Slow magnetic relaxation behavior of a {Dy2} complex based on a large n-conjugated bridging ligand

Binuclear lanthanide single molecule magnets (Ln-SMMs) based on large n-conjugated bridging ligands have shown potential in achieving excellent SMM performance. However, their members are still scarce until now. In this work, a novel binuclear Ln-SMM featuring a large n-conjugated bridging ligand, [Dy2(hfac)6(tpphz)]center dot CH2Cl2 (1), has been prepared. Its two DyIII centers are chelated and bridged by the large n-conjugated tetrapyrido[3,2-a:2 ',3 '-c:3 '',2 ''-h:2 ''',3 '''-j]phenazine (tpphz) ligand. Three 1,1,1,5,5,5-hexafluoroacetylacetonate (hfac-) ions acting as terminal ligands further complete the square antiprism coordination geometry of each DyIII center. Magnetic measurements revealed that 1 exhibits zero field SMM behavior with a single magnetic relaxation process. The effective energy barrier (Ueff) is 13.79 K. Interestingly, dual relaxation behavior including well -separated slow relaxation (SR) and fast relaxation (FR) processes was further observed when a dc field was applied. It could be ascribed to the different single ion anisotropy of the DyIII centers, as well as a possible contribution of magnetic interactions in the system of 1. The Ueff values for the SR and FR processes are 27.3 and 1.30 K, respectively.

Automated summary

In this work, a novel binuclear lanthanide single molecule magnet (Ln-SMM) with a large n-conjugated bridging ligand has been synthesized. Magnetic measurements showed that the compound exhibits a single magnetic relaxation process with an effective energy barrier of 13.79 K. Additionally, the application of a dc field revealed dual relaxation behavior, including well-separated slow and fast relaxation processes.