Research on Chemical Intermediates

A highly dispersed Cr6+-oxide species on silica (Cr/SiO2) was found to act as an efficient photocatalyst for the selective oxidation of CO into CO2 with O2 in the presence of H2 under visible (λ>420 nm) or solar light irradiation at 293 K. UV-Vis, photoluminescence and FT-IR investigations revealed that the selective reactivity of the photoexcited tetrahedral Cr6+-oxide species ([Cr5+−O−]*) with CO, as well as the high reactivity of the photoreduced Cr6+-oxide species (Cr4+-oxide species) with O2 both play significant roles in this reaction.

Penicillium sp. is among fungi that can infect cereals, maize, and other foodstuffs, causing not only important yield losses but also contamination of the crops by toxins production, which make them unsafety for consumption. In this context, the main objective of this study is the development of clay/essential oil formulations against this type of fungus. Double-layer hydroxides (LDHs) and Ghassoul were chosen as clays, and Thyme as an essential oil and its active principle, thymol. The LDHs and Ghassoul materials underwent purification and activation treatments to increase their compatibility with the chosen essential oil. The different materials obtained were characterized by XRD and FTIR. The chemical compositions of the EOs were analyzed by GC–MS chromatography. The main constituents of Thyme oil founded were thymol (67.13%), ρ-cymene (4.85%), Z-Caryophyllene (1.77%) and γ-terpinene (2.74%). The adsorption of thymol on the different materials developed: activated Ghassoul (Gh-A), Hydrotalcite (HT3), and LDH (ZnAl-CO3), showed that the adsorption isotherms can be satisfactorily described by the Langmuir model. Also, the modeling of the adsorption kinetics revealed its conformity to the pseudo-second order model for the different materials. As a result, the adsorption capacity of thymol increases in the following order: ZnAl-CO3, HT3, and Gh-A. The formulations made from the different clays allowed for the preparation of an effective and useful fungicide for wheat storage. The in vitro antifungal activities were tested against the strain Penicillium sp. The results obtained revealed that the formulations based on Gh-A and LDHs retained their antifungal activity even after 5 months of storage. Therefore, in order to evaluate the potential of the formulations on cereals storage (wheat storage case), in vitro antifungal tests with the Gh-A/Thyme formulation were performed on four types of wheat (sterile, non-sterile, dried, and washed then dried wheat). These experiments demonstrated that sterile and washed-dried wheat had a significant inhibition against Penicillium sp. growth even after six months of storage.

Three novel 1,8-naphthalimide derivatives containing indole and indoline were synthesized through Fischer indole synthesis, reduction, and alkylation. Two reference dyes with similar structures to the three novel dyes were also prepared. The absorption and fluorescence spectra of these dyes in a variety of solvents were investigated. In addition, fluorescence of these dyes in solid state was also measured. Intramolecular charge transfer was confirmed within the new dyes by virtue of shifts in emission maximum with increasing solvent polarity. Intermolecular close contacts and lateral intermolecular hydrogen bonding interactions between neighboring columns lead to fluorescence wavelength shift, short in the solution and long in the solid state.

Ligand effects on ethene insertion into a series of cationic phenylpalladium complexes with diverse bidentate phosphine ligands were studied by using the density functional methods. For the complexes with n-membered ring ligands (n = 4–6), a correlation was found between the ring size and the insertion barrier. This behavior was explained by considering the P—Pd—P bond angle. In the case of complexes with ligands of different rigidity, almost no difference was found for the insertion barriers. Furthermore, the bidentate phosphine ligand was systematically substituted by Me, t-Bu, F and Ph groups. It was found that the electron-donating substituents increased the insertion barrier, whereas the electron-withdrawing groups decreased it. The substantial increase of insertion barrier by the t-Bu group indicated that steric effect also had great effect on the migratory insertion.

Recently, completely incinerable N,N-dihexyloctanamide (DHOA) has been identified as a promising alternative to tri-n-butyl phosphate for the reprocessing of spent nuclear fuels. The present work deals with the pulsed radiolytic investigation on the reactions of DHOA with the radicals produced in the radiolysis of nitric acid and dodecane medium. The rate constants of the reactions of DHOA with solvated electron, nitrate radical and dodecane radicals have been measured and the transients have been characterized. In addition, the reactions of DHOA transients have also been studied.

Competitive kinetic experiments were performed for the reactions of H atoms with HCOOH and DCOOD in aqueous solution. Excellent Arrhenius behavior is represented by log(k/M-1 s-1) = (11.6 ± 0.2) - (34.0 ± 1.1) kJ mol-1/2.303RT ) for HCOOH, log(k/M-1 s-1) = (11.8 ± 0.2) - (39.8 ± 1.2) kJ mol-1/2.303RT ) for DCOOD. Kinetic isotope effects are discussed in terms of transition state theory, supported by ab initio calculations, and in comparison with previous results for the abstraction from the formate ion.