Spin-crossover tuning of the luminescence in 2D Hofmann-type compounds in bulk and exfoliated flakes

Abstract

Two Hofmann-type multifunctional materials are reported, displaying a tuning of the luminescence properties by the spin-crossover, and have exfoliated by in nanometric flakes by the Scotch-tape method.

Optical Phenomena in Molecule-Based Magnetic Materials

“…As a result, the SCO-active Fe­(II) complexes are not only broadly achievable but also reveal the most pronounced switching of numerous physical properties, including magnetic and optical, as well as mechanical or dielectric ones; thus, the related switching effects are still under intensive investigation. ,− In the context of designing materials based on the SCO systems, an enormous development has been observed in the recent decade when many different types of molecular systems from this family were successfully transferred into functional nanomaterials. , Although in most cases upon the formation of nanomaterials, bulk properties of the system are modified, the most crucial point lies in the preservation of its integrity and related SCO-activity. Among successful strategies, one may list the synthesis of SCO nanoparticles, core-shell heterostructures, thin film nanocrystalline phases, or even molecule-based monolayers. − Moreover, when deposited on the surface, the SCO-active systems can modify the properties of the substrate upon the occurrence of the spin transition stimulated by the change of temperature, irradiation, and other factors, while the output is registered in the form of electrical or optical response. − When combining two magnetic phases into heterostructures, the impact of SCO occurring in the first component upon the properties of the second was noticed . Generalizing to some extent, from the point of the application horizon, the materials showing the near-room-temperature spin crossover effect are the most suitable for sensing, including temperature sensing in solution, sensing of solvent vapors and gases, or mechanical strain sensing in the solid phase. − Then the related spin transition may or even should occur within a low-cooperativity process, to observe rather gradual changes within the optical absorption or the emission in the case of luminescent SCO materials.…”