Photoinduced magnetic hysteresis in a cyanide-bridged two-dimensional [] coordination polymer

2D magnetic materials have been opening a new horizon in materials science. It is challenging to switch the magnetic hysteresis of 2D magnetic materials via light irradiation, which is applicable for future molecular devices. In this work, the reaction of (Bu 4 N) 3 [W V (CN) 8 ], MnCl 2 ·4H 2 O, and bis(4-pyridyl) disulfide (dpd) provides a new cyanide-bridged 2D compound, {[W IV (CN) 8 ][Mn II (dpd) 2 ][Mn II (CH 3 OH) 2 ]·2CH 3 OH·2H 2 O} n ([ Mn 2 W LS ] and LS: low spin). The magnetic susceptibility measurements of [ Mn 2 W LS ] suggest that paramagnetic Mn II ( S = 5/2) ions are magnetically separated by diamagnetic W IV ions. Photomagnetic experiments using a 405 nm laser confirm the presence of the light-induced excited spin state trapping (LIESST) effect on the W IV ions from the singlet ( S = 0) to the triplet ( S = 1) states, and the formation of a metastable high spin species, [ Mn 2 W HS ]. In this photogenerated metastable phase, the W IV ( S = 1) and Mn II ( S = 5/2) ions are antiferromagnetically coupled. Field-cooled magnetization experiments suggest that the photoinduced [ Mn 2 W HS ] layer compound is a ferrimagnet with a transition temperature of 24 K. The current work provides a strategy to build photoswitchable 2D magnetic materials. A 2D coordination polymer [ Mn 2 W ] underwent photoinduced singlet ( S = 0) to triplet ( S = 1) transition on the W IV ions, resulting in magnetic ordering with a transition temperature of 24 K and a hysteresis loop up to 15 K.