Thermally tunable circular dichroism and circularly polarized luminescence of tetraphenylethene with two cholesterol pendants

Abstract

This work provides a novel strategy for the construction of materials exhibiting circularly polarized luminescence (CPL) with a thermal tunability and a high efficiency in the solid state. In this strategy, cholesterol pendants were introduced into tetraphenylethene, a typical aggregation-induced emission (AIE) molecule using long undecyl spacers as a covalent connection bridge. The resulting AIE molecule (2CTPE) exhibited CPL with a high dissymmetry factor (∼10⁻²) and a high fluorescence efficiency (42%) in the solid state. The presence of the long spacer led to the formation of a liquid crystal (LC) phase of 2CTPE with a typical focal conic texture of cholesteric LC, as revealed by polarizing optical microscopy (POM) investigation. Furthermore, circular dichroism (CD) and CPL properties of 2CTPE could be thermally regulated. These results give evidence to the synthesis of new, tunable CPL materials with a high fluorescence efficiency in the solid state.