Spontaneous chiral resolution of a MnIII spin crossover complex with high temperature 80 K hysteresis

Non-centrosymmetric spin switchable systems are of interest for their prospective applications as magnetically active non-linear optical materials and in multiferroic devices. Chiral resolution of simple spin crossover chelates complexes into the Δ and Λ forms offers a facile route to homochiral magnetic switches, which could be easily enantiomerically enriched. Here, we report the spontaneous resolution of new hysteretic spin crossover complex, [MnIII(sal2323)]SCN·EtOH (1), into Δ and Λ forms, without the use of chiral reagents, where sal2323 is the Schiff base resulting from condensation of 1,2-bis(3-aminopropylamino)ethane with 2-hydroxybenzaldehyde. The enantiopurity of the Δ and Λ isomers was confirmed by single crystal X-ray diffraction and circular dichroism, and quantum chemistry calculations were used to investigate the electronic structure. The opening of a wide 80 K thermal hysteresis window at high temperature highlights the potential for good magneto-optical function at ambient temperature for materials of this type.