Photocatalytic properties of Cu-containing ZnO nanoparticles and their antifungal activity against agriculture-pathogenic fungus.

In this work, nanoparticles (NPs) of ZnO, ZnO with Cu incorporated at 2 and 30 wt%, and CuO were prepared by the hydrothermal method. X-ray diffraction pattern (DRX) analysis showed that ZnO with high Cu incorporation (30 wt%) generates the formation of a composite oxide (ZnO/CuO), while X-ray photoelectron spectroscopy (XPS) of the Cu (2 wt%) sample indicated that Cu is incorporated as a dopant (ZnO/Cu2%). The samples with Cu incorporated had enhanced visible light absorption. Methyl orange (MO) dye was used to perform photocatalytic tests under UV radiation. The antifungal activity of the NPs was tested against four agricultural phytopathogenic fungi: Neofusicoccum arbuti, Alternaria alternata, Fusarium solani, and Colletotrichum gloeosporioides. The ZnO/Cu2% nanoparticles showed adequate photocatalytic and high antifungal activity in comparison to pure oxides and the composite sample.

Aqueous-phase synthesis of nanoparticles of copper/copper oxides and their antifungal effect against Fusarium oxysporum.

Different copper based-materials have been used for controlling some fungal and bacterial pathogens. However, the antifungal activity of the copper-based materials depends on different parameters, such as the crystal phase, synthesis route, and size of the particles. Herein a facile route synthesis method of Cu/CuxO-NPs was achieved through the aqueous phase. The influence of NaBH4 concentration on the phase composition was studied. The synthesized Cu/CuxO-NPs were characterized by X-Ray diffraction (XRD), Scanning electron microscopy (SEM), transmission electron microscopy (TEM) and dynamic light scattering. Five Cu/CuxO-NPs with different phase composition and nanoparticle size were obtained. The antifungal activity of the synthesized Cu/CuxO-NPs was studied in vitro against Fusarium oxysporum. The results indicate that a high percent of inhibition of radial growth (IGR) was obtained with NPs, which have a higher proportion of Cu2O phase and relatively smaller size particles. Furthermore, hypha morphology, membrane damage and production of reactive oxygen species (ROS) was evaluated with SEM and confocal microscopy.

Effects of the 3- and 4-methoxy and acetamide substituents and solvent environment on the electronic properties of N-substituted 1,8-naphthalimide derivatives.

The photophysical properties of polar molecules in solution with an intramolecular charge-transfer effect in the excited state depend strongly on the polarity and proticity of the solvents. UV-visible spectra of 1,8-naphthalimide and some N-substituted derivatives in acetic acid, acetonitrile, dichloromethane, and p-dioxane were carried out. Several molecular cluster geometries formed with N-substituted 1,8-naphthalimide derivatives and a large set of random positioning of some solvent molecules in their environment were optimized by a semiempirical method. It provided a complete screening of possible solute-solvent configurations and resulted in a multiple minima hypersurface of the supramolecular systems. With such local minima energies, the main thermodynamic association functions were found. They also provided selected cluster geometries for calculations of vertical electronic transitions with a time-dependent density functional theory (TD-DFT), if the lowest energy structures were considered. Calculated vertical electronic transition energies at the TD-DFT level were compared with experimental data. The experimental absorption UV-visible spectra for the six compounds in the four solvents were performed in our laboratory. Moreover, X-ray photoelectron spectroscospy of the 1,8-naphthalimide was carried out in the ICP-CSIC laboratory. Thermodynamic function values show different association energies between each solvent and the molecules, in correlation with the possibility of hydrogen bond formation and the polarity and dielectric constant of the solvents. The 3- and 4-acetamide 1,8-naphthalimide derivatives have the highest conformer number and the most negative Gibbs free association energy values for a determined solvent. This indicates the importance of the entropic factors.

π-Bonding contribution to restricted internal rotations in saccharides.

Extensive semiempirical SCF-MO calculations confirm that the exo-anomeric effect in methyl O-, N- and S-glycosides deals with an interaction of π-character along the C1 (SINGLE BOND)Y1 bond in a X5 (SINGLE BOND)C1 (SINGLE BOND)Y1 (SINGLE BOND)Me moiety (where X = O, S; Y = O, NH, S). The bond-order between orbitals of pπ symmetry on C1 and Y1 serves as a measure of all significant molecular orbital interactions responsible for the exo-anomeric stabilization. The set of simpler compounds X(SINGLE BOND)CH2 (SINGLE BOND)Y (X = OH, SH, SeH, TeH; Y = OH, SH, SeH, TeH, NH2 ) on which the anomeric effect has been well studied was also calculated and it is noticeable that the π-bond-orders accord with the results of other analyses of the ab initio wave function accounting for the anomeric effect. Although the AM1 and the PM3 parameterizations of MNDO do not accurately reproduce the anomeric effect energetic, they do reproduce accordingly the expected variations in the molecular conformations of complex carbohydrates, and thus it follows that there are maximal π-bond-orders for the synclinal arrangement around the C1 (SINGLE BOND)Y1 bond. In addition, the π-bond-orders show the same behavior for conformational preferences around the C1 (SINGLE BOND)C'1 and the C5 (SINGLE BOND)C6 bonds in methyl C-glycosides and in the hydroxymethyl group of α-D-glucose, respectively. © 1996 by John Wiley & Sons, Inc.

Theoretical models for the conformations and the protonation of triacetonamine.

In this paper we propose theoretical models for the conformations of triacetonamine and protonated triacetonamine (Vincubine, an anticancer chemotherapeutic agent) developed by quantum and molecular mechanics techniques. We discuss the theoretical factors which are involved in the stabilization of the conformations calculated by the MNDO, MM2 and COPEANE methods and show the relative percent abundance of each molecular shape. Graphic representations of the conformers are depicted.