Modulation of the ligand-based fluorescence of 3d metal complexes upon spin state change

Two new Schiff base-like ligands bearing a heteroaromatic fluorophore were synthesised and converted into the corresponding Ni(II), Cu(II) and Zn(II) square planar complexes. The Ni(II) complexes were studied with regard to a coordination change-induced spin state change upon addition of pyridine in solution. An inverse correlation between the fluorescence properties and the spin state of the metal centre was observed, and investigated with steady state fluorescence and time-resolved spectroscopy.