The interaction between the spin transition and a crystallographic phase transition in the spin-crossover compound [Fe(bbtr)3](ClO4)2: Nucleation, formation of domains and fluctuations

The thermal and the light-induced spin transition in [Fe(bbtr)3](ClO4)2 (bbtr = 1,4-di(1,2,3-triazol-1-yl)) as well as the high-spin → low-spin relaxation following the light-induced population of the high-spin state below the thermal transition temperature are discussed in relation to the accompanying crystallographic phase transition. The experimental data have exclusively been obtained using optical single crystal absorption spectroscopy.

The graphical abstract shows relaxation curves around transition temperature for a [Fe(bbtr)3](ClO4)2 small high-quality crystal. While at 101 K the relaxation curves are single exponential and smooth, at higher temperatures they show distinct steps, with the same height for different relaxation curves that is in line with a memory effect.Figure optionsDownload as PowerPoint slide