Study of strong cooperative spin-crossover mononuclear complexes using high-resolution X-ray powder diffraction

We are looking to perform an extensive structural study on a new class of Fe(II) mononuclear complexes showing a first-order spin transition with unconventional large thermal hysteresis expanding around room temperature. We have previously demonstrated the possibility of a hysteresis loop modulation upon thermal-induced phase transition in this family of compounds, where a rearrangement of a flexible methoxy functional group occurs. In this work, much more rigid chemical functions R are appended in the ligand, so we expected that the origin of cooperativity its due to important structural distortions upon reversible conversion between both spin states, where the appearance of symmetry breaking can play a fundamental role. These new molecular platforms can be chemically modified in a simple way, and thereby subtly modulate their SCO behaviour and thus their barocaloric properties, which is essential for future applications in eco-friendly technologies.