Bio-directed Synthesis of Sm2O3 NPs by Hibiscus Syriacus Ardens flower extract as an effective catalyst in the preparation of benzimidazole derivatives

Double bloom purple Rose of Sharon, with the scientific name of Hibiscus Syriacus Ardens in the family of Malvaceae, was collected from Mazandaran, Iran in spring, dried in the shade, and powdered. The powdered flower material was extracted in ethanol (70% (V/V)). Samarium oxide nanoparticles (Sm2O3 NPs) were synthesized by using the Rose of Sharon flower extract. The morphology and structure of NPs were determined by FT-IR, X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), and energy dispersive spectra (EDS). Then, biosynthesized Sm2O3 NPs was used as a highly efficient catalyst for the synthesis of benzimidazole derivatives. These compounds were synthesized by the reaction of o-phenylenediamine and some sugars in the presence of Sm2O3 NPs (5 mol%) in ethanol 70%. The assigned structure was further established by CHN analyses, NMR, and FT-IR spectra. The catalyst was simply recovered, washed with ethanol, and reused 4 times without significant loss of activity.