Photodimerization of Anthracenes in the Solid State: New Results from Atomic Force Microscopy

The phase changes for topochemically allowed and forbidden photodimerizations of crystalline anthracene derivatives [Eq. (a)] become visible under the atomic force microscope. In all cases, surprisingly, the formation of surfaces resembling ice floes is observed, accompanied by considerable material transport. No processes with minimal atomic and molecular movement are seen. The new phase formation must therefore be included in the reaction description from the beginning. R = H, CH3, Cl, CN.