"Synthesis and characterization of new SILVER(I) coordination polymers incorporating a BIS(TRIAZOLYL)-type ligand "

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Catalytic Effect of Photoluminescent Zinc Oxide Nanoparticles Formed in the Presence of Quaternary Ammonium Salts

The comparative effect of two quaternary ammonium salts from 1,2-bis(4-pyridyl)ethane (PyQAs), namely N,N′-diphenacyl-1,2-bis(4-pyridinium)ethane dibromide (PyQAs1) and N,N′-di(p-methoxyphenacyl)-1,2-bis(4-pyridinium)ethane dibromide (PyQAs2), upon the size and photoluminescence of zinc oxide nanoparticles (ZnO NPs) was investigated. The formation of ZnO NPs took place in the presence of variable amounts of the two PyQAs species (1, 2.5, and 5%), according to the chemical precipitation of zinc(II) acetate with potassium hydroxide in ethanol under reflux. The obtained ZnO NPs were structurally characterized by means of X-ray powder diffraction, infrared, and Raman spectroscopy. The fluorescence of all supernatant solutions, observed under ultraviolet light, determined us to make an investigation of the solutions by means of liquid chromatography coupled with electrospray ionization mass spectrometry (LC-MS-ESI) in order to elucidate the identity of the newly formed fluorescent species. Such an occurrence thus allowed the invocation of the catalytic effect of zinc(II) ions towards the organic transformation of both nonfluorescent PyQAs surfactants into new fluorescent organic species

Complexes of copper(I) thiocyanate with monodentate phosphine and pyridine ligands and the P(,N)-donor diphenyl(2-pyridyl)phosphine

Copper(I) thiocyanate derivatives were prepared by the reaction of CuNCS with pyridine (py) and tertiary monophosphine ligands [PR3 in general; in detail: PPh3, triphenylphosphine, P(4-FPh)3, tris(4-fluorophenyl)phosphine)], as well as the potentially bidentate ligand diphenyl(2-pyridyl)phosphine (PPh2py). Mechanochemical methods were used in some cases to investigate stoichieometries that were not easily accessible by conventional solution syntheses. Three forms of the resulting adducts of CuNCS/PR3/py-base (1:3–n:n) stoichiometry―all containing four-coordinate copper(I) atoms and monodentate N-thiocyanate groups―were confirmed crystallographically. Mononuclear arrays are defined for [(PPh2py)3–n(py)nCuNCS], n = 0, 1, 2, the monodentate thiocyanate being N-coordinated in all; two polymorphs are observed for the n = 2 complex, both crystallizing in monoclinic P21 (Z = 2) cells with similar cell dimensions, but with aromatic components eclipsed about the Cu–P bond in the PPh3 complex, and staggered in the PPh2py complex. Bridging thiocyanate groups are found in the 1:1:1 CuNCS/PPh2py/2-methylpyridine (mpy) and P(4-FPh)3/mpy complexes, wherein centrosymmetric dimers with eight-membered central rings are obtained: [(R3P)(mpy)Cu(NCS)2Cu(PR3)(mpy)], as is also the case in the parent 1:2 CuNCS/PPh2py adduct [(pyPh2P)2Cu(NCS)2Cu(PPh2py)2]. For the 1:1:1 CuNCS/P(4-FPh)3/py and PPh3/Brmpy (Brmpy = 3-bromo-4-methylpyridine) adducts, and, likely, CuNCS/PPh2py/py (1:1:1), single-stranded polymers of the form [···Cu(NCS)(PR3)(py-base)(Cu)···](∞|∞) with linearly bridging NCS ligands were obtained. Some derivatives, representative of all forms, display medium to strong green to blue luminescence when excited with radiation at 365 nm. The 31P CPMAS NMR spectroscopic data clearly differentiate the inequivalent phosphorus positions within each system, showing a wide range of 1J(31P,63/65Cu) values ranging from 965 Hz for [Cu(NCS)(PPh2py)3] to 1540 Hz for dimeric [(4-FPh)3P(mpy)Cu(NCS)2Cu(P(4-FPh)3)(mpy)], reflecting the large variations in the Cu–P bond length

