New solid phase methodology for the synthesis of biscoumarin derivatives: experimental and in silico approaches.

The simple and greener one-pot approach for the synthesis of biscoumarin derivatives using catalytic amounts of nano-MoO3 catalyst under mortar-pestle grinding was described. The use of non-toxic and mild catalyst, cost-effectiveness, ordinary grinding, and good to the excellent yield of the final product makes this procedure a more attractive pathway for the synthesis of biologically remarkable pharmacophores. Accordingly, biscoumarin derivatives were successfully extended in the developed protocols. Next, a computational investigation was performed to identify the potential biological targets of this set of compounds. In this case, first, a similarity search on different virtual libraries was performed to find an ideal biological target for these derivatives. Results showed that the synthesized derivatives can be α-glucosidase inhibitors. In another step, molecular docking studies were carried out against human lysosomal acid-alpha-glucosidase (PDB ID: 5NN8) to determine the detailed binding modes and critical interactions with the proposed target. In silico assessments showed the gold score value in the range of 17.56 to 29.49. Additionally, molecular dynamic simulations and the MM-GBSA method of the most active derivative against α-glucosidase were conducted to study the behavior of selected compounds in the biological system. Ligand 1 stabilized after around 30 ns and participated in various interactions with Trp481, Asp518, Asp616, His674, Phe649, and Leu677 residues.

Feasibility of applying the LED-UV-induced TiO2/ZnO-supported H3PMo12O40 nanoparticles in photocatalytic degradation of aniline.

In the present study, TiO2/ZnO-supported phosphomolybdic acid nanoparticles are investigated by the impregnation method, followed by analyzing their photocatalytic activity under UV-LED light and degradation kinetics degrading aniline as an organic pollutant model. Nanoparticle characteristics and the remaining Keggin structure in the nanocomposites were confirmed by means of FESEM, FTIR, and XRD analyses. Heterogenization of phosphomolybdic acid on TiO2 and ZnO nanoparticles resulted in the improved light absorption intensity and decreased band gap of nanocomposites. Photocatalytic degradation of aniline was also improved for composite nanoparticles and reached to 25.62, 43.48, and 38.25% for TiO2/HPMo, ZnO/HPMo, and TiO2/ZnO/HPMo, respectively. Overall, the results showed a good fit to the Langmuir-Hinshelwood kinetic model.

Fabrication of a novel electrochemical sensor for determination of hydrogen peroxide in different fruit juice samples.

A new hydrogen peroxide (H2O2) sensor is fabricated based on a multiwalled carbon nanotube-modified glassy carbon electrode (MWCNT-GCE) and reactive blue 19 (RB). The charge transfer coefficient, α, and the charge transfer rate constant, ks, of RB adsorbed on MWCNT-GCE were calculated and found to be 0.44 ± 0.01 Hz and 1.9 ± 0.05 Hz, respectively. The catalysis of the electroreduction of H2O2 by RB-MWCNT-GCE is described. The RB-MWCNT-GCE shows a dramatic increase in the peak current and a decrease in the overvoltage of H2O2 electroreduction in comparison with that seen at an RB modified GCE, MWCNT modified GCE, and activated GCE. The kinetic parameters such as α and the heterogeneous rate constant, k', for the reduction of H2O2 at RB-MWCNT-GCE surface were determined using cyclic voltammetry. The detection limit of 0.27µM and three linear calibration ranges were obtained for H2O2 determination at the RB-MWCNT-GCE surface using an amperometry method. In addition, using the newly developed sensor, H2O2 was determined in real samples with satisfactory results.

Humic acid degradation by the synthesized flower-like Ag/ZnO nanostructure as an efficient photocatalyst.

Nano-sized flower-like Ag/ZnO was synthesized by a simple method using zinc acetate and silver acetate under hydrothermal condition. Powder X-ray diffraction (PXRD) and transmission electron microscopy (TEM) were used to characterize the structure and morphology of the synthesized powder. Nano flower-like Ag/ZnO was used as a photocatalyst for degradation of humic acid in aqueous solution. The disappearance of HA was analyzed by measuring the absorbance of sample at special wavelength (254 nm). The effects of various parameters such as amount of photocatalyst, pH, initial humic acid concentration and irradiation time on degradation rate were systematically investigated. Photodegradation efficiency was small when the photolysis was carried out in the absence of Ag/ZnO and it was also negligible in the absence of light. Approximately 70% of humic acid (50 mg/L) has been eliminated after 40 minutes in the presences of catalyst (catalyst dose o.6 g/L and pH =7) and UVA irradiation. While, 100% of humic acid has been eliminated with solar irradiation.

