Determination of Urea in Swimming Pool Water Using High-Performance Liquid Chromatography with Online Postcolumn Derivatization by Xanthydrol.

A reversed-phase isocratic elution high-performance liquid chromatography method coupled with fluorescence detection has been developed to determine urea concentration via online postcolumn derivatization. Swimming pool water samples were filtered through 0.20 µm syringe filters. When the temperature of reaction coil was 40°C, urea was derivatized well with xanthydrol methanol solution (0.1 g/L) containing 0.50% hydrochloric acid with a flow rate of 0.20 mL/min. Successful separation was achieved by using Shim-pack VP-ODS C18 (250 mm × 4.6 mm, 5 µm) column, with a mobile phase containing phosphoric acid solution (0.01 mol/L) at a flow rate of 0.80 mL/min. Retention time and external standard method were used for qualitative and quantitative urea analysis, respectively. Under the established conditions, the limit of detection, linear range, correlation coefficient, recovery and relative standard deviation was 0.09 mg/L, 1.0-100.0 mg/L, 0.9998, 87.0-105.3% and 0.95-4.8%, respectively. Ammonia, thiourea and trichloroisocyanuric acid did not interfere with urea analysis. The method showed satisfactory results with high precision, accuracy, recovery, as well as sensitivity, for the determination of urea in swimming pool water.

Stereoselective Access to Spirooxindoles and Bisoxindoles Through Organocatalyzed Asymmetric Divergent Transformations of Isatin-derived MBH Carbonates.

An interesting ß-isoquinidine catalyzed divergent reaction was developed to produce either spirocyclopentene oxindoles, spirocyclopentadiene oxindoles or bisoxindoles in a high enantioselective fashion. The utility of this protocol was demonstrated by the versatile transformations of the products. This work not only represents the first highly stereoselective intermolecular catalytic asymmetric allylic alkylation reaction between two isatin-derived MBH carbonate molecules but also constitutes a rare example of isatin-derived MBH carbonate-based enantioselective and α-regioselective [3+2] cycloaddition reactions.

Cu@Pd/C with Controllable Pd Dispersion as a Highly Efficient Catalyst for Hydrogen Evolution from Ammonia Borane.

A series of Cu@Pd/C with different Pd contents was prepared using the galvanic reduction method to disperse Pd on the surface of Cu nanoparticles on Cu/C. The dispersion of Pd was regulated by the Cu(I) on the surface, which was introduced by pulse oxidation. The Cu2O did not react during the galvanic reduction process and restricted the Pd atoms to a specific area. The pulse oxidation method was demonstrated to be an effective process to control the oxidization degree of Cu on Cu/C and then to govern the dispersion of Pd. The catalysts were characterized by transmission electron microscopy (TEM), high-resolution transmission electron microscope (HRTEM), high angular annular dark field scanning TEM (HAADF-STEM), energy-dispersive spectroscopy (EDS) mapping, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), auger electron spectroscopy (AES), and inductively coupled plasma optical emission spectrometer (ICP-OES), which were used to catalyze the hydrogen evolution from ammonia borane. The Cu@Pd/C had much higher activity than the PdCu/C, which was prepared by the impregnation method. The TOF increased as the Cu2O in Cu/C used for the preparation of Cu@Pd/C increased, and the maximum TOF was 465 molH2 min-1 molPd-1 at 298 K on Cu@Pd0.5/C-640 (0.5 wt % of Pd, 640 mL of air was pulsed during the preparation of Cu/C-640). The activity could be maintained in five continuous processes, showing the strong stability of the catalysts.

Facile Preparation of Pd/UiO-66-v for the Conversion of Furfuryl Alcohol to Tetrahydrofurfuryl Alcohol under Mild Conditions in Water.

