Synthesis, Structure, and Optical-response Magnetic Property of a Heteroarene-azo Functionalized Mn-19 Cluster

Metal clusters with photoswitching ligands can undergo magnetic changes under light radiation, which makes them potential optical-response magnetic-switching materials. Herein, a photoswitchable Mn-oxo cluster [(Mn15Mn4III)-Mn-II(L)(18)(OH)(12)(N-3)(6)] (ClO4)(2) (C6H5CN)(8), (Mn19azo, HL=1-(hydroxymethyl)-3,5-dimethyl-4-(phenyldiazenyl)-pyrazole) has been designed and synthesized to realize the photoswitching behavior. Mn19azo shows quick trans-to-cis transformation upon 365 nm light irradiation in CH2Cl2 solution and solid state as confirmed by UV-Vis spectra. After the powder sample was irradiated for 80 min, the Curie constant of Mn19azo increases by about 7%. The change of magnetic properties can be considered as the result of the change of intermolecular interactions.