Tetrakis [<Emphasis Type="Italic">N</Emphasis>-(2-pyridyl) sulfonamide] di palladium: synthesize,X-ray diffraction,antibacterial properties and as a novel binuclear Pd-complex for coupling reactions

The N-(2-pyridyl) 4-toluene sulfonamide as a free ligand (PTS) was prepared from the reaction of 2-amino pyridine and 4-toluenesulfonyl chloride in the presence of potassium hydroxide solution 1 M as a base and THF was used as a solvent. The complex tetrakis [N-(2-pyridyl) sulfonamide] di palladium (1) (Pd₂L₄) was also prepared from the reaction of PdCl₂(CH₃CN)₂ using (PTS) in the presence of NaOH 0.5 M and its application in Heck and Suzuki reactions. This complex consists of a binuclear unit consisting of four ligands linked to two palladium atoms via the nitrogen of pyridines ring and the nitrogen of sulfonamides. These compounds were confirmed by FT-IR and ¹H NMR spectroscopy. Moreover, the structure of the complex was studied by single-crystal X-ray diffraction method. The green crystal of Pd₂L₄ [L = N-(2-pyridyl) sulfonamide](1) was found to crystallize in the monoclinic space group C2/c with a = 18.2013(19), b = 19.7544(16), c = 17.2898(19) Å, β = 120.179(8) °; V = 5374.0(9) ų; Z = 4; the final R ₁ = 0.0894, wR ₂ = 0.1754 (or 5867 observed reflections and 318 variables). The Pd–Pd distance is 2.567(2) Å. In addition, PTS and Pd₂L₄ presented different antibacterial behaviors. The free ligand was active against Staphylococcus aureus and Escherichia coli, but the complex was inactive against them.     

A cyclometalated diplatinum complex containing 1,1′-bis(diphenylphosphino)ferrocene as spacer ligand: Antitumor study

Cyclometalated platinum(II) complex [Pt(C^N)Cl(dmso)], 1, in which C^N = N(1),C(2′)-chelated deprotonated 2-phenylpyridine and dmso = dimethylsulfoxide, was reacted with 1 equiv of 1,1′-bis(diphenylphosphino)ferrocene, dppf, to give the cyclometalated diplatinum(II) complex [Pt₂(C^N)₂Cl₂(μ-dppf)], 2, along with 0.5 equiv of unreacted dppf. However, the related reaction with 0.5 equiv of dppf produced complex 2 in pure form. Complex 2 in solution was fully characterized by using multinuclear NMR spectroscopy (¹H, ¹³C, ³¹P, and ¹⁹⁵Pt) and a number of 2D NMR experiments. The structure of complex 2 in solid state was determined by X-ray crystallography showing that the bridging dppf ligand is arranged close to “antiperiplanar staggered” conformation. Cytotoxicity of the complex 2 was studied in three human cancer cell lines derived from ovarian carcinoma(CH1), lung carcinoma(A549), and colon carcinoma (SW480) by means of the MTT assay (MTT = 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2H-tetrazolium bromide).     

Methylmercury in marine fish from Malaysian waters and its relationship to total mercury content

The study evaluated methylmercury concentrations, the methylmercury to total mercury ratio (%MeHg) and their correlations in ten fish species from different trophic levels. Methylmercury levels in fish studied were in the range of 0.007 to 0.914 µg g^?1 wet wt. Muscle tissue of predatory fish contained significantly (p < 0.05) higher content of methylmercury than non-predatory fish. The methylmercury to total mercury ratio ranged from 49.1% to 87.5%, with the highest ratio in predatory fish. This ratio was always higher in muscle tissue compared to the liver tissues, indicating tissue-specific binding and accumulation of methylmercury in the muscle. All the fish species showed strong positive correlation between methylmercury and total mercury levels (R ²> 0.86). Except for long tail tuna and short-bodied mackerel, all fish species showed lower methylmercury levels and estimated weekly intake as compared to the maximum values established by US FDA (of 0.5 µg g^?1) and by FAO/WHO (1.5 µg kg^?1 bodyweight), respectively. This study showed that the percentage of methylmercury is rather high in fish and fish represents the major source of this toxic mercury form to the local population.     

Effect of Curcuma longa tuber powder extract on size of silver nanoparticles prepared by green method

Biosynthesis of noble metal nanoparticles is a vast developing area of research. In the present study, silver nanoparticles (Ag-NPs) were synthesized from aqueous silver nitrate through a simple and biosynthetic route using water extract of Curcuma longa (C. longa) tuber powder, which acted simultaneousl as a reductant and stabilizery. The as-prepared samples are characterized using UV–Visible, XRD, TEM, SEM, EDXF, and FT-IR techniques. The formation of Ag-NPs is evidenced by the appearance of the signatory brown color of the solution and UV–vis spectra. Formation of Ag/C. longa was determined by UV–Vis spectroscopy where surface plasmon absorption maxima can be observed at 457–415 nm from the UV–Vis spectrum. The XRD analysis shows that the Ag-NPs are of a face-centered cubic structure. Well-dispersed Ag-NPs with anisotropic and isotropic morphology for 5, 10, and 20 mL of C. longa water extract having a size less than 10 nm are seen in TEM images. The optimum volume extraction to synthesize smallest particle size was 20 mL with mean diameter and standard division 4.90 ± 1.42 nm. FT-IR spectrum indicates the presence of different functional groups in capping the nanoparticles with C. longa. The zeta potential analysis results indicated that the charge of C. longa was negative and increased in Ag/C. longa emulsion with increasing of volumes of extract used (10–20 mL). The most needed outcome of this work will be the development of value-added products from C. longa for biomedical and nanotechnology-based industries.     

Investigation of antibacterial properties silver nanoparticles prepared via green method

ABSTRACT: BACKGROUND: This study aims to investigate the influence of different stirring times on antibacterial activity of silver nanoparticles in polyethylene glycol (PEG) suspension. The silver nanoparticles (Ag-NPs) were prepared by green synthesis method using green agents, polyethylene glycol (PEG) under moderate temperature at different stirring times. Silver nitrate (AgNO3) was taken as the metal precursor while PEG was used as the solid support and polymeric stabilizer. The antibacterial activity of different sizes of nanosilver was investigated against Gram-positive [Staphylococcus aureus] and Gram-negative bacteria [Salmonella typhimurium SL1344] by the disk diffusion method using Mueller-Hinton Agar. RESULTS: Formation of Ag-NPs was determined by UV-vis spectroscopy where surface plasmon absorption maxima can be observed at 412-437 nm from the UV-vis spectrum. The synthesized nanoparticles were also characterized by X-ray diffraction (XRD). The peaks in the XRD pattern confirmed that the Ag-NPs possessed a face-centered cubic and peaks of contaminated crystalline phases were unable to be located. Transmission electron microscopy (TEM) revealed that Ag-NPs synthesized were in spherical shape. The optimum stirring time to synthesize smallest particle size was 6 hours with mean diameter of 11.23 nm. Zeta potential results indicate that the stability of the Ag-NPs is increases at the 6 h stirring time of reaction. The Fourier transform infrared (FT-IR) spectrum suggested the complexation present between PEG and Ag-NPs. The Ag-NPs in PEG were effective against all bacteria tested. Higher antibacterial activity was observed for Ag-NPs with smaller size. These suggest that Ag-NPs can be employed as an effective bacteria inhibitor and can be applied in medical field. CONCLUSIONS: Ag-NPs were successfully synthesized in PEG suspension under moderate temperature at different stirring times. The study clearly showed that the Ag-NPs with different stirring times exhibit inhibition towards the tested gram-positive and gram-negative bacteria.