Abstract

We report the reverse micelle synthesis, structural characterisation and magnetic properties of iron(iii) spin crossover (SCO) nanomaterials based on [Fe(qsal)<inf>2</inf>]NO<inf>3</inf>, [Fe(qsal-I)<inf>2</inf>]OTf and [Fe(qsal-I)<inf>2</inf>]NTf<inf>2</inf> using sodium dioctylsulfosuccinate (NaAOT) and hexane. The synthesis and characterization of a new complex, [Fe(qsal)<inf>2</inf>]NO<inf>3</inf>·EtOH is also reported. Systematic variation of micellar conditions including surfactant content in the polar and organic phases, reaction time, and solvent choice enabled the controlled formation of parallelogram, plate-like and rod-like shapes for [Fe(qsal)<inf>2</inf>]NO<inf>3</inf>, [Fe(qsal-I)<inf>2</inf>]OTf and [Fe(qsal-I)<inf>2</inf>]NTf<inf>2</inf>, respectively, as confirmed by FESEM. Magnetic studies reveal abrupt spin crossover with a narrower hysteresis width compared to the bulk materials. Nanomaterials of [Fe(qsal-I)<inf>2</inf>]OTf exhibit a 4 K hysteresis (T<inf>1/2</inf>↑ = 231 K and T<inf>1/2</inf>↓ = 227 K) while those of [Fe(qsal-I)<inf>2</inf>]NTf<inf>2</inf> display a 27 K hysteresis (T<inf>1/2</inf>↑ = 275 K and T<inf>1/2</inf>↓ = 248 K) comparable to the bulk. The results demonstrate that reverse micelle methods can reliably produce iron(iii) SCO nanomaterials, advancing their potential for integration into functional devices.