In 2019, Boukheddaden and co-workers explored the interplay between luminescence and SCO in a multifunctional iron(II) complex . The iron complex along with an analogous copper(II) Single crystal X-ray diffraction studies at 296 and 100 K showed the presence of the iron center in the FeN6 surrounding, coordinated with six nitrogen donor atoms from the monodentate L4 ligand. At 296 K, the average Fe-N bond distance is 2.189(4) Å, indicating the HS state of Fe(II) in 5. Upon cooling down to 100 K, the average Fe-N bond distance reduces significantly to 1.995(4) Å, which lies in the expected range for the Fe(II) ion in the LS state. These observations suggest a thermo-induced SCO from HS to LS in 5 (Fig. ).