Four Dinuclear and One-Dimensional-Chain Dysprosium and Terbium Complexes Based on 2‑Hydroxy-3-methoxybenzoic Acid: Structures, Fluorescence, Single-Molecule-Magnet, and Ab Initio Investigation

The unique electronic configurations of lanthanide­(III) ions generate abundant electronic energy levels, resulting in the fantastic magnetic and optical multifunctional properties of lanthanide complexes. Here, 2-hydroxy-3-methoxybenzoic acid (H₂MBA) was used to construct four Dy­(III) and Tb­(III) complexes containing two isostructural dinuclear complexes of [Ln₂(HMBA)₂(MBA)₂(DMF)₂(H₂O)₂]·6H₂O [Ln = Dy (1), Tb (2); DMF = N,N-dimethylformamide] and two other isostructural beltlike one-dimensional-chain complexes of [NH₄]­[Ln­(HMBA)₄] [Ln = Dy (3), Tb (4)]. Fluorescence measurements reveal that H₂MBA can sensitize Dy­(III) and Tb­(III) characteristic luminescence. Furthermore, complex 3 can emit white light under UV-light irradiation originating from a dichromatic mixture of a blue emission of H₂MBA and a dominating yellow emission of Dy³⁺ ions. Magnetic susceptibility measurements show that two Dy­(III) complexes are single-molecule magnets with anisotropy barriers of 90(2) and 31(5) cm^–1 for 1 and 3, respectively. The magnet–luminescence–structure correlations as well as relaxation pathways are investigated by ab initio calculations and fluorescent spectrometry.