Abstract:Benzimidazoles (BIs) have good and extensive biological activities in the bactericidal, anti‐inflammatory, anticancer, and antiviral fields. In addition, BIs can also be used as curing agents, metal surface treatment agents, catalysts and intermediates in organic synthesis. The preparation of BIs is an important subject of synthetic chemistry. Photocatalytic process provides a new route for the green synthesis of BIs. In this minireview, a systematic summary of the photocatalytic preparation of BIs, and the in… Show more
“…2-Substituted benz-imidazoles/-oxazoles/-thiazoles as significant types of heterocycles, have been broadly documented as structural blocks in the preparation of biological and pharmaceutical compounds (Fig. 9 ) 45 – 47 . Figure 9 Examples of biologically and pharmaceutically relevant benz-imidazoles/-oxazoles/-thiazoles.…”
Section: Resultsmentioning
confidence: 99%
“…2-Substituted benz-imidazoles/-oxazoles/-thiazoles as significant types of heterocycles, have been broadly documented as structural blocks in the preparation of biological and pharmaceutical compounds (Fig. 9) [45][46][47] .…”
Section: Synthesis and Characterization Of Co-isatin-schiff-base-mil-...mentioning
A sunlight-induced tandem air oxidation-condensation of alcohols with ortho-substituted anilines or malononitrile for the efficient synthesis of benz-imidazoles/-oxazoles/-thiazoles, or benzylidene malononitrile catalyzed by Co-isatin-Schiff-base-MIL-101(Fe) as a heterogeneous multifunctional bio-photocatalyst is reported. In these reactions, Co-isatin-Schiff-base-MIL-101(Fe) acts both as a photocatalyst, and a Lewis acid to catalyze the reaction of the in-situ formed aldehydes with o-substituted anilines or malononitrile. A significant decrease in the band gap energy and an increase in the characteristic emission of MIL-101(Fe) after functionalization with cobalt Schiff-base according to the DRS analysis and fluorescence spectrophotometry, respectively, indicate that the photocatalytic effectiveness of the catalyst is associated primarily to the synergetic influence of Fe–O cluster and Co-Schiff-base. EPR results obviously pointed out that Co-isatin-Schiff-base-MIL-101(Fe) is capable of creating 1O2 and O2⋅− as active oxygen species under visible light irradiation. Using an inexpensive catalyst, sunlight irradiation, air as a cost-effective and abundant oxidant, and a low amount of the catalyst with recoverability and durability in ethanol as a green solvent, make this methodology as an environmentally friendly process with energy-saving organic synthetic strategies. Furthermore, Co-isatin-Schiff-base-MIL-101(Fe) displays excellent photocatalytic antibacterial activity under sunlight irradiation against E. coli, S. aureus and S. pyogenes. Based on our knowledge, this is the first report of using a bio-photocatalyst for the synthesis of the target molecules.
