Salen-type mononuclear dysprosium complex displays significant single-molecule magnet performance. Issue 10 (17th February 2022) - Wang, Luan
Abstract : The newly isolated salen-type mononuclear lanthanide complex [Dy(5-NO2 salcy)(NO3 )(CH3 OH)2 ] (1 ) reveals a uniquely high energy barrier of 64.94 K under zero dc field and a remarkable hysteresis loop at 6 K compared with known salen-type Dy-SIMs. Abstract : Three salen-type mononuclear lanthanide complexes with the general formula [Ln(5-NO2 salcy)(NO3 )(CH3 OH)2 ] (Ln = Dy (1 ), Ho (2 ) and Er (3 )) have been designed and synthesized by reactions of N, N ′-bis(5-nitrosalicylaldehyde)ethane-1, 2-cyclohexanediamine (5-NO2 salcyH2 ) with various lanthanide nitrates. Crystallographic analysis reveals that all three complexes 1–3 are of isomorphic mononuclear structures, in which Ln 3+ ions are eight-coordinated forming a near square antiprism geometry with D 4d symmetry. The alternating-current (ac) magnetic analysis reveals that complex 1 exhibits significant SMM performance with an energy barrier of 64.94 K and a surprising hysteresis temperature of up to 6 K under zero field, as well as an energy barrier of 157.78 K under optimized 1400 Oe. The study on its magnetism–structure relationship supports that the outstanding energy barrier and hysteresis temperature of complex 1 result from the high coordination symmetry and configuration of the oblate (axially elongated) electron cloud densities for the Kramers Dy 3+ ion. Notably, it has a remarkable performance compared with single-molecule magnets (SMMs) of numerous salen-type dysprosium complexes. This approach affords a strategy for preparing high performance salen-type dysprosium SMMs to further study their magnetism–structure relationship.