Two New Coordination Polymers: Crystal Structures and Fluorescence Properties

A new Ni (II) metal-organic frameworks with the formula [Ni₂(HL)₂(H₂O)₄]∙3H₂O (1) and a novel phenoxo-O bridged rare-earth dinuclear Schiff base complex with the formula [La₂(dbm)₄L·CH₃OH] (2), where the HL^2- is the partial deprotonated of the organic ligand H₃L, and H₂L is a bis-Schiff foundation ligand (H₃L = 4,6-dioxo-1,4,5,6-tetrahydro-1,3,5-triazine-2-carboxylic acid, H₂L = N, N'-bis (2-hydroxy-3-methoxybenzylidene) -propane-1,2-diamine, Hdbm = dibenzoylmethane), have been successfully generated under the solvothermal condition. The targeted product sample of 1 and 2 has been fully characterized by single-crystal X-ray data, elemental analysis, FT-IR, powder X-ray diffraction, and thermogravimetric analysis. Furthermore, fluorescence performance testing of the complexes revealed that in complex 1, H₃L forms a rigid chain through coordination with Ni²⁺ ions and further forms a highly rigid three-dimensional framework within the hydrogen bond network, resulting in fluorescence enhancement of up to 13.7-fold, displaying deep blue fluorescence with CIE coordinates of (0.1626, 0.1375). In contrast, complex 2 forms only discrete zero-dimensional molecules and exhibits light blue fluorescence with CIE coordinates of (0.1744, 0.2306). This demonstrates their potential as fluorescent materials.