Bifunctional Lanthanide MOFs with Phosphorus Ligands: Selective Luminescent Detection of Borides and CO₂ Conversion

There is an increasing demand for the development of lanthanide metal-organic frameworks and derived multifunctional materials. The functional properties of such compounds are influenced by the arrangement of various Lewis basic sites or structural configurations of the ligands. In this study, a series of isostructural Ln-MOFs containing a phosphine-dicarboxylate ligand, [Ln(HL)(L)(DMF)]·DMF (where H₂L = 5-(diphenylphosphanyl)isophthalic acid, Ln = Tb³⁺ (1), Eu³⁺ (2), Gd³⁺ (3), Ce³⁺ (4), and Nd³⁺ (5)), was synthesized under solvothermal conditions and characterized in detail. Among the obtained compounds, Tb-MOF 1 demonstrated excellent luminescent properties with a high quantum yield (90.45%) and considerable lifetime (1266 μs). Furthermore, 1 acts as a unique luminescent Ln sensor for 4-formylphenylboronic acid and 9-[3-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)phenyl]carbazole, exhibiting low detection limits of 1.38 and 3.62 mM, respectively. Additionally, Nd-MOF 5 acts as an efficient catalyst for coupling carbon dioxide to epoxy compounds, resulting in high conversion rates (up to 96%). This study further extends the growing family of Ln-MOFs and provides insights for preparing multifunctional materials through the modification of organic ligands with specific functional groups.