Hierarchical Emergence and Dynamic Control of Chirality in a Photoresponsive Dinuclear Complex

Chiroptical
photoswitches are of interest from a viewpoint of applications
in advanced information technologies. We report dynamic on–off
photoswitching of circularly polarized luminescence (CPL) in a binuclear
europium complex system. Two coordination units are arranged closely
in a chiral fashion by a photoresponsive ligand with a one-handed
helical structure. The chirality in the helical scaffold is hierarchically
transferred to the chirality in nine-coordinate complex sites. The
chiral close arrangement of complex units induces the enrichment of
a specific chiral coordination structure in the nine-coordinate europium
sites. The chiral arrangement of complex units is switched in conjunction
with the photoinduced helix–nonhelix structural change in the
photoresponsive framework, demonstrating on–off switching of
CPL with high contrast.