Efficient cascade C-N coupling reactions catalyzed by a recyclable MoOx/Nb2O5 nanomaterial for valuable N-heterocycles synthesis

Nb2O5/Ce1–xNbxO2−δ Nanorod Catalyst for Selective Oxidative Coupling of Aromatic Alcohols and Amines

“…19,49,50 The Nb 2 O 5 typically exhibits a pseudohexagonal phase with major XRD peaks at 2θ = 22.8, 28.6, and 36.4°. 43,51,52 The absence of these XRD peaks in NbCeNR4 and NbCeNR5 materials confirms Nb doping into the CeO 2 lattice. It should be noted that the XRD peaks are shifted to higher angles in NbCeNR materials as compared to the CeNR4 material (Figure 2b).…”

“…The Nb 3d XP spectra of all of the Nb-CeO 2 materials show two major peaks at 206.5−206.7 eV (Nb 3d 5/2 ) and 209.25−209.3 eV (Nb 3d 3/2 ), which correspond to the Nb 5+ species (Figure 5a). 43,62 This indicates the presence of Nb 2 O 5 in the Nb-CeO 2 nanorods. In addition to Nb 5+ species, the spent NbCeNR4 catalyst also contains Nb 4+ , as evidenced by two minor Nb 3d XPS peaks at 205.2 and 207.7 eV.…”

“…The geometry of these crystal facets facilitates enhanced accessibility of cerium and oxygen atoms on the surface of ceria; thus, the amount of Ce 3+/4+ species and oxygen vacancies can be optimized effectively, depending on the application of CeO 2 in heterogeneous catalysis. The rod-shaped CeO 2 is catalytically active for numerous applications, such as environmental pollution control, − biomass valorization, − CO 2 conversion, − and organic chemical transformations. ,− The oxidative coupling of alcohols and amines to produce nitrogenous chemicals is one of the important applications of shape-controlled ceria nanomaterials including nanorods in organic synthesis. − Nitrogenous chemicals, such as imines and benzimidazoles, are essential building blocks for medicinal chemistry and the pharma industry. − Using cost-effective chemicals, such as benzyl alcohol and aniline, for the synthesis of nitrogenous compounds is considered a promising strategy from an economic point of view.…”

“…On the other hand, the Nb 2 O 5 species adsorbed on the surface of CeO 2 nanorods provided strong acid sites. The presence of unsaturated, surface Nb 5+ sites enabled Nb 2 O 5 as an effective solid acid catalyst for various organic chemical transformations. ,− Thus, the Nb-CeO 2 nanorods calcined at 400 °C for 4 h showed higher catalytic activity and selectivity in the C–N coupling of benzyl alcohol with aniline and o -phenylenediamine.…”

N-doped molybdenum oxide quantum dots as fluorescent probes for the quantitative detection of copper ions in environmental samples

“…Molybdenum oxide (MoOx) is an important transition metal oxide that has garnered extensive research attention owing to its unique electrical, optical, and gas-sensitive properties. 16,17 Recently, MoOx-based nanomaterials have been increasingly employed in catalysis, 18 electronic devices, and optical sensors. 19 The composition and structure of MoOx can be manipulated by precisely controlling the synthesis conditions and processing methods to achieve the desired properties.…”