The hydrogenation of furan ring in the biomass-derived furans is of great importance for the conversion of biomass to valuable chemicals. Fabrication of high activity and selectivity catalyst for this hydrogenation under mild conditions was one of the focuses of this research. In this manuscript, UiO-66-v, in which vinyl bonded to the benzene ring, was first prepared. Then, the uniformly distributed vinyl was used as the reductant for the preparation of Pd/UiO-66-v. The catalyst was characterized by X-ray diffraction, thermogravimetric, N2 physical adsorption/desorption, X-ray photoelectron spectroscopy, scanning electron microscope, transmission electron microscopy, energy dispersive spectrometer elemental mappings, and inductively coupled plasma atomic emission spectroscopy to find the Pd/UiO-66-v had a narrow palladium nanoparticles size of 3-5 nm and maintained the structure and thermal stability of UiO-66-v. The Pd/UiO-66-v was used for the hydrogenation of furfuryl alcohol to tetrahydrofurfuryl alcohol in water. 99% conversion of furfuryl alcohol was obtained with 90% selectivity to tetrahydrofurfuryl alcohol after reacted at 0.5 MPa H2, 303 K for 12 h. The Pd/UiO-66-v was proved to be effective for the hydrogenation of furan ring in furans and could be used for at least five times.

Carbon-carbon bond forming reactions of acetylenic esters and ketones within frustrated phosphane/borane Lewis pair frameworks.

The three-component reactions of bulky diarylbutenylphosphanes with dimethyl acetylenedicarboxylate (1a) and the strong boron Lewis acid B(C6F5)3 give the ylide-substituted cyclopropane derivatives 26. The acetylenic ester 1a and ketone 1b react with oligomethylene bridged frustrated phosphane/borane Lewis pairs to give the bicyclic C-H insertion/C-C coupling reaction products. The formal carbene products are formed by means of stepwise sequences involving polar intermediate.

A metal-organic gel based on Fe(iii) and bi-pyridine ligand for template synthesis of core/shell composite polymer nanowires.

In this study, a novel self-assembled metal-organic gel was synthesized from ferric nitrate and a di-topic ligand, bis(3-pyridyl)terephthalate. The gel consisted of a three dimensional network of uniform nanofibers. The gelation exhibited high selectivity to Fe(iii) based on metal-ligand coordination. The molar ratio of Fe3+ to ligand had a large influence on the assembly process and the morphology of the gel. The metallogel displayed multi-stimuli responsiveness and excellent heat resistance, thus was further applied as a thermo-stable template for the polymerization of N,N'-methylene bisacrylamide to produce the core/shell polymer composite nanowires. Subsequently, the polymer nanotubes were obtained after ammonia post-treatment, comfirming the feasibility of the template synthesis strategy. According to the rheological measurements, the gel-like products of the composite nanowires exhibited better mechanical strength compared to the gel template.

A new copper-based metal-organic framework as a promising heterogeneous catalyst for chemo- and regio-selective enamination of ß-ketoesters.

Assembly of 5-nitro-1,2,3-benzenetricarboxylic acid (H3nbta) with Cu(II) in the presence of 1,3-bis(1,2,4-triazol-1-yl)propane (1,3-btp) leads to a new metal-organic framework, [Cu(Hnbta)(1,3-btp)]·2H2O (A1), which is shown to be an efficient and recyclable heterogeneous catalyst for enamination of ß-ketoesters with excellent product yields and selectivity.

(±)-Pestalachloride D, an antibacterial racemate of chlorinated benzophenone derivative from a soft coral-derived fungus Pestalotiopsis sp.

A new antibacterial chlorinated benzophenone derivative, (±)-pestalachloride D (1), along with a related analog, (±)-pestalachloride C (2), was recently isolated from the marine-derived fungus Pestalotiopsis sp. isolated from a soft coral Sarcophyton sp. collected from Yongxing Island in the South China Sea. Both chiral HPLC analysis and single-crystal X-ray data indicated that 1 is a racemic mixture. Interestingly, 1 did not exhibit any effect in the zebrafish embryo teratogenicity assay, while 2 led to abnormal growth. The potential impact on zebrafish embryo growth is discussed based on their crystal structures. The main difference of crystal structures between 1 and 2 is that the six-member non-aromatic ring (O4, C10, C9, C8, C2', and C3') in 1 exhibits a distorted chair conformation, while 2 shows a distorted boat conformation. Moreover, compounds 1 and 2 both exhibited moderate antibacterial activity.

Syntheses, structures, luminescence, and magnetic properties of one-dimensional lanthanide coordination polymers with a rigid 2,2'-bipyridine-3,3',6,6'-tetracarboxylic acid ligand.

