Luminescence thermometry in a Dy4 single molecule magnet

Abstract

The tetranuclear linear complex [Dy₄(1,1,4-H₃L^r)₂(OAc)₆]·CH₃OH (1·CH₃OH) 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·CH₃OH 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·CH₃OH is the first Dy₄ 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.