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High sensitivity and selectivity for the detection of metal ions are very important to protect human health. Fluorescent metal–organic frameworks (MOFs) as new sensing materials have attracted more and more attention. Herein, a pillar-layered fluorescent metal–organic framework, {[H2N(CH3)2]2[Cd5(TCPE)3(4,4′-bpy)2(MeOH)2(H2O)4]}n (NKM-102) (H4TCPE = tetrakis(4-carboxyphenyl)ethylene acids, 4,4′-bpy = 4,4′-bipyridine), has been synthesized through utilization of the H4TCPE ligand with typical AIE characteristics. NKM-102 exhibits excellent fluorescence emission performance and detects Al3+ ions with high selectivity through turn-off effect and emission color change. Moreover, the detection limit of NKM-102 can reach 158 ppb, which is lower than the maximum limit of Al3+ ions in drinking water recommended by the United States Environmental Protection Agency (200 ppb). Therefore, the NKM-102 probe is a prominent candidate for the visual detection of Al3+ ions with high sensitivity and selectivity. [ABSTRACT FROM AUTHOR]

In our continuous efforts to explore the effects of metal ions, ligands and counter anions on the structures and properties of metal–organic complexes, six transitional metal complexes with two structurally related ligands, 1,4-bis(1,2,4-triazol-1-ylmethyl)naphthalene (L1) and 4,4′-bis(1,2,4-triazol-1-ylmethyl)biphenyl (L2), [Cd(L1)2(NO3)2(H2O)]∞(1), [Hg(L1)0.5(Br)2] (2), {[Mn(L1)2Cl2](H2O)8}∞(3), {[Cu(L1)2Cl2](H2O)8}∞(4), {[Cd(L2)2(CH3OH)2(NO3)2](H2O)}∞(5) and [Cd(L2)3(CH3OH)2(ClO4)2(CHCl3)]∞(6), were synthesized and structurally characterized. 1has an infinite two-dimensional (2D) network structure and the 2D network further assembled into a 3D interpenetrating structure, 2is a dinuclear structural molecule, 3and 4are neutral molecules with 1D chain structures and the same packing modes, and 5and 6have a similar structure, consisting of a 1D neutral coordination chain, but the coordination geometry around the CdIIion in 6is different from that in 5. The results indicated that the structural differences among them are attributable to the difference of metal ions, counter-anions and ligands frameworks. All the complexes are air stable at room temperature. L1and L2adopt trans–gaucheas well as gauche–gaucheconformation with the shortest NN distance between the two donors in all complexes. Furthermore, the fluorescent properties of complexes 1, 5, 6and all ligands have been investigated and discussed. [ABSTRACT FROM AUTHOR]