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A two-dimensional Cd(II) metal–organic framework (MOF) was constructed from a tris(pyridinium)-based hexacarboxylate zwitterionic ligand. The MOF shows a novel fashion of 2-fold 2D → 2D parallel entanglement. It is the entanglement that dictates close interlayer contacts between carboxylate (electron donor) and pyridinium (acceptor), which in turn impart the MOF with reversible photochromic properties through photoinduced electron transfer (PET). This is an extension of PET-based photochromism from bipyridinium to multipyridinium compounds. Thanks to the photoresponsive behaviour, the fluorescence of the MOF can be reversibly modulated or switched by photoirradiation. Besides, the fluorescence of the water-stable MOF in aqueous dispersion is very sensitive to nitrofuran antibiotics with high selectivity, and therefore the MOF is a good candidate of efficient and regenerable sensing material for determination of the antibiotics in water media. [ABSTRACT FROM AUTHOR]

The Zn(II) MOF with a tripyridinium-based hexacarboxylate shows direct color change on exposure to small primary amines and UV-assisted color response on exposure to small alcohols. The reversible, group-specific and size-selective chemochromic/chemophotochromic behaviours are ascribed to spontaneous/photoinduced guest-to-host electron transfer within the unique confined space furnished with electron-deficient sites. [ABSTRACT FROM AUTHOR]

A novel nickel(ii) complex, [Ni(2,2′-bpy)3](H2SBTC)(H2O)5 (1) (2,2′-bpy = 2,2′-bipyridyl), was synthesized based on [Ni(2,2′-bpy)3]2+ discrete units and a partially deprotonated sulfonate–carboxylate ligand of H4SBTC (5-sulfonyl-1,2,4-benzentricarboxylic acid). The adjacent [Ni(2,2′-bpy)3]2+ cationic units were connected to H2SBTC2− anions by hydrogen bonds to form a one-dimensional (1-D) chain. The 1-D chains were further linked using hydrogen bonds from free water molecules and H2SBTC2− anions to generate a two-dimensional (2-D) plane structure. The proton conductivity of 1 reaches 1.3 × 10−4 S cm−1 at 318 K, 98% RH. Furthermore, hybrid membranes composed of polyvinyl alcohol (PVA) and 1 as fillers were prepared with different mass percentages. The proton conductivity of 1@PVA-5 was found to be 1.6 × 10−3 S cm−1 at 313 K and 98% RH. The large number of alcoholic hydroxyl groups in PVA promote the resulting conductivity. [ABSTRACT FROM AUTHOR]

A microporous europium metal–organic framework (Eu-MOF), namely, {[Eu3(bpydb)3(HCOO)(OH)2(DMF)]·3DMF·2H2O}n (1) with asymmetric trinuclear metal clusters extended by 4,4′-(4,4′-bipyridine-2,6-diyl) dibenzoic acid has been synthesized via the solvothermal method. PXRD of 1 confirms that it possesses excellent water stability and pH stability. The photo-luminescence properties of 1 exhibit effective recognition of Cr2O72−, MnO4−, and Cr3+ ions and SDBS. Furthermore, a wide linear range, high quenching constant and a low detection limit reveal that 1 can potentially act as a luminescence-based sensor for quantitative and highly sensitive detection of Cr2O72−, MnO4−, and Cr3+ ions as well as SDBS in aqueous solutions. To the best of our knowledge, the detection limit of 1 is the lowest value reported for Ln-MOF-based luminescent sensors to detect Cr2O72− ions (0.5 μM) in aqueous solutions. The use of a rare earth fluorescent probe for detecting MnO4− ions is not common. It is the first time that Ln-MOF as a fluorescence probe is used for detecting SDBS. Moreover, fluorescent-based test papers of 1 have also been prepared, which can be helpful to develop visual detection for Cr2O72−, MnO4−, and Cr3+ ions as well as SDBS in daily applications. [ABSTRACT FROM AUTHOR]

