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Four new metal–organic frameworks (MOFs), {[Zn3(L)(OH)(H2O)5]·NMP·2H2O}n (1), {[H2N(Me)2][Zn2(L)(H2O)]·DMF·H2O}n (2), {[Co5(L)2(H2O)11]·2H2O}n (3) and {[Mn5(L)2(H2O)12]·6H2O}n (4), were assembled employing a symmetrical V-shaped rigid multicarboxylic acid ligand H5L (H5L = 2,4-di(3′,5′-dicarboxylphenyl)benzoic acid) with different metal ions, resulting in versatile frameworks as well as various types of coordination modes of H5L. 1 forms a three-dimensional (3D) 4-connected sra net based on trinuclear [Zn3(μ3-OH)(μ2-COO)(μ1-COO)4] clusters, while 2 displays a 3D (4,6)-connected net based on two types of binuclear [Zn2(μ2-COO)2(μ1-COO)4] and [Zn2(μ2-COO)4] clusters. 3 and 4 contain similar [M3(μ2-COO)4(μ1-COO)2] (3, M = Co; 4, M = Mn) clusters but result in different 4-connected 3D and 2D frameworks, respectively. 1 and 2 show solid-state luminescence properties at ambient temperature. Meanwhile, 1 shows high selectivity and sensitivity for not only Fe3+ cations but also for CrO42−, Cr2O72− and MnO4− anions via a luminescence quenching effect with a low detection limit, which thus means that it could be a potential crystalline material for detecting these anions. The mechanisms of the quenching effect and sensing properties of 1 are discussed in detail. In addition, 3 and 4 have the presence of antiferromagnetic interactions between the metal ions. [ABSTRACT FROM AUTHOR]

Six new complexes based on 5-(triazol-1-yl)nicotinic acid (HL), namely [Cu2(L)3(H2O)(OH)]n (1), [Co(L)2(H2O)2]n (2), [Mn(L)2(H2O)2]n (3), {[Co(L)(H2O)0.5(DMF)0.5(NO3)0.5]·(Cl)0.5·DMF·2H2O}n (4), {[Cu(L)(O)0.5]·CH3OH·2.5H2O}n (5) and {[Co2(L)4(H2O)]·2DMA·2H2O}n (6), were synthesized under hydro(solvo)thermal conditions. The L− ligand in 1–6 reveals various coordination modes and forms diverse secondary building units (SBUs) in the final structures. Complex 1 shows a 2D layered structure with a rare (3,8)-connected topology based on tetranuclear [Cu4(COO)6(H2O)2(OH)2N6] SBUs. 2 and 3 are isostructural and display 2D 4-connected sql nets with a point symbol of (44·62). 4 and 5 have similar spatial 3D porous frameworks, which can be simplified as a (3,6)-connected 2-nodal net via dinuclear [Co2(COO)2(O)2(NO3)(N)4] SBUs and [Cu2(COO)2(O)(N)4] SBUs, respectively. 6 is a 3D porous framework constructed by dinuclear [Co2(COO)4(H2O)(N)4] motifs with a uninodal 4-connected qtz net. The magnetic properties and gas sorption behaviour of these complexes were investigated carefully, showing that 3 exhibits ferrimagnetic character and 4 demonstrates its effective storage capacity for CO2 as well as high selectivity for CO2 over CH4 under ambient conditions. [ABSTRACT FROM AUTHOR]

Two new 2D MOFs, namely, {[Cd 2 (HL)(H 2 O)(DMF) 2 ]·(H 2 O)·(DMF)} n (1), {[Co 2 (HL)(H 2 O)(DMF) 2 ]·(H 2 O)·(DMF)} n (2) were constructed under the solvothermal conditions by using 2,4-di(2′,5′-dicarboxylphenyl)benzoic acid and d10 metal ion Cd(Ⅱ) and Co(Ⅱ). Because the diversity of ligands leads to two different coordination patterns in complexes 1–2 , resulting in 1 and 2 with multiple structures. Both 1 and 2 exhibit a 3D supramolecular framework, which based on different metal-oxygen chains. The chains form a 2D layered structure through the carboxyl oxygen atoms in the ligand. The solid-state luminescence spectra of 1 at room temperature showed that the maximum emission peak is 458 nm (λex = 346 nm). At the same time, 1 showed high fluorescence selectivity and low detection limit for Fe3+ cations, Cr 2 O 7 2− and CrO 4 2− anions in aqueous solution, and can be used as a potential multifunctional material for the detection of these substances. In addition, the fluorescence sensing properties and quenching mechanism of the above ions are discussed in detail. [Display omitted] • Two novel 2D MOFs were constructed based on a V-shaped rigid pentacarboxylic acid ligand. • Complexes 1 and 2 feature 2D frameworks based on diverse metal-oxygen chains with high open metal sites. • 1 shows high selectivity and sensitivity to detect Fe3+, Cr 2 O 7 2− and CrO 4 2− ions with low detection limit. • The fluorescence quenching mechanism of complex 1 was described in detail. [ABSTRACT FROM AUTHOR]