crystals with elliptical molecular shape: oblique molecular stacking and excited-state intramolecular proton-transfer fluorescence

Abstract

We have synthesized a novel class of excited-state intramolecular proton transfer-active molecule (DOXG) forming columnar liquid crystals with enhanced fluorescence emission. The intramolecularly H-bonded core of DOXG produced columnar hexagonal and rectangular phases during cooling as a result of strong core-to-core interactions. In its mesophase, DOXG produced tilted stacking (J-type) in the inner column due to the elliptical molecular shape, bringing about a strong (quantum yield of 34%) and large Stokes' shifted (∼173 nm) fluorescence emission.