Spin State Modulation in Metallosupramolecular Iron(II) [2×2] Grids Triggered by Light, Heat, and Protonation effects

A series of [2x2] Iron(II) Grid-type complexes have been synthesized and characterized via Single-Crystal XRD experiments. The bis-hydrazone moiety inside the supramolecular frame has been designed to show spin-state switching of the metal centres by selective deprotonation of the N-H protons. The spin state switching behaviour has been experimentally shown in the solid as well as in the solution state with the help of solid-state magnetic measurement and paramagnetic 1H solution NMR. Diamagnetic Zn complexes have been synthesized and characterized to serve as a reference for the Iron complexes. We represent here the multi-stimuli responsive spin state switching behaviour in a series of Iron (II) Grids with varying ligand fields.