A series of novel one-dimensional (1-D) lanthanide coordination polymers (CPs), with the general formula {[Ln(bptcH)(H(2)O)(2)]·H(2)O}(n) (Ln = Nd(III) (1), Eu(III) (2), Gd(III) (3), Tb(III) (4), Dy(III) (5), Ho(III) (6), or Er(III) (7)) have been synthesized by the solvothermal reactions of the corresponding lanthanide(III) picrates and 2,2'-bipyridine-3,3',6,6'-tetracarboxylic acid (bptcH(4)). These polymers have been structurally characterized by single-crystal X-ray diffraction, IR, PXRD, thermogravimetric (TGA), and elemental analysis. Coordination polymers 1-7 are isostructural; they possess the same 3D supramolecular architectures and crystallize in triclinic space group P1̅. The frameworks constructed from dinuclear lanthanide building blocks exhibit one-dimensional double-stranded looplike chain architectures, in which the bptcH(3-) ions adopted hexadentate coordination modes. The Eu(III) (2) and Tb(III) (4) polymers exhibit characteristic photoluminescence in the visible region. The magnetic properties of polymers 2, 3, and 5 have been investigated through the measurement of their magnetic susceptibilities over the temperature range of 1.8-300 K.

Bioactive hydroanthraquinones and anthraquinone dimers from a soft coral-derived Alternaria sp. fungus.

Five new hydroanthraquinone derivatives, tetrahydroaltersolanols C-F (1-4) and dihydroaltersolanol A (5), and five new alterporriol-type anthranoid dimers, alterporriols N-R (12-16), along with seven known analogues (6-11 and 17), were isolated from the culture broth and the mycelia of Alternaria sp. ZJ-2008003, a fungus obtained from a Sarcophyton sp. soft coral collected from the South China Sea. Their structures and the relative configurations were elucidated using comprehensive spectroscopic methods including 1D and 2D NOE spectra as well as single-crystal X-ray crystallography. Compound 13 represents the first isolated alterporriol dimer with a C-4-C-4' linkage, and the absolute configuration of 4 was determined using the modified Mosher's method. Compounds 1 and 15 exhibited antiviral activity against the porcine reproductive and respiratory syndrome virus (PRRSV), with IC50 values of 65 and 39 µM, respectively. Compound 14 showed cytotoxic activity against PC-3 and HCT-116 cell lines, with IC50 values of 6.4 and 8.6 µM, respectively.

Penicinoline, a new pyrrolyl 4-quinolinone alkaloid with an unprecedented ring system from an endophytic fungus Penicillium sp.

A new pyrrolyl 4-quinolinone alkaloid with an unprecedented ring system, named penicinoline (1) was isolated from a mangrove endophytic fungus. The structure of 1 was elucidated by spectroscopic methods and comparison with its derivative, penicinotam (1a), an unexpected lactam that was obtained from 1 by intramolecular dehydration. The structure of 1a was unambiguously confirmed by single-crystal X-ray analysis. Penicinoline (1) showed potent in vitro cytotoxicity toward 95-D and HepG2 cell lines with IC(50) values of 0.57 and 6.5 microg/mL, respectively.

2,2'-Dimeth-oxy-6,6'-dinitro-biphen-yl.

In the title compound, C(14)H(12)N(2)O(6), the half mol-ecule in the asymmetric unit of the cell is completed by a crystallographic twofold rotation axis, and the two benzene rings of the complete mol-ecule make a dihedral angle of 60.5 (3)°. Furthermore, inter-molecular weak C-H⋯O hydrogen bonds link adjacent mol-ecules, forming a two-dimensional sheet. These sheets are stablized by face-to-face weak π-π contacts [centroid-centroid distance = 3.682 (1) Å] between the nearly parallel [dihedral angle = 0.12 (7)°] benzene rings of the neighboring mol-ecules, resulting in a three-dimensional network.

2-Iodo-3-meth-oxy-6-methyl-pyridine.

The title compound, C(7)H(8)INO, which crystallizes with three independent mol-ecules in the asymmetric unit, was prepared by the reaction of 3-meth-oxy-6-methyl-pyridine with KI and I(2) in tetra-hydro-furan solution. In the crystal structure, the three independent mol-ecules are arranged in a similar orientation with the three polar meth-oxy groups aligned on one side and the three non-polar methyl groups on the other side. The three mol-ecules, excluding methyl H atoms, are essentially planar, with r.m.s. deviations of 0.0141 (1), 0.0081 (1) and 0.0066 (2)Å. The three pyridine rings make dihedral angles of 58.09 (3) 66.64 (4) and 71.5 (3)°. The crystal structure features rather weak inter-molecular C-H⋯O hydrogen bonds, which link two mol-ecules into dimers, and short I⋯N contacts [4.046 (3) Å].

