Luminescence thermometry in a Dy 4 single molecule magnet.

The tetranuclear linear complex [Dy 4 (1,1,4-H 3 L r ) 2 (OAc) 6 ]·CH 3 OH (1·CH 3 OH) was satisfactorily prepared and characterized. Its X-ray structure shows that it contains two types of octacoordinated Dy III ions, with distorted triangular dodecahedral and square antiprism geometries. This complex is an SMM, with multiple relaxation pathways, and with an anisotropic energy barrier of 39.7 K. 1·CH 3 OH also operates as a luminescent thermometer in the 11-295 K range, with a maximum relative thermal sensitivity of 1.6% K -1 and a minimum temperature uncertainty of 1.1 K at 295 K. Thus, 1·CH 3 OH is the first Dy 4 SMM with luminescent thermometry, and this system is a rare example of dysprosium SMM that accesses the thermometric characteristics involving the ligand ascribed to the triplet emission in combination with Dy III emission.