Spin Crossover Materials

Fe(II) Spin Crossover

In our research group we are exploring Fe(II) and Fe(III) spin crossover systems with designed heterocyclic Schiff base ligands. We tune the electronic and steric properties of the ligand to access materials which show abrupt spin crossover close to room temperature.

In the case of Fe(II), the ligands we are exploring are based on imidazole and these complexes show spin crossover above, below and at room temperature. In switching from the HS to the LS state the complexes show a dramatic colour change from orange to deep red or purple. The reason for the change in colour is that the gap between t2g and eg* set is larger in the LS state.

Light harvesting Ru and Zn complexes

Fe(III) Spin Crossover

Iron(III) spin crossover complexes have the advantage of being air stable and are consequently easily developed into future materials. Using principles from crystal engineering we are exploring a new series of designed spin crossover compounds which exhibit abrupt and hysteretic spin crossover.

Structural studies of spin crossover compounds form an essential part of understanding how to design better spin crossover systems. In cases where the structural data of the complex before, during and after spin crossover are available it’s clear that large changes take place at the metal centre.