Synergetic spin crossover and fluorescence in a mononuclear iron(iii) complex

Two mononuclear iron(III) complexes (XEA)[Fe(azp)₂]·H₂O (H₂azp = 2,2'-azodiphenol, XEA = 2-fluoroethylammonium and 2-chloroethylammonium) are synthesized, which exhibit the counterion dependence of magnetic and fluorescent properties. The synergetic effect between abrupt spin crossover and fluorescence is observed in an iron(III) complex for the first time.