“…2-Substituted benz-imidazoles/-oxazoles/-thiazoles as significant types of heterocycles, have been broadly documented as structural blocks in the preparation of biological and pharmaceutical compounds (Fig. 9 ) 45 – 47 . Figure 9 Examples of biologically and pharmaceutically relevant benz-imidazoles/-oxazoles/-thiazoles.…”
Section: Resultsmentioning
confidence: 99%
“…2-Substituted benz-imidazoles/-oxazoles/-thiazoles as significant types of heterocycles, have been broadly documented as structural blocks in the preparation of biological and pharmaceutical compounds (Fig. 9) [45][46][47] .…”
Section: Synthesis and Characterization Of Co-isatin-schiff-base-mil-...mentioning
A sunlight-induced tandem air oxidation-condensation of alcohols with ortho-substituted anilines or malononitrile for the efficient synthesis of benz-imidazoles/-oxazoles/-thiazoles, or benzylidene malononitrile catalyzed by Co-isatin-Schiff-base-MIL-101(Fe) as a heterogeneous multifunctional bio-photocatalyst is reported. In these reactions, Co-isatin-Schiff-base-MIL-101(Fe) acts both as a photocatalyst, and a Lewis acid to catalyze the reaction of the in-situ formed aldehydes with o-substituted anilines or malononitrile. A significant decrease in the band gap energy and an increase in the characteristic emission of MIL-101(Fe) after functionalization with cobalt Schiff-base according to the DRS analysis and fluorescence spectrophotometry, respectively, indicate that the photocatalytic effectiveness of the catalyst is associated primarily to the synergetic influence of Fe–O cluster and Co-Schiff-base. EPR results obviously pointed out that Co-isatin-Schiff-base-MIL-101(Fe) is capable of creating 1O2 and O2⋅− as active oxygen species under visible light irradiation. Using an inexpensive catalyst, sunlight irradiation, air as a cost-effective and abundant oxidant, and a low amount of the catalyst with recoverability and durability in ethanol as a green solvent, make this methodology as an environmentally friendly process with energy-saving organic synthetic strategies. Furthermore, Co-isatin-Schiff-base-MIL-101(Fe) displays excellent photocatalytic antibacterial activity under sunlight irradiation against E. coli, S. aureus and S. pyogenes. Based on our knowledge, this is the first report of using a bio-photocatalyst for the synthesis of the target molecules.
“…Importantly, the photocatalytic semiconductors simultaneously possess redox sites that can convert a substrate to the desired species in a ''one-pot'' tandem conversion process. 53 Semiconductor-type catalysts are typically used in photocatalytic reactions. The common mechanism of semiconductor-type catalysts is to generate electron-hole pairs under light irradiation.…”
The construction of carbon-nitrogen bonds is vital for producing versatile nitrogenous compounds for the chemical and pharmaceutical industries. Among developed synthetic approaches to nitrogenous chemicals, photocatalysis is particularly prominent and...
“…Benzimidazoles, as a building block of varieties of drugs, are attractive for organic chemists to design and develop new compounds for the pharmaceutical industry. , Numerous synthetic protocols have been introduced for the synthesis of 2-substituted benzimidazole derivatives using various catalytic systems. , In addition, light-driven synthesis has been developed as an alternative and sustainable method by utilizing photocatalysts, for example, photo-organocatalysts (e.g., Rose Bengal), supported catalysts (e.g., Co-loaded TiO 2 and Ti-based coordination polymers), and bimetallic systems (e.g., PANI@Au:CuO). Recently, MOFs have been used for the deposition and/or impregnation of metal NPs on their surface and/or pores, for instance, Au/MIL-101(Fe), Pt@MIL-101(Fe), and PCN-222(Pd) .…”
A photocatalytic heterojunction system was designed by hybridizing silver-deposited CuO nanoparticles (NPs) with an iron-based metal−organic framework (MOF), NH 2 -MIL-88B. The resulting system, CuO@Ag/NH 2 -MIL-88B, was thoroughly characterized, and its photoactivity was evaluated by using diffuse reflectance and photoluminescence spectroscopies. The combination of NPs and the MOF led to a red shift of the photoabsorption edges of the MOF toward the visible region. The hybrid system exhibited an energy band gap of ∼1.86 eV, in contrast to the pristine MOF with a band gap of ∼2.05 eV. The creation of a heterojunction system, known as the Z-scheme, improved charge transport and minimized charge recombination. Furthermore, the CuO@Ag/NH 2 -MIL-88B system demonstrated synergistic photoactivity in the photothermal catalytic synthesis of benzimidazoles and biaryls under visible light irradiation (LED, 100 W), aided by surface plasmonic resonance. The study revealed a high product efficiency ranging from 78 to 95% for benzimidazoles and 70−80% for biaryls, achieved within a short reaction period of 2.5−3.5 h for benzimidazoles and 6−8 h for biaryls, showcasing the photo-and thermal stability of the photocatalyst. Additionally, the photocatalyst exhibited remarkable recyclability and reusability, highlighting its potential for practical applications.
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