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

Two mononuclear iron(III) complexes (XEA)[Fe(azp)]·HO (Hazp = 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.

Hysteretic four-step spin-crossover in a 3D Hofmann-type metal-organic framework with aromatic guest.

A new Hofmann-type metal-organic framework with bent pillar ligand, [Fe(dpoda){Ag(CN)}] (dpoda = 2,5-di-(pyridyl)-1,3,4-oxadiazole), was synthesized. Four-, two- and one-step spin-crossover (SCO) properties were obtained by using different sizes of aromatic guests. Most importantly, hysteretic four-step SCO behaviour with the sequence of LS ↔ HSLS↔ HSLS↔ HSLS↔ HS is observed for the first time.