Synthesis, Structure, and Optical‐response Magnetic Property of a Heteroarene‐azo Functionalized Mn₁₉ Cluster

Comprehensive Summary 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 [Mn II 15 Mn III 4 ( L ) 18 (OH) 12 (N 3 ) 6 ] (ClO 4 ) 2 (C 6 H 5 CN) 8 , ( Mn19azo , H L =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 CH 2 Cl 2 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.