Titania-supported iridium catalysts for dehydrogenative synthesis of benzimidazoles

Strain Modified Oxygen Evolution Reaction Performance in Epitaxial, Freestanding, and Van Der Waals Manganite Thin Films

In perovskite complex oxides, the strain has been established as a promising approach for tuning the oxygen evolution reaction (OER) performance by the manipulated electronic structure and interaction/coupling. In this study, we have employed rigid epitaxial, flexible freestanding, and van der Waals La_2/3Sr_1/3MnO₃ (LSMO) to investigate the strain effects on OER, which are different in stress strength and range via lattice mismatch and curvature change. It was found that the OER performances as a function of strain exhibited volcano and monotonous trends in rigid and flexible LSMO, respectively. The findings suggest that distinguished oxygen activation energy in varied lattice fields also plays a crucial role in the epitaxial LSMO in contrast to the pure strain effect in the flexible LSMO. Our results not only fundamentally clarify the effort of strain but also technologically provide an effective route to engineer the electronic structure for modified OER performance by perovskite complex oxides.

UV-visible light-induced photochemical synthesis of benzimidazoles by coomassie brilliant blue coated on W-ZnO@NH2 nanoparticles

Heterogeneous photocatalysts proffer a promising method to actualize eco-friendly and green organic transformations. Herein, a new photochemical-based methodology is disclosed in the preparation of a wide range of benzimidazoles through condensation of o-phenylenediamine with benzyl alcohols in the air under the illumination of an HP mercury lamp in the absence of any oxidizing species catalyzed by a new photocatalyst W–ZnO@NH₂–CBB. In this photocatalyst, coomassie brilliant blue (CBB) is heterogenized onto W–ZnO@NH₂ to improve the surface characteristics at the molecular level and enhance the photocatalytic activity of both W–ZnO@NH₂ and CBB fragments. This unprecedented heterogeneous nanocatalyst is also identified by means of XRD, FT-IR, EDS, TGA-DTG, and SEM. The impact of some influencing parameters on the synthesis route and effects on the catalytic efficacy of W–ZnO@NH₂–CBB are also assessed. The appropriate products are attained for both the electron-withdrawing and electron-donating substituents in the utilized aromatic alcohols. Furthermore, preparation of benzimidazoles is demonstrated to occur mainly via a radical mechanism, which shows that reactive species such as ·O₂⁻, OH˙ and h⁺ would be involved in the photocatalytic process. Stability and reusability studies also warrant good reproducibility of the nanophotocatalyst for at least five runs. Eventually, a hot filtration test proved that the nanohybrid photocatalyst is stable in the reaction medium. Using an inexpensive catalyst, UV-vis light energy and air, as a low cost and plentiful oxidant, puts this methodology in the green chemistry domain and energy-saving organic synthesis strategies. Finally, the anticancer activity of W–ZnO nanoparticles is investigated on MCF7 breast cancer cells by MTT assay. This experiment reveals that the mentioned nanoparticles have significant cytotoxicity towards the selected cell line.

A new photochemical route is disclosed in the preparation of a wide range of benzimidazoles in air under the illumination of an HP mercury lamp in the absence of any oxidizing species catalyzed by heterogenized W–ZnO@NH₂–CBB.

Selective photocatalytic oxidation of aromatic alcohols to aldehydes with air by magnetic WO3ZnO/Fe3O4. In situ photochemical synthesis of 2-substituted benzimidazoles

Recently, visible light-driven organic photochemical synthesis has been a pioneering field of interest from academic and industrial associations due to its unique features of green and sustainable chemistry. Herein, WO3ZnO/Fe3O4 was synthesized, characterized, and used as an efficient magnetic photocatalyst in the preparation of a range of 2-substituted benzimidazoles via the condensation of benzyl alcohol and o-phenylenediamine in ethanol at room temperature for the first time. The key feature of this work is focused on the in situ photocatalytic oxidation of benzyl alcohols to benzaldehydes under atmospheric air and in the absence of any further oxidant. This new heterogeneous nanophotocatalyst was characterized via XRD, FT-IR, VSM and SEM. Short reaction time, cost-effectiveness, broad substrate scope, easy work-up by an external magnet, and excellent product yield are the major advantages of the present methodology. A number of effective experimental parameters were also fully investigated to clear broadness and generality of the protocol.