Octacyanidotungstate(IV) Coordination Chains Demonstrate a Light-Induced Excited Spin State Trapping Behavior and Magnetic Exchange Photoswitching

A huge increase in the magnetization of two coordination chains based on tetravalent octacyanidometalates (W-IV and Mo-IV) is observed on irradiation with 436nm light, while no such behavior is observed for the Nb-IV analogue. A photomagnetic response based solely on [W-IV(CN)(8)](4-) is demonstrated for the first time. The observed behavior is attributed to the light-induced excited spin state trapping (LIESST) effect at the octacyanidometalate, and to the resulting magnetic exchange ON/OFF photoswitching between the Mn-II center and the photoinduced high-spin (S=1) W-IV or Mo-IV centers.