Synthesis and Chiroptical Properties of Cyclic Anthraquinodimethane Dimer Using Au-Templated Method

Cyclic anthraquinodimethane (AQD) dimer with a highly constrained structure was synthesized by using the Au-templated method. X-ray diffraction analysis and UV-Vis spectroscopy revealed that the AQD skeleton adopts a deeply folded structure and exhibits red-shifted absorptions in the dimer compared to those in non-cyclized monomeric AQD. Due to the rigid and constrained structure, both enantiomers of the cyclic AQD dimer with planar chirality can be isolated and show strong circular dichroism signals. It is demonstrated that the Au-templated method is a valuable way to access a highly constrained cyclic structure with AQD skeletons.