Oligo-nuclear silver thiocyanate complexes with monodentate tertiary phosphine ligands, including novel ‘cubane’ and ‘step’ tetramer forms of AgSCN : PR3 (1 : 1)4

Adducts of a number of tertiary pnicogen ligands ER3 (triphenyl-phosphine and -arsine (PPh3,AsPh3), diphenyl,2-pyridylphosphine (PPh(2)py), tris(4-fluorophenyl) phosphine (P(C6H4-4F)(3)), tris(2-tolyl)phosphine (P(o-tol)(3)), tris(cyclohexyl) phosphine (PCy3)), with silver(I) thiocyanate, AgSCN are structurally and spectro-scopically characterized. The 1 : 3 AgSCN : ER3 complexes structurally defined (for PPh3, AsPh3 (diversely solvated)) take the form [(R3E)(3)AgX], the thiocyanate X = NCS being N-bound, thus [(Ph3E)Ag(NCS)]. A 1 : 2 complex with PPh(2)py, takes the binuclear form [(pyPh(2)P)(2)Ag(SCN NCS)Ag(PPh(2)py)(2)] with an eight-membered cyclic core. 1 : 1 complexes are defined with PPh(2)py, P(o-tol)(3) and PCy3; binuclear forms [(R3P) Ag((SCN)(NCS))Ag(PR3)] are obtained with P(o-tol)(3) (two polymorphs), while novel isomeric tetranuclear forms, which may be envisaged as dimers of dimers, are obtained with PPh(2)py, and, as further polymorphs, with PCy3; these latter may be considered as extensions of the 'cubane' and 'step' forms previously described for [(R3E)AgX](4) (X = halide) complexes. Solvent-assisted mechanochemical or solvent-assisted solid-state synthesis methods were employed in some cases, where complexes could not be obtained by conventional solution methods, or where such methods yielded a mixture of polymorphs unsuitable for solid-state spectroscopy. The wavenumbers of the nu(CN) bands in the IR spectra are in broad agreement with the empirical rule that distinguishes bridging from terminal bonding, but exceptions occur for compounds that have a double SCN bridged dimeric structure, and replacement of PPh3 with PPh2py apparently causes a significant decrease in.(CN) to well below the range expected for bridging SCN in these structures. P-31 CP MAS NMR spectra yield additional parameters that allow a correlation between the structures and spectra

Sono-Biosynthesis and Characterization of AuNPs from Danube Delta Nymphaea alba Root Extracts and Their Biological Properties

Root extracts from Danube Delta Nymphaea alba were used to prepare gold nanoparticles (AuNPRn) by reducing HAuCl4 at different pHs (6.4–8.4) using ultrasonic irradiation: an easy, cheap, eco-friendly and green approach. Their antibacterial and anticancer activities were evaluated against Staphylococcus aureus and Escherichia coli, and A2780 ovarian cancer cells, respectively. The AuNPRn were characterized concerning their phytoconstituents (polyphenols, flavonoids and condensed tannins) and gold content. All of the nanoparticles were negatively charged. AuNPRn exhibited a hydrodynamic size distribution ranging from 32 nm to 280 nm, with the larger nanoparticles being obtained with an Au/root extract ratio of 0.56, pH 7 and 10 min of sonication (AuNPR1), whereas the smallest were obtained with an Au/root extract ratio of 0.24, pH 7.8 and 40 min of sonication (AuNPR4). The TEM/SEM images showed that the AuNPRn had different shapes. The ATR-FTIR indicated that AuNPRn interact mainly with hydroxyl groups present in the polyphenol compounds, which also confirm their high antioxidant capacity, except for AuNPR2 obtained at pH 6.4. Among the AuNPRn, the smallest ones exhibited enhanced antimicrobial and anticancer activities