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Two new supramolecular compounds, [(H4aobtc)0.5(H2O)0.5] (1) and [(H3aobtc)(H2bipy)0.5] (2) (H4aobtc = azoxybenzene-3,3′,4,4′-tetracarboxylic acid), were synthesized and characterized. Compound 1 has a complicated three-dimensional hydrogen bonding network with 4-connected {33.62.7} topology. Compound 2 also shows a three-dimensional supramolecular motif with hexagonal topology. The result indicated that hydrogen bonding interactions from different molecular synthons take important roles in the formation of supramolecular architectures. [ABSTRACT FROM PUBLISHER]

A polyoxoniobate, [Cu(en)2]4{[Nb6O19H2]K(H2O)5}2 ⋅ (H2en) ⋅ 17H2O (en = ethylenediamine) (1), has been synthesized and characterized by elemental analysis, IR, XPS, TGA, and single-crystal X-ray diffraction. Compound 1 crystallizes in the triclinic system, space group P1, with a = 12.3533(16) Å, b = 12.7188(16) Å, c = 29.626(4) Å, α = 93.235(2)°, β = 96.094(1)°, γ = 106.098(2)°, V = 4429.0(10) Å3, Z = 2. The polyoxoanion is composed of a Lindqvist-type [Nb6O19H2]6- dimer bi-bridged via two K+. K+ is 10-coordinate with 10 oxygens, three from one [Nb6O19H2]6-, one from a terminal oxygen of another [Nb6O19H2]6- moiety, and the other six from water molecule. Adjacent dimeric polyoxoanions are linked to form an infinite 1-D chain via O-H ··· O hydrogen-bonding interactions which exist between the two water trimers and the dimeric polyoxoanions. [ABSTRACT FROM AUTHOR]

A series of thiosemicarbazone derivatives of benzo-15-crown-5 were synthesized efficiently at room temperature using hydrogenchloride acid (HCl) as catalyst. Their anion recognition properties of a, b and c were studied, the result show they exhibit highly selective binding and sensing of F-, MeCO2- and n-C3H7CO2- in CH3CN (F- > n-C3H7CO2- > MeCO2- > > Cl-, Br- and I-). Especially receptor c shows different UV-Vis spectrum of F- from MeCO2-and C3H7CO2-, in addition to the color of the solution change from colorless to yellow upon the addition of F-, these two points make it suitable to be used as colorimetric anion sensor to identify fluoride anion from other halide anions and carboxylate anions by naked-eye. The connection between receptor and anion is by hydrogen bonding interactions, the binding ratio is 1:1, which have been confirmed by UV-vis inspection spectra in CH3CN and 1HMR in DMSO-d6. [ABSTRACT FROM AUTHOR]