Unprecedented marriage of a cationic pentanuclear cluster and a 2D polymeric anionic layer based on a flexible tripodal ligand and a Cu(II) ion.

The anionic CdI(2)-type topological net, [Cu(2)(tci)(2)](2-), and the pentanuclear copper cluster cation [Cu(5)(tci)(2)(OH)(2)(H(2)O)(8)](2+) [tci = tris(2-carboxyethyl)isocyanurate] form a complementary 3D supramolecular framework. Interestingly, there exist centrosymmetric cyclic (H(2)O)(18) clusters in the cavities.

Tuning the framework topologies of Co(II)-doped Zn(II)-tetrazole-benzoate coordination polymers by ligand modifications: structures and spectral studies.

In our continuing efforts to explore the effects of ligand modifications on the structures and properties of their metal complexes, we studied the in situ [2 + 3] cycloaddition reactions of benzonitrile, o-phthalodinitrile, 3-cyanobenzoic acid, 4-cyanobenzoic acid with NaN(3) in the presence of Zn(II) and/or Co(II) salts under hydrothermal conditions, and obtained four new Co(II)-doped Zn(II)-tetrazole-benzoate coordination polymers with the formula of [Co(x)Zn(1-x)(L(m))(y)](n) [5-phenyl-1H-tetrazole (HL(1)) for 1, 2-(1H-tetrazol-5-yl)benzoic acid (H(2)L(2)) for 2, 3-(1H-tetrazol-5-yl)benzoic acid (H(2)L(3)) for 3, and 4-(1H-tetrazol-5-yl)benzoic acid (H(2)L(4)) for 4]. The structure of 1 shows a classical diamondoid net, while 2 and 3, take 2D layer structure with (4.6(2))(4.6.4.6) topology and 3D SrAl(2) topology, respectively. The structure of 4 exhibits a four-connected 3D network with rare non-diamondoid 6(6) topology. The coordination modes of the center metal and the ligands in the four complexes are almost the same, being tetrahedral or four-connected, but their topologies are quite different. Thus, the four structurally related ligands allow analysis of the effects of the disposition of a second functional carboxylate group on an aromatic ring and the twist angles of the carboxylate and tetrazoyl out of the plane of the aromatic ring on the overall structural topology of their complexes. Interestingly, the Co(II) ions were doped into the Zn(II) complexes, as confirmed by their macroscopical colors, inductively coupled plasma (ICP) analysis and UV-visible spectra. In addition, the photoluminescence of the four complexes in the solid state at room temperature was briefly studied.

Selective sampling and measurement of Cr (VI) in water with polyquaternary ammonium salt as a binding agent in diffusive gradients in thin-films technique.

A diffusive gradients in thin films (DGT) device with polyquaternary ammonium salt (PQAS) as a novel binding agent (PQAS DGT) combined with graphite furnace atomic absorption spectrometry (GFAAS) was developed for the selective sampling and measurement of Cr (VI) in water. The performance of PQAS DGT was independent of pH 3-12 and ionic strength from 1 × 10(-3) to 1 molL(-1). DGT validation experiments showed that Cr (VI) was measured accurately as well as selectively by PQAS DGT, whereas Cr (III) was not determined quantitatively. Compared with diphenylcarbazide spectrophotometric method (DPC), the measurement of Cr (VI) with PQAS DGT was agreement with that of DPC method in the industrial wastewater. PQAS-DGT device had been successfully deployed in local freshwater. The concentrations of Cr (VI) determined by PQAS DGT coupled with GFAAS in Nuer River, Ling River and North Lake were 0.73 ± 0.09 µg L(-1), 0.50 ± 0.07 µg L(-1) and 0.61 ± 0.07 µg L(-1), respectively. The results indicate that PQAS DGT device can be used for the selective sampling and measurement Cr (VI) in water and its detection limit is lower than that of DPC method.

Polymeric silver(I) complexes with pyridyl dithioether ligands: experimental and theoretical investigations on the coordination properties of the ligands.

The reactions of four flexible tetradentate ligands, 1,3-bis(2-pyridylthio)propane (L1), 1,4-bis(2-pyridylthio)butane (L2), 1,5-bis(2-pyridylthio)pentane (L3) and 1,6-bis(2-pyridylthio)hexane (L4) with AgX (X = BF4-, ClO4-, PF6-, or CF3SO3-) lead to the formation of seven new complexes: [AgL1(BF4)]2 (1), [[AgL2](ClO4)]infinity (2), [[AgL2(CH3CN)](PF6)]infinity (3), [[AgL3](BF4)(CHCl3)]2 (4), [[AgL3(CF3SO3)](CH3OH)(0.5)]infinity (5), [[Ag2L4(2)](BF4)2]infinity (6), and [[AgL4](PF6)]infinity (7), which have been characterized by elemental analyses, IR spectroscopy, and X-ray crystallography. Single-crystal X-ray analyses show that complexes 1 and 4 possess dinuclear macrometallacyclic structures, and complexes 2, 3 and 5-7 take chain structures. In all the complexes, the nitrogen atoms of ligands preferentially coordinate to silver atoms to form normal coordination bonds, while the sulfur atoms only show weak interactions with silver atoms and the intermolecular AgS weak contacts connect the low-dimensional complexes into high-dimensional supramolecular networks. Additional weak interactions, such as pi-pi stacking, F...F weak interactions, Ag...O contacts or C-H...O hydrogen bonds, also help to stabilize the crystal structures. It was found that the parity of the -(CH2)n- spacers (n = 3-6) affect the orientation of the two terminal pyridyl rings, thereby significantly influence the framework formations of these complexes. The coordination features of ligands and their conformation changes between free and coordination states have been investigated by DFT calculations.