Switching of the Magnetocaloric Effect of MnII Glycolate by Water Molecules

The transformation of Mn-II glycolates (glc) between the three-dimensional coordination polymer [Mn(glc)(2)](n) (1) and discrete mononuclear phase [Mn(glc)(2)(H2O)(2)] (2) can be reversibly switched by water molecules, which dramatically change the magnetocaloric effect (MCE) of Mn-II glycolates from the maximum of 6.9Jkg(-1)K(-1) in 1 to 60.3Jkg(-1)K(-1) in 2. This case example reveals that the effect of magnetic coupling on MCE plays a dominant role over that of other factors such as magnetic density for 3d-type magnetic refrigerants.