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Metal–organic frameworks (MOFs) have become preferred heterogeneous catalytic materials for many reactions due to their advantages such as porosity and abundant active sites. Here, a 3D Mn-MOF-1 [Mn2(DPP)(H2O)3]·6H2O (DPP = 2,6-di(2,4-dicarboxyphenyl)-4-(pyridine-4-yl)pyridine) was successfully synthesized under solvothermal conditions. This Mn-MOF-1 possesses a 3D structure constructed by the combination of a 1D chain and the DPP4− ligand and features a micropore with a 1D drum-like shaped channel. Interestingly, Mn-MOF-1 can maintain the structure unchanged by the removal of coordinated and lattice water molecules, whose activated state (denoted as Mn-MOF-1a) contains rich Lewis acid sites (tetra- and pentacoordinated Mn2+ ions) and Lewis base sites (Npyridine atoms). Furthermore, Mn-MOF-1a shows excellent stability, which can be used to catalyze CO2 cycloaddition reactions efficiently under eco-friendly, solvent-free conditions. In addition, the synergistic effect of Mn-MOF-1a resulted in its promising potential in Knoevenagel condensation under ambient conditions. More importantly, the heterogeneous catalyst Mn-MOF-1a can be recycled and reused without an obvious decrease of activity for at least 5 reaction cycles. This work not only paves the way for the construction of Lewis acid–base bifunctional MOFs based on pyridyl-based polycarboxylate ligands but also demonstrates that Mn-based MOFs hold great promise as a heterogeneous catalyst toward both CO2 epoxidation and Knoevenagel condensation reactions. [ABSTRACT FROM AUTHOR]

A stable multifunctional Eu3+‐coordination polymer formulated as [Eu(Htzpia)(H2tzpia)]n (Eu‐CP‐1) has been successfully constructed by the reaction of Eu3+ ion with the new organic ligand 5‐(3‐(tetrazol‐5‐yl) phenyl) isophthalic acid (H3tzpia) under hydrothermal condition. Eu‐CP‐1 displays a 2D coordination network, in which 1D uniform chains with (μ‐COO)3 bridges are interlinked by the Htzpia and H2tzpia spacers. The 2D networks are associated into 3D architectures through hydrogen bonding interactions. Eu‐CP‐1 displays excellent luminescence property and exhibits good stability in water. Thus, Eu‐CP‐1 can be used to detect Fe3+ ions and MnO4− ions with high sensitivity and selectivity through luminescence quenching effect. Due to the presence of open metal sites, free oxygen/nitrogen atoms, and NH groups of tetrazole rings, Eu‐CP‐1 can act as an effective heterogeneous catalyst for the cycloaddition reaction of carbon dioxide with epoxides under eco‐friendly and solvent‐free conditions. Interestingly, Eu‐CP‐1 is highly recyclable and reusable for up to five cycles without an obvious loss in sensing or catalytic efficiency. In addition, the possible relevant mechanisms are also investigated. This work should aid in expanding potential application prospects of the lanthanide CPs in the fields of contaminated ions detection and CO2 cycloaddition. [ABSTRACT FROM AUTHOR]