A chromium-containing metal-organic framework (MOF), MIL-101 (Chromium(III) benzene-1,4-dicarboxylate), was used to catalyze the one pot, three component synthesis of some 2,4,5-trisubstituted imidazoles under solvent-free conditions. The advantages of using this heterogeneous catalyst include short reaction time, high yields, easy and quick isolation of catalyst and products, low amount of catalyst needed, and that the addition of solvent, salt, and additives are not needed. This catalyst is highly efficient and can be recovered at least 5 times with a slight loss of efficiency. The structure of the metal-organic frameworks (MOF) was confirmed by X-ray diffraction (XRD) and field emission scanning electron microscopy (FESEM). Fourier transform infrared spectroscopy (FTIR) and proton nuclear magnetic resonance (HNMR) were performed to confirm some of the synthesized products. Experimental data indicated that the optimum amount of catalyst was 5 mg for benzil (1 mmol), 4-chlorobenzaldehyde (1 mmol), and ammonium acetate (2.5 mmol), and the synthetic route to the various imidazoles is performed in 10 min by 95% yield, an acceptable result rivalling those of other catalysts.

In the present work, we have reported the straightforward preparation of a novel MOF heterostructure with the BaWO4 under mild conditions. In order to confirm the structure of the synthesized composite we utilized different characterization techniques including Scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform infrared (FT-IR), Diffuse reflectance spectroscopy (DRS) and Photoluminescence (PL). To investigating and addressing the photocatalytic properties of the prepared system we have selected the Methyl Orange (MO) and 4-Nirophenol (4-NP) contaminants as model dyes. In order to evaluate the photocatalytic activity of the prepared system various weight percent of the MOF and BaWO4 have been prepared. According to the experimental obtained results the composite photocatalyst with the weight ratio of (2:1) showed the highest photocatalytic activity to the degradation of methyl orange (MO) and 4-Nitrophenol (4-NP) water contaminants. Moreover, the ratio of (2:1) serves as the optimum amount in this system. It is noteworthy that the MOF substrate have a synergistic effect for the enhancing of photocatalytic ability. Accordingly, to further investigating the photocatalytic activity a proposed mechanism have been represented. Moreover, MOF-199-NH2/BaWO4 could be recycled several times without noticeable loss of activity.