Softening and Hardening of Macro- and Nano-Sized Organic Cocrystals in a Single-Crystal Transformation


  • C.K., L.R.D., and A.V.T. gratefully acknowledge financial support from the University of Iowa. D.K.B, T.F., and L.R.M acknowledge the National Science Foundation (DMR-0133138) for partial support.


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AFM nanoindentation was used to demonstrate that millimeter- and nanometer-sized organic cocrystals exhibit changes in the mechanical properties before, during, and after a single-crystal-to-single-crystal [2+2] photodimerization of olefins. Millimeter-sized crystals become 40 % softer, whereas nanocrystals of the same material become 40 % harder following the photoreaction.