Bifunctional Hybrid SiO₂ Nanoparticles Showing Synergy between Core Spin Crossover and Shell Luminescence Properties

Let there be light: Hybrid SiO2 nanoparticles with a spin-crossover polymer core and a luminescent shell have been synthesized (see picture). These nanomaterials exhibit a thermally induced low-spin (LS) → high-spin (HS) transition that is accompanied by a drastic color change. This optical bistability tunes the luminescence properties of the fluorophores grafted on the surface of the materials.