Two mononuclear chromophore coumarin-based Dy(III) complexes with magnetic relaxation and luminescent properties

Lanthanide luminescent single-molecule magnets (SMMs) serve as a kind of multifunctional molecular materials that have attracted extensive attention. Herein, a novel chromophore coumarin ligand 7-(diethylamino)-(2‑hydroxy-3-methoxybenzylidene)-2-oxo-2-chromene-3-carbohydrazide (Hvalcoumarin) is designed to construct the luminescent Dy(III) complexes. Two Dy complexes 1 ([Dy(valcoumarin)(DMF)2Cl2]·(CHCl3)) and 2 [Dy(valcoumarin)(DMF)2(NO3)2] were synthesized based on the luminescent chromophore coumarin ligand (Hvalcoumarin). X-ray crystallography reveals that the Dy(III) center in complex 1 adopts a hepta-coordinated arrangement by a distorted pentagonal bipyramidal geometry. In contrast, complex 2 exhibits a nine-coordinate arrangement by a spherical capped square antiprism geometry. Magnetic investigations reveal that 1 and 2 exhibit a slow magnetic relaxation phenomenon. Furthermore, the luminescent spectra of 1 and 2 display the characteristic emission profiles associated with Dy(III) spectra. Moreover, theoretical calculations also demonstrated the relaxation dynamics of 1 and 2. The results furnish a potent avenue for the acquisition of multifunctional molecular materials with magnetic and luminescent properties.