Observation of two-step spin transition in iron(II) 4-amino-1,2,4-triazole based spin crossover nanoparticles.

A synthetically controllable two-step spin transition was observed in iron(II) spin crossover nanoparticles of the dehydrated one-dimensional coordination polymer [Fe(NH 2 trz) 3 ]Br 2 (NH 2 trz = 4-amino-1,2,4-triazole) using the reverse micellar method. The change from two-step to one-step hysteretic characteristics succeeded by changing the reaction time.