Two new neutral copper(II) complexes with dipicolinic acid and 3-amino-1H-1,2,4-triazole formed under different reaction conditions: synthesis, characterization, molecular structures and DNA-binding studies.

Two Cu(II) complexes, [Cu2(µ-atr)(pydc)2(H2O)4]·5H2O (1) and [Cu(atr)(pydc) (H2O)]·H2O (2), with pyridine-2,6-dicarboxylic acid (H2pydc) and 3-amino-1H-1,2,4-triazole (atr), have been synthesized and characterized. The interaction ability of the both complexes with native calf thymus DNA (CT-DNA) has been monitored as a function of the metal complex-DNA molar ratio. UV-vis spectrophotometry, circular dichroism (CD), thermal denaturation studies, cyclic voltammetry (CV) and viscosity measurements. The intrinsic binding constants K(b) of complexes 1 and 2, with CT-DNA obtained from UV-vis absorption studies were 4.7 (±0. 1) × 10(4) and 9.5 (±0. 1) × 10(4) M(-1), respectively. Further investigation of interaction mode was performed using viscosity, cyclic voltammetry and T(m) of CT-DNA studies as well as CD study, indicating complexes bind to DNA via an intercalation mode.

(E)-4-(2-Hy-droxy-3-meth-oxy-benzyl-idene-amino)-6-methyl-3-sulfanyl-idene-3,4-dihydro-1,2,4-triazin-5(2H)-one.

In the title mol-ecule, C(12)H(12)N(4)O(3)S, there is an intra-molecular O-H⋯N hydrogen bond. The dihedral angle between the benzene and triazine rings is 65.9 (3)°. In the crystal, N-H⋯S and O-H⋯N hydrogen bonds link the mol-ecules into chains along [010]. In addition, there are weak π-π stacking inter-actions between symmetry-related triazine rings with a centroid-centroid distance of 3.560 (3)°.

Simultaneous trace-levels determination of Hg(II) and Pb(II) ions in various samples using a modified carbon paste electrode based on multi-walled carbon nanotubes and a new synthesized Schiff base.

A modified carbon paste electrode based on multi-walled carbon nanotubes (MWCNTs) and 3-(4-methoxybenzylideneamino)-2-thioxothiazolodin-4-one as a new synthesized Schiff base was constructed for the simultaneous determination of trace amounts of Hg(II) and Pb(II) by square wave anodic stripping voltammetry. The modified electrode showed an excellent selectivity and stability for Hg(II) and Pb(II) determinations and for accelerated electron transfer between the electrode and the analytes. The electrochemical properties and applications of the modified electrode were studied. Operational parameters such as pH, deposition potential and deposition time were optimized for the purpose of determination of traces of metal ions at pH 3.0. Under optimal conditions the limits of detection, based on three times the background noise, were 9.0×10(-4) and 6.0×10(-4) µmol L(-1) for Hg(II) and Pb(II) with a 90 s preconcentration, respectively. In addition, the modified electrode displayed a good reproducibility and selectivity, making it suitable for the simultaneous determination of Hg(II) and Pb(II) in real samples such as sea water, waste water, tobacco, marine and human teeth samples.

Guanidinium hexa-aqua-zinc(II) bis[tris-(3-carb-oxy-pyridine-2-carboxyl-ato)zincate].

In the title mol-ecular salt, (CH(6)N(3))(1.30)[Zn(H(2)O)(6)](0.35)[Zn(C(7)H(4)NO(4))(3)](2), the Zn(II) atom (site symmetry 3) in the anion is coordinated by three N,O-bidentate 3-carb-oxy-pyridine-2-carboxyl-ate monoanions to generate a fac-ZnN(3)O(3) octa-hedral coordination geometry. The guanidinium cation (the C atom has site symmetry 3) and the octa-hedral hexa-aqua-zinc(II) dication (the Zn(2+) cation has site symmetry -3) are occupationally disordered in a 1.30:0.35 ratio. In the crystal, the components are linked by O-H⋯O and N-H⋯O hydrogen bonds to generate infinite (001) sheets. Weak aromatic π-π stacking [centroid-centroid distance = 3.797 (8) Å] is also observed in the crystal.

2-Amino-1-methyl-4-oxo-4,5-dihydro-1H-imidazol-3-ium chloride.

In the crystal structure of the title compound, C(4)H(8)N(3)O(+)·Cl(-), N-H⋯Cl hydrogen bonds link the components into chains along [010]. In addition, weak C-H⋯Cl hydrogen bonds link the chains into a two-dimensional network perpendicular to (001).

