Photoreaction in two-component molecular crystals of α-hydroxycarboxylic acids and aza aromatic compounds

A series of two-component molecular crystals of α-hydroxycarboxylic acids such as benzilic acid (1) and S-(+)-mandelic acid (2) with aza aromatic compounds such as acridine (3), phenanthridine (4) and phenazine (5) were prepared by crystallization from the solutions of both components. Irradiation of the crystals caused photodecarboxylation and dehydrogenation to give benzophenone (6) or benzaldehyde (7) as a main product.