Reversible Photoswitching of a Spin‐Crossover Molecular Complex in the Solid State at Room Temperature

Abstract

Spin-crossover metal complexes are highly promising magnetic molecular switches for prospective molecule-based devices. The spin-crossover molecular photoswitches developed so far operate either at very low temperatures or in the liquid phase, which hinders practical applications. Herein, we present a molecular spin-crossover iron(II) complex that can be switched between paramagnetic high-spin and diamagnetic low-spin states with light at room temperature in the solid state. The reversible photoswitching is induced by alternating irradiation with ultraviolet and visible light and proceeds at the molecular level.

From Mononuclear to Dinuclear: Magnetic Properties of Transition Metal Complexes

“…We attempted the study but the preliminary results we have obtained were not as expected. Unfortunately, our insepctions fails, probably because of two factors: (i) the DFT/B3LYP* does not provide a correct ordering of the spin-states and situates the high-spin state as ground state, and (ii) the minimum active space needed to perform CASSCF/CASPT2 calculations is CAS (12,20) which is currently una↵ordable.…”

“…This is one of the reasons why more than twenty years after its discovery, LIESST e↵ect is still at the very center of the SCO research. The advances in short pulsed lasers enables researchers to extract information on the deactivation mechanism [15][16][17][18][19][20][21][22][23] and theoretical studies also contributed to the understanding of LIESST in octhedral Fe(II) complexes [60][61][62]. For Fe(III) complexes, the light irradiation induces ligand-tometal charge transfer transition (LMCT).…”

“…Therefore, the synthesis of systems with bistability under standard conditions for which switching is fast and both states are su ciently long-lived (i.e., persistent) has become increasingly important over the last 50 years. In this area of research, the interconversion between two di↵erent spin states that can be triggered by light irradiation is especially important [15][16][17][18][19][20][21][22][23]. The bistability in molecular magnets involves the M S components of a given spin state and the population of the bistable states can be controlled by the application of an external magnetic field.…”

A Neutral Fe4tBuL4 All Ferric Grid Complex: Structural and Variable Temperature Magnetic Properties

“…The design and synthesis of new molecular switching materials continues to garner much interest . With six‐coordinate transition metal complexes, molecular switching is typically found in d 4 ‐ d 7 metal ion systems in the form of spin‐crossover between high‐and‐low spin states, initiated by a change in temperature, application of external pressure or light irradiation .…”

Surface induces different crystal structures in a room temperature switchable spin crossover compound

“…[28][29][30][31][32][33] Since the switching conditions critically depend on the local molecular environment (e.g. packing, counter anions and/or solvent molecules, if included in the crystalline structures, etc.…”