Dra. Gerli-Candia, Lorena

A theoretical quantum study of the organophosphorus compound with formula C10H19OPCl2 (MEPCL2) was carried out. The results of the calculations show excellent agreement between experimental and computed frequencies evaluated at the B3LYP/6-311++G(d,p) level of theory. A study of the electronic properties, such as excitation energies and wavelengths were performed employing the time-dependent DFT (TD-DFT) method. Global a chemical reactivity of MEPCL2 was analyzed through global reactivity descriptors, while its local reactivity was analyzed by mean maps of the electrostatic potential. Also, the orbital energies values suggest that a charge transfer is occurring within the molecule.

Nanoparticles (NPs) of new fluoride (SrF2 and MgF2) nanocompounds were synthesized by the simple chemical method of precipitation in ethanol. Synthesis of the strontium fluoride (SrF2)-magnesium oxide (MgO) nanocomposite was achieved through the ultrasonic method. These prepared nanopowders were characterized through Fourier transform infrared (FT-IR) spectroscopy, ultraviolet–visible (UV–Vis) spectroscopy, Powder X-ray Diffraction (PXRD) and Scanning Electron Microscopy (SEM). FT-IR confirmed the purity of the synthesized fluoride NPs by evaluation of the vibrations, and UV–Visible showed the intense absorption peaks of NPs. PXRD analysis indicated the average of particle size, and SEM demonstrated a nearly spherical morphology of the NPs. The antibacterical properties of the nanopowders on Staphylococcus Aureus, Bacillus Subtilis and E. Aklay bacteria were studied, with the strongest effect by the magnesium fluoride (MgF2) NPs and the SrF2-MgO nanocomposite.

Two new phosphorus complexes, potassium trichlorothiocyanophosphate (III) (PTCTCP; K[PCl3(SCN)]) and potassium trichlorocyanophosphate (III) (PTCCP; K[PCl3(CN)]) were synthesized from the reaction of KSCN and KCN, respectively, with PCl3. The chemical formulas and compositions of these compounds were determined by elemental analysis and spectroscopic methods, such as phosphorus-31 nuclear magnetic resonance (NMR) spectroscopy (31P-NMR), Fourier transform infrared (FTIR) spectroscopy, ultraviolet-visible (UV-Vis) spectroscopy and mass spectrophotometry. All of the theoretical calculations and determinations of the properties of these compounds were performed as part of the Amsterdam Density Functional (ADF) program. Excitation energies were assessed using time-dependent perturbation density functional theory (TD-DFT). In addition, the molecular geometry was optimized and the frequencies and excitation energies were calculated using standard Slater-type orbital (STO) basis sets with triple-zeta quality double plus polarization functions (TZ2P) for all of the atoms. The assignment of the principal transitions and total densities of state (TDOS) for orbital analysis were performed using the GaussSum 2.2 program.

Little is known regarding the use and ambient levels of pesticides in Chilean agricultural regions. Chlorpyrifos (CPF) is one of the most used active ingredients in Chile and in the world. However, few investigations have been conducted to understand its environmental distribution and fate. In this study, PUF disk passive air samples were deployed during ~one year in two areas, Angol (5 sites) and Villarrica (2 sites), in the Araucanía Region. The concentration in air of CPF ranged from ten to thousands of pg m-3 (~20e14 600). The highest CPF concentrations were detected at the Angol sites (~14 600 pg m3) during period 2 (AugusteDecember 2008). These results were higher by a factor of ~10e15 than those detected in Villarica sites (~2000 pg m3) in period 1 (AprileJuly 2008). Seasonal CPF variations were observed, at both sites, within the sampling periods. Air back trajectory analyses showed that air masses from nearby agricultural zones contributed most of the CPF detected in Angol sites when the wind speed was low and at Villarrica when those sources were likely located north of the VMA site. These results provide initial data for CPF in the Chilean atmosphere and contribute new information to understanding distribution of CPF in Chilean environments.