A difunctional Dy(III)-complex exhibiting single-molecule magnet behaviour and fluorescent cellular-imaging

Abstract

A mononuclear Dy(III) complex, with formula [Dy(Dicnq)(TFNB)3] (1), is synthesized through a self-assembly with 4,4,4-trifluoro-1-(2-naphthyl)-1,3-butanedione (TFNB) and 6,7-dicyanodipyrido [2,2-d:2′,3′-f] quinoxaline (Dicnq) ligands. Single-crystal structure determination reveals that Dy(III) ion in complex 1 features an N2O6 octacoordinated environment with distorted square-antiprism D4d geometry. Magnetic data analysis shows that 1 behaves as a single-molecule magnet, with an energy barrier of 192 K under zero dc field. With an external field of 1200 Oe, the quantum tunneling of magnetization is suppressed in 1, resulting in an enhanced energy barrier of 261 K. Additionally, 1 displays a room-temperature photoluminescence. Leveraging the optical properties coupled with minimal cytotoxic effects of 1, we assess its suitability for cellular imaging applications. Subsequent laser confocal microscopy analysis reveals that 1 is capable of efficiently traversing the plasma membrane and nuclear membrane of HeLa cells, an observation that is not commonly reported in dysprosium-based complexes.