Using steady-state and time-resolved fluorescence spectroscopy, we investigated the intermolecular coupling between mesogenic biphenyl-ester moieties of a thermotropic liquid crystal under phase transition. In the crystalline-to-smectic C transition, a broad excitation band centered at 280 nm and a fluorescence redshift by 25 nm, followed by a drastic change in the fluorescence time-decay constant (from ∼90 to ∼230 ps), are consistently observed. These changes result from the intermolecular configurational change from biphenyl-biphenyl to biphenyl-ester. Emissions from intermolecular complexes such as J-aggregated biphenyls in crystalline and biphenyl-ester exciplexes in smectic C, smectic A, and isotropic phases are characterized.
All Science Journal Classification (ASJC) codes
- Physics and Astronomy(all)
- Physical and Theoretical Chemistry