Bis(guanidinium) tris-(pyridine-2,6-dicarboxyl-ato-κ(3)O(2),N,O(6))zirconate(II) tetra-hydrate.

In the title complex, (CH(6)N(3))(2)[Zr(C(7)H(3)NO(4))(3)]·4H(2)O, the Zr(IV) ion lies on a twofold rotation axes and is coordinated by six O and three N atoms of three tridentate pyridine-2,6-dicarboxyl-ate ligands, forming a slightly distorted tricapped trigonal-prismatic geometry. In the crystal, O-H⋯O and N-H⋯O hydrogen bonds link the components into a three-dimensional network.

Supramolecular assembled of hexameric water clusters into a 1D chain containing (H2O)6 and [(H2O)4O2] stabilized by hydrogen bonding in a copper complex.

BACKGROUND: Various water clusters including hexamers, heptamers, octamers, decamers and 1D or 2D infinite water chains in a number of organic and inorganic-organic hybrid hosts, have been reported. RESULTS: {[Cu(pydc)(amp)].3H2O}n has been hydrothermally synthesized and characterized by elemental analysis and by IR spectroscopy. A wide range of hydrogen bonds (of the O-H...O, N-H...O and N-H...N type) are present in the crystal structure. Hydrogen bond interactions between the co-crystallized water molecules led to formation of six-membered rings with chair conformation. CONCLUSION: In {[Cu(pydc)(amp)].3H2O}n, there are three uncoordinated water molecules. Thermal methods confirm number of co-crystallized water molecules in polymer. Hydrogen bond interactions between the co-crystallized water molecules led to the formation of a six-membered ring with the chair conformation. These rings are part of a 1D chain containing six-membered O6 rings, which are alternately made from (H2O)6 and [(H2O)4O2] rings. [(H2O)4O2] rings are also in chair conformation.

Synthesis and Crystal Structure of a Five-Coordinate Complex of Copper(II) with 4-Nitrobenzenesulfonate and 2, 2'-Bipyridine.

[Cu(bipy)2Cl](nbs) (1) (bipy = 2,2'-bipyridine, nbs = 4-nitrobenzenesulfonate) was obtained from the reaction of 4-nitrobenzenesulfonyl chloride and 2-amine-4-methylopyridine with CuCl2 in the presence of 2,2'-bipyridine and characterized by elemental analysis, IR spectra and X-ray single-crystal diffraction. The asymmetric unit of (1) contains the cationic complex [Cu(bipy)2Cl]+ and, in the outer coordination sphere, an (nbs)- counter ion.

Preparation and Characterization of a New Example of a Double Salt of Nickel(II) Complexes.

A new double salt of nickel(II) complexes, formulated as, [Ni(bipy)(H2O)4][Ni(H2O)6][Ni(pydc)2]2 • 6H2O, (1), (pydc = pyridine-2,6-dicarboxylate anion, bipy = 2,2'-bipyridine) has been hydrothermally synthesized. Complex was characterized by FT-IR spectroscopy, elemental analysis and X-ray diffraction studies. The compound 1 consists of [Ni(H2O)6]2+, [Ni(bipy)(H2O)4]2+, two symmetry-independent anionic complexes [Ni(pydc)2]2- and six co-crystallized water molecules. In the crystal structure of compound 1, the formation of extensive O-H…O hydrogen bonds between uncoordinated water molecules and cationic or anionic complexes play important roles in stabilizing the corresponding lattice and formation of 3-dimensional networks.

Tris(1,10-phenanthroline-κN,N')nickel(II) dinitrate tetra-hydrate.

In the title complex, [Ni(C(12)H(8)N(2))(3)](NO(3))(2)·4H(2)O, the Ni(II) ion is octa-hedrally coordinated by three bidentate 1,10-phenanthroline ligands, each forming a five-membered chelate ring. In the crystal, O-H⋯O and C-H⋯O hydrogen bonds are present between the complex cations, nitrate anions and water mol-ecules. O-H⋯O hydrogen bonds between the uncoord-inated water mol-ecules lead to the formation of a four-membered ring water cluster, with a planar configuration. There were an additional five grossly disordered water mol-ecules in the asymmetric unit, which were removed by the subroutine SQUEEZE; these were were excluded in the calculation of the molecular weight, etc. π-π stacking inter-actions between the aromatic rings are also observed [centroid-centroid distances = 3.697 (2), 3.728 (2) and 3.761 (2) Å].

