Various Sizes and Shapes of Mixed-Anion Fe(NH₂trz)₃(BF₄)_2−x(SiF₆)_x/2@SiO₂ Nanohybrid Particles Undergoing Spin Crossover Just Above Room Temperature

Abstract

Spin crossover (SCO) iron (II) coordination compounds in the form of nanohybrid SCO@SiO2 particles were prepared using a reverse micelles technique based on the TritonX-100/cyclohexane/water ternary system. Tetraethyl orthosilicate (TEOS) acts as precursor of both the SiF62− counter-anion and SiO2 to obtain Fe(NH2trz)3(BF4)2−x(SiF6)x/2@SiO2 nanoparticles with different sizes and morphologies while modifying the TEOS concentration and reaction time. The adjustable mixed-anion strategy leads to a range of quite scarce abrupt spin crossover behaviors with hysteresis just above room temperature (ca. 293 K), which is very promising for the integration of these materials into functional devices.

Keywords

• spin crossover
• iron(II)
• triazole
• reverse micelles
• nanoparticles