Ghayah Mohammed Alsulaim

The synthesis of 2‐amino‐4 H ‐chromene‐3‐carbonitriles has gained significant research interest because of the pharmaceutical relevance of these derivatives and the growing emphasis on sustainable synthetic approaches. This review discusses recent reports on green catalytic approaches and focuses on sustainable catalytic systems, including nanocatalysts, heterogeneous catalysts, organocatalysts, photocatalysts, and other environmentally friendly catalytic methods. The review compares the performance of the catalysts, the efficiency of the reactions, the reaction mechanism, the possibility of recycling, and the green chemistry metrics, highlighting the advantages and disadvantages of each methodology. New developments, challenges, and future research avenues are also discussed, facilitating the development of more efficient, scalable, and environmentally friendly synthetic methods. This review can provide useful information for the rational design of next‐generation sustainable catalysts for the preparation of 2‐amino‐4 H ‐chromene‐3‐carbonitrile derivatives.

Nanocrystalline pure, Fe-Cu and Fe-V substituted Mn₃O₄ semiconductors were produced via a coprecipitation process as advanced magnetic compositions and efficient photocatalysts for the elimination of industrial Congo red (CR) waste. The X-ray diffraction (XRD) results confirmed that all samples have a tetragonal structure of Mn₃O₄ (hausmannite, I41/amd). The band gap energy of pure, Fe-Cu, and Fe-V co-doped Mn₃O₄ nanostructures were measured to be 2.1, 1.78, and 1.65 eV, respectively. The valence states of Cu, Fe, and V cations were confirmed by the X-ray photoelectron spectroscopy (XPS) as +2, +3, and +4, respectively. The magnetic analysis of Fe-Cu and Fe-V co-doped Mn₃O₄ powders gives room temperature hysteresis ferromagnetic curves. The obtained magnetic data demonstrated a spin-ferromagnetic order as Fe³⁺-Cu²⁺ and Fe³⁺-V⁴⁺ cations replaced Mn-sites inside Mn₃O₄ structure with measured saturation magnetization of 1.49 and 1.67 emu/g as well as coercivity of 1668 and 378 Oe, respectively. Both Fe³⁺-Cu²⁺ and Fe³⁺-V⁴⁺ mixtures, as well as the oxygen vacancies, are accountable for the ferromagnetic nature according to the bound magnetic polarons (BMPs) visualization. The Fe³⁺-Cu²⁺ substituted Mn₃O₄ semiconductor as a photocatalyst revealed a rapid solar photo-removal activity of 98% after 25 mins when applied to remove CR as industrial waste.

Gd/Fe-SnO₂ nanopowders as novel photocatalysts for the active removal of Rose Bengal dye and methyl parathion pesticide were synthesized with a low-cost coprecipitation route. The X-ray diffraction analysis of SnO₂, Sn_0.96Gd_0.02Fe_0.02O₂ and Sn_0.94Gd_0.02Fe_0.04O₂ nanopowders proved the formation of a tetragonal phase of tin oxide with average crystallite sizes in the range of 13–18 nm. The Fourier transform infrared (FTIR) spectra of all samples displayed the characteristic absorption bands of SnO₂. The nanopowder of the pure SnO₂ sample, as seen in its transmission electron microscope (TEM) image, contains spherical-like particles of variable sizes. The TEM images of the Sn_0.96Gd_0.02Fe_0.02O₂ and Sn_0.94Gd_0.02Fe_0.04O₂ powders revealed the synthesis of fine spherical nanoparticles. Based on the TEM images, the average particle size of the pure, (Gd, 2 wt% Fe) and (Gd, 4 wt% Fe) codoped SnO₂ nanopowders was estimated to be 14, 10 and 12 nm, respectively. After the addition of (Gd, 2 wt% Fe) and (Gd, 4 wt% Fe) to the SnO₂ structure, the band gap energy of SnO₂ was reduced from 3.4 eV to 2.88 and 2.82 eV, respectively. Significantly, the Sn_0.96Gd_0.02Fe_0.02O₂ nanocatalyst exhibited a high removal efficiency of 98 and 96% for Rose Bengal dye and methyl parathion pesticide after activation by sunlight for 35 and 48 min, respectively. Furthermore, this catalyst has shown perfect mineralization as well as high stability properties for the treatment of Rose Bengal dye and methyl parathion pesticide. These results suggest the suitability of the Sn_0.96Gd_0.02Fe_0.02O₂ nanocatalyst for the treatment of agriculture and industrial effluent under sunlight light energy.

Photocatalysis is considered as simple, green, and the best strategy for elimination of hazardous organic contaminants from wastewater. Herein, new broad spectrum photocatalysts based on pure and Sm-doped CuO/ZnO/CuMn₂O₄ ternary composites were simply prepared by co-precipitation approach. The X-ray diffraction results proved the formation of a composite structure. The transmission electron microscope (TEM) images displayed that most particles have a spherical shape with average mean sizes within 26–29 nm. The optical properties of both samples signified that the addition of Sm ions significantly improves the harvesting of the visible light spectrum of CuO/ZnO/CuMn₂O₄ ternary composites. The photocatalytic study confirmed that 97% of norfloxacin and 96% of methyl green pollutants were photo-degraded in the presence of the Sm-doped CuO/ZnO/CuMn₂O₄ catalyst after 50 and 40 min, respectively. The total organic carbon analysis revealed the high mineralization efficiency of the Sm-doped CuO/ZnO/CuMn₂O₄ catalyst to convert the norfloxacin and methyl green to carbon dioxide and water molecules. During three cycles, this catalyst presented a high removal efficiency for norfloxacin and methyl green contaminants. As a dielectric energy storage material, the Sm-doped CuO/ZnO/CuMn₂O₄ ternary composite has large dielectric constant values, mainly at low frequencies, with low dielectric loss compared to a pure CuO/ZnO/CuMn₂O₄ composite.