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The two functional fluorinated ligands 2-fluoro-4-(1H-tetrazol-5-yl)benzoic acid (2-F-H2tzba) and 3-fluoro-4-(1H-tetrazol-5-yl)benzoic acid (3-F-H2tzba) were obtained by modifying 4-(1H-tetrazol-5-...

Four isostructural lanthanide metal–organic frameworks (Ln-MOFs) {[Ln(L)1.5(H2O)]·4H2O}n (1-Ln) (Ln = Sm, Eu, Gd, and Tb) have been successfully synthesized under solvothermal conditions with 2-(1H-1,2,4-triazol-1-yl) terephthalic acid (H2L) and Ln(NO3)3·nH2O (n = 0, 6). 1-Ln shows a binodal (3,8)-connected three-dimensional framework that possesses a one-dimensional pore channel decorated with uncoordinated Lewis basic triazolyl sites. 1-Eu and 1-Tb exhibit bright red and green emissions with absolute quantum yields of 9.1% for 1-Eu and 53.3% for 1-Tb. The luminescence explorations demonstrated that 1-Tb exhibits high quenching efficiency and low detection limit for sensing Fe3+ and nitrobenzene. Meanwhile, the fluorescence intensity of the quenched 1-Tb samples was resumed after washing with ethanol, which shows highly selective and recyclable luminescence sensing for Fe3+ and nitrobenzene. Importantly, by doping different concentrations of Eu3+ and Tb3+ ions, a series of dichromatic doped 1-EuxTb1-x MO...

Employing a V-shaped rigid multicarboxylate ligand 1,3-di(2′,5′-dicarboxypheny)benzene acid (H4L), three microporous metal–organic frameworks (MOFs), H2[Co4(O)L2(H2O)2]·3DMA·8H2O (1), H3[Zn2.5L2]·NMP·5H2O (2), and H3[Cd2.5L2]·4DMF·3H2O (3) were synthesized and characterized. Compound 1 exhibits a cage-based (3,6)-connected rtl topological MOF with [Co4O(COO)8] clusters and highly selective adsorption of CO2 over CH4. Compounds 2 and 3 are isostructural and display a rare 4,8-connected flu net with linear trinuclear [Zn3(COO)6] clusters. Interestingly, when compound 3 was soaked in DMF solution containing Eu3+ ions, an Eu-loaded compound Eu@3 with bright red fluorescence was obtained, which reveals highly selective sensing for Cu2+, Fe3+, and Cr2O72– ions. This represents an unusual example to achieve the detection of Cu2+, Fe3+, and Cr2O72– ions simultaneously by fluorescence spectrometry based on a recyclable Eu-loaded MOF sensor.

Three isostructural lanthanide metal–organic frameworks (Ln-MOFs), {[Ln2(BDPO)1.5(DMA)3(H2O)]·5H2O }n (1-Ln, Ln = Eu, Gd, and Tb) were constructed by a less-investigated large delocalized π-electron conjugated ligand N,N′-bis(3,5-dicarboxyphenyl)-oxalamide (H4BDPO). 1-Ln reveals unprecedented trinodal (4,4,6)-connected networks based on binuclear cluster units and planar BDPO linkers. Density functional theory (DFT) and time dependent-DFT calculations were performed on the ground and excited states to provide insight into geometries, the frontier molecular orbitals, and singlet and triplet state energies of H4BDPO ligand. 1-Eu and 1-Tb exhibit strong typical red and green emission of Eu3+ and Tb3+ ions, respectively, originating from the highly efficient energy transfer from BDPO to metal centers, as demonstrated by the comparison of triplet excited energies of ligands and metal ions. Importantly, by doping different concentrations of Eu3+ and Tb3+ ions, a series of dichromatic doped 1-EuxTb1-x MOFs were ...

Five new Cd(II) complexes, {[Cd1.5(tzia)(H2O)2]·H2O}n (1), {[Cd1.5(tzia)(H2O)4]·1.5H2O}n (2), [Cd(H2tzia)2(H2O)4]·H2O (3), [Cd5(μ3-OH)(tzia)3(H2O)7]·2H2O}n (4), and {[Cd2(μ3-OH)(tzia)(H2O)2]·H2O}n (5) (H3tzia = 5-(1H-tetrazol-5-yl)isophthalic acid), were assembled employing a tetrazolyl-carboxyl ligand H3tzia with Cd(II) ions, revealing versatile structures from zero-dimensional (0D) mononuclear molecule, 2D layer to 3D framework, in which five new types of coordination modes of H3tzia were observed. Complex 1 shows a 3D (3,6)-connected ant net based on trinuclear [Cd3(COO)2(N4C)2] cluster; 2 forms an unusual 3D (3,4)-connected 3,4T1 net with 1D tubes based on the 26-membered metallocycles; 3 is a mononuclear molecule; 4 displays an unprecedented (3,4,10)-connected 2D layer based on pentanuclear [Cd5(μ3-OH)(COO)2(N4C)3] cluster; 5 is a 3D porous framework containing 1D Cd-hydroxy-tetrazolyl ribbons. Complexes 1–5 exhibit strong luminescence with different energies resulted from the various coordination mo...

