In this paper, we report on the synthesis, crystal structure, and photomagnetic properties of the spin-crossover salt of formula [Fe(bpp)2](C6H4NO2)2·4H2O (1·4H2O) (bpp = 2,6-bis(pyrazol-3-yl)pyridine; C6H4NO2− = nicotinate anion). This compound exhibits a 3D supramolecular architecture built from hydrogen bonds between iron(II) complexes, nicotinate anions, and water molecules. As synthesized, the hydrated material is low-spin and desolvation triggers a low-spin (LS) to high-spin (HS) transformation. Anhydrous phase 1 undergoes a partial spin crossover (T1/2= 281 K) and a LS to HS photomagnetic conversion with a T(LIESST) value of 56 K.
A new tetradentate Schiff base-like ligand H2L (1) ((E,E)-dimethyl-2,2´-[1,2-phenylenebis(aminomethylidyne)] bis[3-oxobutanoate]) was synthesised and structurally characterised. Its reaction with iron(II) acetate leads to the formation of the octahedral N2O4-coordinated complex [FeL(MeOH)2] (2). The complex is a pure high-spin (HS) compound as is evident from magnetic measurements and X-ray crystallography.
Bifunctional fluorescent spin crossover complexes exhibit thermally and light induced conversion from the low spin to the high spin state, as well as fluorescence emission.
Synthesis, Structure, and Photomagnetic Properties of a Hydrogen-Bonded Lattice of [Fe(bpp)2]2+ Spin-Crossover Complexes and Nicotinate Anions