A new metal–organic framework (MOF), [{(H3O)[Eu (SBDB)(H2O)2]}n] (H4SBDB = 1,5-disulfo-benzene-2,4-dicarboxylic acid) (1), was successfully synthesized under solvothermal conditions. Ten central Eu3+ ions are coordinated by the H4SBDB ligands and two coordination water molecules. The adjacent Eu3+ ions are connected by oxygen atoms from carboxyl groups, forming a 1D chain. 1D chains are linked by H4SBDB ligands to induce a 2D infinitely extensible planar structure, and then connected by hydrogen bonds to form a 3D supernetwork structure. Complex 1 exhibits excellent thermal and chemical stability. AC impedance analysis shows that the highest proton conductivity of 1 reaches up to 1.0 × 10−4 S cm−1 (338 K, 98% RH). Furthermore, complex 1 is an excellent luminescence-based sensor with high sensitivity and a low detection limit for ascorbic acid (AA) in aqueous solutions. [ABSTRACT FROM AUTHOR]

Recently, considerable attention has been paid to European eggs that were found to contain the poisonous insecticide fipronil. Excessive consumption of fipronil can harm the human body, in particular, the liver, thyroid, nervous system and kidneys. As a consequence, there is an urgent need to develop a method to detect fipronil. In this work, a lanthanide coordination polymer [Eu(SIP)(H2O)4]n (1) (NaH2SIP = 5-sulfoisophthalic acid monosodium salt) was synthesized and characterized by single-crystal X-ray crystallography, elemental analysis, infrared spectrum and powder X-ray diffractions. The X-ray studies show that 1 is a two-dimensional layered structure, which is constructed of fused {[Eu(H2O)4]3(SIP)3} pseudo-hexagonal grids. The luminescence properties of 1 exhibit effective recognition for fipronil in methanol solution. Furthermore, a wide linear range (10−6–10−4 M), a low detection limit of 0.8 μM, high selectivity and excellent recyclability, reveal that 1 can potentially act as a luminescence-based sensor for quantitative and highly sensitive detection of fipronil. To the best of our knowledge, it is the first time that a metal–organic coordination polymer, as a fluorescent-based probe, has been used for the detection of fipronil. Moreover, fluorescent-based test papers of 1 have also been prepared, which can be regarded as a simple and practical method for detecting fipronil. [ABSTRACT FROM AUTHOR]

Two novel lanthanide–organic frameworks, {[Ln3(bpydb)3(HCOO)(OH)2(DMF)]·3DMF·xH2O}n (Ln = Eu3+ (1) and x = 2; Tb3+ (2) and x = 1; bpydbH2 is 4,4′-(4,4′-bipyridine-2,6-diyl) dibenzoic acid; DMF denotes N,N′-dimethylformamide), have been synthesized and structurally characterized. Topological analysis reveals that 1 and 2 are 12-connected frameworks with an fcu topology, which are based on rod-shaped {Ln6} as 12-connected nodes. AC impedance analysis shows that the proton conductivity of 1 and 2 reaches up to 1.7 × 10−4 S cm−1 at 325 K and 1.1 × 10−4 S cm−1 at 334 K, respectively, under 98% RH. Furthermore, the polymer composite membranes of poly(vinyl alcohol) (PVA) and 1 or 2 as fillers with different mass percentages (X%, with the composite membrane denoted as 1@PVA-X or 2@PVA-X) were fabricated. The proton conductivities of both 1@PVA-10 and 2@PVA-10 are higher than those of 1 and 2 under the same conditions, which can be interpreted that the PVA polymer can provide a continuous proton transfer pathway for 1 and 2. To the best of our knowledge, it is the first composite based on Ln–MOFs and a polymer as proton exchange membranes. This research may contribute to the further development of Ln–MOFs in the field of proton exchange membranes in fuel cells. [ABSTRACT FROM AUTHOR]

Monodisperse silver nanocages (AgNCs) with specific interiors were successfully synthesized by an azeotropic distillation (AD) assisted method and exhibited excellent catalytic activities for reduction of 4-nitrophenol (4-NP) into 4-aminophenol (4-AP) due to the unique hollow morphology and small thickness of the silver shell. [ABSTRACT FROM AUTHOR]

Phenylene ethynylene-based p-conjugated polymers grafted with dithiafulvenyl groups on their side chains were found to be efficient in dispersing single-walled carbon nanotubes in a selective and controllable way. [ABSTRACT FROM AUTHOR]

A bisbenzimidazole was discovered to bind helix DNA, while related benzobisimidazole derivatives were found to bind and induce different G-quadruplex isomers.