Tuning Magnetic Anisotropy and Luminescence Thermometry in a Series of Dysprosium Complexes containing β-diimine Ligand

Understanding spin dynamics in molecular systems is critical for developing advanced quantum materials, where optimizing structural parameters plays a pivotal role. Although significant progress has been made in studying the spin dynamics of β-diketone-Dysprosium(III) complexes with α-diimine bidentate ligands, the exploration of β-diimine-based ligands to elucidate the structure-property relationship in spin dynamics remains limited. Here, we report three Dysprosium complexes containing -diimine based bidentate ligands, [Dy(dbm)3(bik-Et)] (1), [Dy(dbm)3(bik-Me)] (2), and [Dy(acac)3(bik-Et)] (3) (dbm = 1,3-diphenyl-1,3-propanedione, acac = acetylacetonate, bik-Et = bis(1-ethyl-1H-imidazol-2-yl)methanone), and bik-Me = bis(1-methyl-1H-imidazol-2-yl)methanone)), which were synthesized and characterized by single crystal X-ray diffraction analysis, spectroscopic, magnetic and theoretical investigations. Structural investigations showed a distorted square antiprism geometry in 1 and 3 and a trigonal bipyramidal geometry in 2 in a DyO6N2 environment. Magnetic studies reveal slow magnetic relaxation behaviour under a zero-applied DC field for all three complexes. Theoretical calculations at the DFT and CASSCF level of theory were carried out to find a better correlation between the electronic structure and magnetism of the reported complexes. Moreover, the variable temperature photoluminescence study of the complexes reveals these complexes performed significantly well in the application of luminescent thermometry.