Long-Duration Crystal-Jumping by a Stepwise Stimulation: Thermal Induction of Strain and Its Release by Spontaneous Desolvation

Abstract

Abstract Here we report thermally-induced and long-duration jumping phenomena in a toluene-solvated crystal of zinc(II) tetraphenylporphyrin. The crystal splits into pieces along with a jumping phenomenon by cooling after heating over its desolvation temperature. Interestingly, the jumping phenomenon was observed for more than a few minutes after the thermal stimulus. Microscope observations, thermal analyses, and X-ray crystallographic studies revealed that the long-duration jumping phenomenon is due to a stepwise stimulation: accumulation of thermally-induced strain by coexisting the solvated and unsolvated crystal structures, i.e. pseudo-polymorphs, in the crystal and release of the strain triggered by time, i.e. gradual spontaneous desolvation at the ambient conditions. Our findings based on the stepwise approach demonstrate that time can work as a stimulus for jumping molecular crystals and demonstrate their designability by introduction of strain as an artificial modification.