Tetra-kis(2-amino-4-methyl-pyridinium) cyclo-tetra-µ(2)-oxido-tetra-kis-[dioxido-vanadate(V)] tetra-hydrate.

The asymmetric unit of the title compound, (C(6)H(9)N(2))(4)[V(4)O(12)]·4H(2)O, contains half of a [V(4)O(12)](4-) anion, two 2-amino-4-methyl-pyridinium, (2a4mpH)(+), cations and two water mol-ecules. One water mol-ecule is disordered over two sets of sites with equal occupancies and the H atoms for this mol-ecule were not included in the refinement. The cation lies on an inversion center with four tetra-hedral VO(4) units each sharing two vertices, forming an eight-membered ring. In the crystal, the components are linked by inter-molecular N-H⋯O hydrogen bonds, forming a one-dimensional network along [100]. Further stabilization is provided by weak inter-molecular C-H⋯O hydrogen bonds. In addition, π-π stacking inter-actions with centroid-centroid distances of 3.5420 (18), 3.7577 (18) and 3.6311 (19) Šare observed.

2-Amino-pyrimidin-1-ium 4-methyl-benzene-sulfonate.

In the crystal structure of the title compound, C(4)H(6)N(3) (+)·C(7)H(7)O(3)S(-), inter-molecular N-H⋯O hydrogen bonds link the cations and anions into chains along [100]. Additional stabilization is provided by weak C-H⋯O hydrogen bonds. An inter-molecular π-π stacking inter-action with a centroid-centroid distance of 3.6957 (7) Šis also observed. The H atoms of the methyl group were refined as disordered over two sets of sites with equal occupancies.

Bis(2,6-diamino-pyridinium) bis-(pyridine-2,6-dicarboxyl-ato)zincate(II) monohydrate.

In the title hydrated mol-ecular salt, (C(5)H(8)N(3))(2)[Zn(C(7)H(3)NO(4))(2)]·H(2)O, the Zn(II) atom is coordinated by two O,N,O'-tridentate pyridine-2,6-dicarboxyl-ate dianions, generating a slightly distorted trans-ZnN(2)O(4) octa-hedral coordination geometry for the metal ion. In the crystal, a network of O-H⋯O, N-H⋯O and C-H⋯O hydrogen bonds involving the cations, anions and water mol-ecules results in a three-dimensional network.

Dimethyl 4-eth-oxy-1-(4-methyl-2-pyri-dyl)-5-oxo-2,5-dihydro-1H-pyrrole-2,3-dicarboxyl-ate.

In the title compound, C(16)H(18)N(2)O(6), the dihedral angle between the aromatic ring planes is 8.11 (6)°. One of the O atoms is disordered over two sites of equal occupancy. In the crystal structure, aromatic π-π stacking [centroid-to-centroid separation = 3.5503 (8) Å] helps to consolidate the packing.

(2-Amino-pyrimidine-κN)diaqua(pyridine-2,6-dicarboxyl-ato-κO,N,O)-nickel(II) monohydrate.

The reaction of Ni(NO(3))(2)·6H(2)O with pyridine-2,6-dicarboxylic acid, NaOH and 2-amino-pyrimidine in aqueous solution leads to the formation of the title complex, [Ni(C(7)H(3)NO(4))(C(4)H(5)N(3))(H(2)O)(2)]·H(2)O. The Ni(II) ion is coordinated by one N and two O atoms of the tridentate chelating pyridine-2,6-dicarboxyl-ate anion, one heterocyclic N atom of the 2-amino-pyrimidine ligand, and two water mol-ecules. The resulting geometry for the [NiN(2)O(4)] coordination environment can be described as distorted octa-hedral. One uncoord-inated water mol-ecule completes the asymmetric unit. Extensive O-H⋯O and N-H⋯O hydrogen-bonding inter-actions between the NH(2) group of 2-amino-pyrimidine, carboxyl-ate groups, and coordinated and uncoordinated water mol-ecules contribute to the formation of a three-dimensional supra-molecular structure.

Eth-oxy-carbonyl-methyl 3-(4-chloro-benzyl-idene)dithio-carbazate.

Mol-ecules of the title compound, C(12)H(13)ClN(2)O(2)S(2), are linked into centrosymmetric dimers by pairs of inter-molecular N-H⋯S hydrogen bonds. In the crystal structure, there are π-π stacking inter-actions between symmetry-related benzene rings with a centroid-centroid distance of 3.7305 (13) Å, a perpendicular distance between the planes of 3.2851 (9) Šand a slippage of 1.768 Å. The structure is further stabilized by weak inter-molecular C-H⋯O hydrogen bonds.