Employing Lanthanide Carbonates as Alkalinity Regulator and Metal Ion Sustained‐Release Source for Direct and Green Synthesis of Crystalline Carboxylate Complexes and Luminescence Property Modulation

Following more direct and environmentally friendly synthetic principles, this work demonstrates the successful application of lanthanide carbonates as alkalinity regulator and metal ion sustained‐release source for the synthesis of three series of pure crystalline lanthanide complexes [Ln 2 (μ‐cbc) 4 (cbc) 2 (phen) 2 ] ( CP‐Ln ), [Ln 2 (μ‐ns) 2 (Hns) 2 (phen) 2 (H 2 O) 2 ] ( 5P‐Ln ), and [Ln 2 (μ‐dns) 3 (phen) 2 (H 2 O) 3 ] n ( 35P‐Eu ) (Ln = Eu 3+ , Tb 3+ and Dy 3+ ; Hcbc = cyclobutanecarboxylic acid; H 2 ns = 5‐nitrosalicylic acid; H 2 dns = 3,5‐dinitrosalicylic acid; phen = 1,10‐phenanthroline). All of them were synthesized for the first time and structurally characterized by single‐crystal X‐ray diffraction. This lanthanide carbonate method yielded high‐quality single crystals in situ efficiently, avoiding anion pollution and aligning with green chemistry principles. Apart from the ligand‐sensitized photoluminescence for the lanthanide ions, CP‐Dy exhibited single‐molecule cold white‐light emitter in lightning applications. Furthermore, 5P‐Eu can be used as a potentially exceptional “monochromatic” emitter related to highly pure color for red. Notably, by leveraging the strong electron‐withdrawing effect of the nitro groups to tailor the intra ‐ligand charge transfer state efficiently, 35P‐Eu provided an intense red luminophore with a broad excitation band extending into the visible region. This study not only establishes the lanthanide carbonate method as a robust synthetic strategy but also provides insights into tuning luminescence properties through rational ligand design for potential applications in long‐wavelength excitation sources.