Synthesis and Characterization of [Fe(Htrz) 2 (trz)](BF 4 )] Nanocubes.

Compounds that exhibit spin-crossover (SCO) type behavior have been extensively investigated due to their ability to act as molecular switches. Depending on the coordinating ligand, in this case 1H -1,2,4-triazole, and the crystallite size of the SCO compound produced, the energy requirement for the spin state transition can vary. Here, SCO [Fe(Htrz) ₂ (trz)](BF ₄ )] nanoparticles were synthesized using modified reverse micelle methods. Reaction conditions and reagent ratios are strictly controlled to produce nanocubes of 40-50 nm in size. Decreases in energy requirements are seen in both thermal and magnetic transitions for the smaller sized crystallites, where, compared to bulk materials, a decrease of as much as 20 °C can be seen in low to high spin state transitions.