4,4',6,6'-Tetra-methyl-2,2'-bipyrimidine hexa-hydrate.

In the title compound, C(12)H(14)N(4)·6H(2)O, the two pyrimidine rings make a dihedral angle of 5.285 (6)°. Inter-molecular O-H⋯O hydrogen bonds link the six water mol-ecules, generating edge-fused four-, five- or six-membered ring motifs and forming two-dimensional sheets. The sheets are stabilized by the formation of O-H⋯N hydrogen bonds between the water mol-ecules and the bipyrimidine mol-ecules, resulting in a three-dimensional network.

Dimethyl 6,6'-dicyano-2,2'-bipyridine-3,3'-dicarboxyl-ate.

In the title compound, C(16)H(10)N(4)O(4), the two pyridine rings are twisted by 44.41 (2)° and the ester groups form dihedral angles of 48.77 (4) and 45.75 (2)° with the corresponding pyridine rings. The crystal structure is stabilized by inter-molecular C-H⋯O hydrogen bonds and π-π stacking inter-actions between the pyridine rings [centroid-to-centroid distance 3.797 (2) Å].

Tetra-aqua-diimidazole-nickel(II) naphthalene-1,5-disulfonate.

The triclinic unit cell of the title compound, [Ni(C(3)H(4)N(2))(2)(H(2)O)(4)](C(10)H(6)O(6)S(2)), contains one centrosymmetric cation and one centrosymmetric anion. In the cation, the Ni(II) ion is six-coordinated by two imidazole ligands [Ni-N = 2.0568 (14) Å] and four water mol-ecules [both independent Ni-O distances are 2.098 (1) Å] in a distorted octa-hedral geometry. Inter-molecular O-H⋯O and N-H⋯O hydrogen bonds form an extensive three-dimensional network, which consolidates the crystal packing.

Bis(3-meth-oxy-6-methyl-2-pyrid-yl) ether.

In the mol-ecule of the title compound, C(14)H(16)N(2)O(3), the dihedral angle between the pyridyl rings is 87.74 (3)°. In the crystal structure, inter-molecular C-H⋯O hydrogen bonds link the mol-ecules into infinite zigzag chains.

Bis[bis(1H-imidazole-κN)silver(I)] naphthalene-1,5-disulfonate.

The title compound, [Ag(C(3)H(4)N(2))(2)](2)(C(10)H(6)O(6)S(2)), exists in the form of isolated cations and anions with electrostatic inter-action between them. The Ag atom is two-coordinated by the N atoms of two crystallographically independent imidazole mol-ecules. The naphthalene-1,5-disulfonate anion is located on a crystallographic center of symmetry. The cations and anions are connected through inter-molecular N-H⋯O hydrogen bonds.

6,6'-Dimeth-oxy-2,2',3,3',5-penta-nitro-1,1'-biphen-yl.

In the axially chiral title compound, C(14)H(9)N(5)O(12), the dihedral angle between the two benzene rings is 86.0 (8)°. In the crystal structure, the mol-ecules display a two-dimensional framework formed by weak inter-molecular C-H⋯O hydrogen bonds.

1,1-Bis(4-fluoro-phen-yl)-3,4-dihydro-1H-1,3-oxazino[3,4-a]indole.

The title compound, C(23)H(17)F(2)NO, which crystallizes with two independent mol-ecules in the asymmetric unit, was prepared by the cyclization of 4-[2-bis-(4-fluoro-phen-yl)methyl-eneamino]but-3-yn-1-ol at room temperature. The mol-ecules display a tripod conformation. The two fluoro-phenyl rings make dihedral angles of 79.26 (2) and 85.87 (1)° [86.53 (1) and 83.67 (2)° in the second mol-ecule] with the indole ring, and the dihedral angles between the fluoro-phenyl rings are 67.74 (2) and 66.33 (2)°, respectively. Furthermore, the indole rings are located on the edge of the respective oxazine half-chair ring systems. Nonconventional C-H⋯π contacts between indole and fluoro-phenyl rings are observed.