Spiropyran-based multi-colored switching tuned by pressure and mechanical grinding

Abstract

The novel multi-colored switching mechanochromic materials were obtained based on a spiropyran and pyrene derivative. The mechanochromic behaviors under either isotropic compression or anisotropic grinding were realized through a combination of supramolecular and chemical structural changes. The high pressure achieved by utilizing the Diamond Anvil Cell technique induced a continuous mechanochromic process involving a color change from blue to red, while the tricolored switching could be achieved by sequential light or heavy grinding of the sample powder. The mechanochromic behaviors could be adjusted via the control of the modes and strength of the mechanical loadings. This molecule showcases a novel straightforward strategy for the design of multi-colored switching molecules and the control of mechanochromism under pressure based on both supramolecular changes and molecular structural changes. It shows great potential for applications in pressure sensors, pressure calibration, mechanoprobes and security inks.