A tunable photoluminescence system consisting of liquid-crystalline trans-alkoxy-nitrostilbenes with n-alkyl chains

A correlation between molecular arrangements and photoluminescence properties of trans-alkoxy-nitrostilbenes with n-alkyl chains was elucidated in their crystalline and liquid-crystalline states. In the former states, alternately stacked acceptor-acceptor assemblies caused fluorescence emission with eight percent quantum yield at maximum, while the donor-acceptor ones with less than one percent. Heat treatment yielded their liquid-crystalline assemblies comprising J-aggregation with yellow emissions. The emissions were red-shifted by about 20-40 nm as compared with those of their crystalline assemblies. Such temperature-dependent structural changes enable us to tune the emission colors.