Dataset Information

Ce@STANPs/ZrO₂ as Nanocatalyst for Multicomponent Synthesis of Isatin-Derived Imidazoles under Green Reaction Conditions.

ABSTRACT: A highly efficient and recyclable catalyst, cerium-immobilized silicotungstic acid nanoparticle-impregnated zirconia (Ce@STANPs/ZrO₂), has been synthesized. The catalytic activity of Ce@STANPs/ZrO₂ was investigated for the first time in multicomponent synthesis of isatin-based imidazoles under microwave irradiation in water. Ce@STANPs/ZrO₂ was used for C=O bond activation in overall reaction to synthesize isatin-based imidazoles. The structure of catalyst was confirmed by characterization techniques, such as Fourier transform infrared (FTIR), scanning electron microscopy (SEM)/energy dispersive X-ray, elemental mapping, transmission electron microscopy, ?-potential and diffraction light scattering, X-ray diffraction (XRD), thermogravimetric analysis, temperature-programmed desorption-NH₃, electron paramagnetic resonance (EPR), and inductively coupled plasma atomic emission spectroscopy (ICP-AES) analyses. The recovered catalyst was found to be efficient up to seventh cycle and was confirmed by FTIR, SEM, XRD, EPR, and ICP-AES analyses. The advantages of the present protocol are recyclability of catalyst, green reaction conditions, excellent yield (94%) of the products, shorter reaction time period (5-7 min), and clean reaction profile.

SUBMITTER: Khan MU

PROVIDER: S-EPMC6645424 | biostudies-literature | 2018 Aug

REPOSITORIES: biostudies-literature

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Ce@STANPs/ZrO2 as Nanocatalyst for Multicomponent Synthesis of Isatin-Derived Imidazoles under Green Reaction Conditions.

Khan Mohd Umar MU Siddiqui Zeba N ZN

ACS omega 20180831 8

A highly efficient and recyclable catalyst, cerium-immobilized silicotungstic acid nanoparticle-impregnated zirconia (Ce@STANPs/ZrO2), has been synthesized. The catalytic activity of Ce@STANPs/ZrO2 was investigated for the first time in multicomponent synthesis of isatin-based imidazoles under microwave irradiation in water. Ce@STANPs/ZrO2 was used for C=O bond activation in overall reaction to synthesize isatin-based imidazoles. The structure of catalyst was con ...[more]

PMID: 31459163

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Project description:In the present work, the activity of Ce and Er-doped ZrO2 nanopowders for sun-driven photocatalytic water oxidation has been investigated. ZrO2 powders with tunable amounts of tetragonal, monoclinic and cubic polymorphs have been synthesized by introducing Ce and Er (from 0.5 to 10 mol % on an oxide basis) through hydrothermal method. The aim of this work is to investigate the role of rare earth (RE) ions rich of electrons (Er3+) and with entirely empty levels (Ce4+) in the ZrO2 matrix for the sun-driven photocatalytic water oxidation reaction. The samples have been characterized by means of UV-Vis spectroscopy, X-Ray diffraction (XRD), N2 adsorption, X-ray photoelectron spectrophotometry (XPS) and transmission electronic microscopy (TEM) with energy dispersive spectroscopy (EDS). With respect to the bare ZrO2 mainly containing monoclinic (m-) phase, an increasing amount of rare-earth (RE) dopant was found to improve the specific BET surface area and to stabilize the tetragonal (t-) or cubic (c-) polymorphs of ZrO2 at room temperature. XRD data confirmed that dopants were mainly inserted in the t-ZrO2 phase. The photocatalytic O2 evolution from water under AM 1.5 G simulated sunlight illumination of the prepared samples have been correlated with their optical, structural and chemical properties. The effect of the dopant concentration on the chemical-physical and photocatalytic properties of the Er- and Ce-doped ZrO2 materials was elucidated. The samples with 5% of RE oxide were the most active, i.e., three times more than pure zirconia. Their superior photocatalytic activity was found to be mainly correlated to two factors: (i) an optimal surface concentration of RE ions of about 3.7%, which increased charge carriers separation in the photocatalysts surface due more superficial defects of the t-ZrO2 and a higher surface area, thus enhancing the reaction kinetics, (ii) a controlled amount of monoclinic vs. tetragonal (or cubic) polymorphs of zirconia with an optimum ratio of about 70/30 of t-ZrO2/m-ZrO2. Instead, the increased ability of the RE-doped ZrO2 to harvest visible light was found to have a secondary role on the photocatalytic activity of the Ce-doped ZrO2 material.

Dataset Information

Ce@STANPs/ZrO₂ as Nanocatalyst for Multicomponent Synthesis of Isatin-Derived Imidazoles under Green Reaction Conditions.

Publications

Ce@STANPs/ZrO<sub>2</sub> as Nanocatalyst for Multicomponent Synthesis of Isatin-Derived Imidazoles under Green Reaction Conditions.

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