Atmospheric humidity-triggered reversible spin-state switching

Abstract

The practical application of molecular switches is highly dependent on the reversible spin-state switching under ambient conditions, which needs a delicate materials design. Here, by confining a spin-crossover material into a sponge, the challenging goal of reversible spin-state switching in the solid state under ambient conditions has been realized, upon irradiation with a 980 nm laser for 120 s followed by shutting off the laser for 150 s. More importantly, further integration of the hygroscopic material has endowed the sponge with the merits of effective atmospheric humidity-triggered reversible spin-state switching under ambient conditions for the first time, accompanied by a reversible color variation upon naturally occurring humidity capture/release cycles. This work is expected to provide a fairly good strategy for developing novel molecular switches triggered by natural energy sources at the device level.