Circularly Polarized Luminescence From Spontaneous Symmetry Breaking in a Bimetallic Eu–Al Complex

The emergence of optically active functional compounds through spontaneous chiral symmetry breaking is a rare but intriguing phenomenon with relevance of both practical and fundamental interest. Here we show that a racemic Eu–Al compound, bearing only non-chiral ligands, forms a conglomerate upon crystallization. Single crystals of the compound are electronic circular dichroism (ECD) and circularly polarized luminescence (CPL) active. Moreover, we found that a significant enantiomeric excess (50%) of either enantiomer is present in each crystallization batch (non-racemic conglomerate). Such spontaneous symmetry breaking leads not only to optically active single enantiomorph crystals but to an overall solid bulk with significant ECD and CPL.