Under solvothermal conditions, six new Zn(II) coordination polymers, [(CH3)2NH2]2[Zn(L)]·2H2O (1), [Zn2(L)(py)2] (2), [Zn2(L)(bpe)2]·bpe·6H2O (3), [Zn2(L)(bpe)(DMA)(H2O)]·5H2O (4), [Zn2(L)(bpy)0.5(H2O)2]·2.5H2O (5), and [Zn2(L)(bpe)(H2O)]·3H2O (6) [H4L = 5,5′-(p-xylylenediamino)-1,1′,3,3′-(benzenetetra-carboxylic acid), py = pyridine, bpy = 4,4′-dipyridine and bpe = 1,2-bis(4-pyridyl)ethane], have been synthesized by employing a flexible tetracarboxylic acid H4L and different auxiliary pyridine-based ligands. In 1–6, all L4– ligands are 4-connected nodes; however, the diverse configurations of the two terminal isophthalate units of L4– around the central −NHCH2PhCH2NH– spacer lead to various topological nets. 1 shows a three-dimensional (3D) 2-fold interpenetrated 4-connected dia network resulting from the vertical configuration of the two isophthalate units of L4–. 2 displays a 3D (4,4)-connected pts net in which the two isophthalate units of L4– adopt a parallel configuration. The two isophthalate units...

By reacting a tritopic ligand 5-(4-carboxyphenyl)nicotinic acid (H2cpna) with Co(NO3)2 under different conditions, two new three-dimensional (3D) frameworks, [Co2(cpna)2(H2O)3]·DMF·9(H2O) (1) and [Co4(cpna)4(H2O)8] (2), have been obtained. They exhibit (3,6)-connected topological nets based on Co2 clusters and Y-shaped trinodal cpna2– linkers. 1 presents a chiral anh net with the right-handed helical channels, while 2 shows an achiral framework with a rtl topology. The whole structures of 1 and 2 are constructed from 2D achiral layers interconnected by triangular cpna2– nodes. Notably, these layers contain two heterochiral vertical and parallel 21 helical chains for 1 and 2, respectively, and those chains are constructed with 4-connected tetrahedral or square planar centers in their respective layers. The magnetic studies indicate that 1 and 2 show antiferromagnetic and weak ferromagnetic exchanges transmitted through μ2-Owater/μ1,3-carboxylate bridges and carboxylate single μ2-O bridges between Co2+ ions...

Two unprecedented three-dimensional (3D) true coordination polymorphs, namely, [Pb2(phda)2(H2O)]n·2nH2O (1a, and 1b) (H2phda = 1,4-phenylenediacetate acid), which show distinct novel topological networks, have been successfully prepared by utilizing a kinked flexible H2phda. This work shows the first example of two different isomers reported for a flexible ligand acting as a bridge.

Two new interpenetrated metal-carboxylate frameworks (MCFs) [(CH3)2NH2][Zn2(BDC)(BTB)][Zn3(BTB)2(H2O)2]·4DMA·2C2H5OH·7H2O (MCF-25, 1, H2BDC = 1,4-benzenedicarboxylic acid, H3BTB = benzene-1,3,5-tribenzoic acid), and [(CH3)2NH2][Zn2(BDC)(BTB)]·3DMF·2H2O (MCF-26, 2), synthesized by solvothermal reaction and room-temperature evaporation, respectively, are constructed by Zn2(O2CR)5 (in 1 and 2) and Zn3(O2CR)6 (in 1) units incorporating mixed BDC2− and BTB3− ligands. 1 is composed of two different frameworks with 2D 63 bilayers and a rare (3,5)-connected 3D hms net giving an interesting 2D + 3D framework, whereas 2 features a novel 3-fold interpenetrated (3,5)-connected gra net with chiral, hexagonal helical channels. Structural analysis shows that the two 3D nets of hms in 1 and gra in 2 are strict isomers with the same components but different steric arrangements, which are derived from different orientations of the two axial carboxylate bridges in two isomeric Zn2(O2CR)5 SBUs.