Influence of C6_{6}H4_{4}(OH)2_{2} isomers on water disinfection by photocatalysis: a computational study

Solar disinfection by photocatalysis is one of the promising methods used for drinking water disinfection. It leads to the destruction of bacteria like $Escherichia$ $Coli$ ($E.$ $Coli$). In this paper, we compare our theoretical results with experimental ones done previously by A.G. Rinc\'on and his colleagues concerning the order of decay of C$_{6}$H$_{4}$(OH)$_{2}$ isomers in the presence of titanium dioxide TiO$_{2}$, and show the influence of optical properties of those molecules on $E.$ $Coli$ inactivation. According to the adsorption energy parameter, we find that catechol has the highest adsorption degree on titanium dioxide, followed by resorcinol, and finally hydroquinone. Three dihydroxybenzene isomers absorb photons belonging to ultraviolet (UV) range. The lowest absorption energies of resorcinol, catechol and hydroquinone are respectively 3.42, 4.44 and 4.49 eV.Comment: 7 pages, 3 figures, 1 tabl

A vibrational circular dichroism implementation within a Slater-type-orbital based density functional framework and its application to hexa- and hepta-helicenes

We describe the implementation of the rotational strengths for vibrational circular dichroism (VCD) in the Slater-type orbital based Amsterdam Density Functional (ADF) package. We show that our implementation, which makes use of analytical derivative techniques and London atomic orbitals, yields origin independent rotational strengths. The basis set dependence in the particular case of Slater-type basis functions is also discussed. It turns out that the triple zeta STO basis sets with one set of polarization functions (TZP) are adequate for VCD calculations. The origin- dependence of the atomic axial tensors is checked by a distributed origin gauge implementation. The distributed and common origin gauge implementations yield virtually identical atomic axial tensors with the Slater-type basis sets employed here, proving that our implementation yields origin independent rotational strengths. We verify the implementation for a set of benchmark molecules, for which the dependence of the VCD spectra on the particular choice of the exchange–correlation functional is studied. The pure functionals BP86 and OLYP show a particularly good performance. Then, we apply this approach to study the VCD spectra of hexa- and hepta- helicenes. In particular we focus on relationships between the sign of the rotational strengths of the two helicenes

Magnetic and Nanostructural Properties of Cobalt–Zinc Ferrite for Environmental Sensors

In this study, we compare nanoparticles (NPs) of Co0.5Zn0.5Fe2O4 spinel ferrite produced by a novel simple synthetic technique with those made by standard co-precipitation, sol-gel, and hydrothermal methods. The novel process is based on the addition of a very small amount of ethanol (only 2 vol% in water with a low ethanol:metals molar ratio of 0.5:1, not a co-solvent) during co-precipitation to synthesize a nanopowder, which formed single-phase magnetic spinel ferrite when heated at 700 !C. This technique produced cobalt–zinc ferrite NPs smaller than those formed by the other methods, with an average crystallite size of 17 nm calculated from X-Ray Diffraction and NPs sizes around 30 nm observed by scanning electron microscopy. A surface area of 32 m2/g, and a total pore volume of about 0.56 cm3/g, were determined by the BET isotherm. The best catalytic capabilities for converting ethanol vapor to CO, CO2, and H2O, as well as magnetic properties, were obtained for Co0.5Zn0.5Fe2O4 synthesized by the ethanol-assisted co-precipitation. The ethanol conversion rate rapidly increased above 175 !C, and the total conversion of ethanol was achieved at a relatively low temperature of 230 !C. This sample also had the largest magnetization of 58.2 A m2 kg"1 at 3 T, and a very small, near superparamagnetic, coercivity

Determination of absolute configuration using vibrational circular dichroism spectroscopy: The chiral sulfoxide 1-(2-methylnaphthyl) methyl sulfoxide

We report the determination of the absolute configuration (AC) of the chiral sulfoxide, 1-(2-methylnaphthyl) methyl sulfoxide, 1, using vibrational circular dichroism (VCD) spectroscopy. The VCD of 1 has been measured in the mid-IR spectral region in CCl4 solution. Analysis employs the ab initio DFT/GIAO methodology. DFT calculations predict two stable conformations of 1, E and Z, Z being lower in energy than E by <1 kcal/mol. In both conformations the S-O bond is rotated from coplanarity with the naphthyl moiety by 30-40°. The predicted unpolarized absorption ("IR") spectrum of the equilibrium mixture of the two conformations permits assignment of the experimental IR spectrum in the mid-IR spectral region. The presence of both E and Z conformations is clearly evident. The VCD spectrum predicted for S-1 is in excellent agreement with the experimental spectrum of (-)-1, unambiguously defining the AC of 1 as R(+)/S(-)