Absolute configuration determination of the anti-head-to-head photo­cyclo­dimer of anthracene-2-carb­oxy­lic acid through cocrystallization with L-prolinol

The absolute configuration of the enantio­pure anti-head-to-head cyclo­dimer of anthracene-2-carb­oxy­lic acid was determined. The dimer inter­acts with L-prolinol through a nine-membered hydrogen-bonded ring [(9)], while a di­chloro­methane mol­ecule is incorporated to fill the void space.