Efficient Catalytic Reduction of 4-Nitrophenol Using Copper(II) Complexes with N,O-Chelating Schiff Base Ligands

Abstract

The reduction of 4-nitrophenol to 4-aminophenol by sodium borohydride was used as a model to test the catalytic activity of copper(II) complexes containing N,O-chelating Schiff base ligands. In this study, a series of copper(II) complexes containing respective Schiff base ligands, N′-salicylidene-2-aminophenol (1), N′-salicylidene-2-aminothiazole (2), and N,N′-bis(salicylidene)-o-phenylenediamine (3), were synthesized and characterized by elemental analysis, Fourier transform infrared (FT-IR), and UV-Visible (UV-Vis) and electron paramagnetic resonance (EPR) spectroscopies. The results from the 4-nitrophenol reduction showed that 3 has the highest catalytic activities with 97.5% conversion, followed by 2 and 1 with 95.2% and 90.8% conversions, respectively. The optimization of the catalyst amount revealed that 1.0 mol% of the catalyst was the most optimized amount with the highest conversion compared to the other doses, 0.5 mol% and 1.5 mol%. Recyclability and reproducibility tests confirmed that all three complexes were active, efficient, and possess excellent reproducibility with consistent catalytic performances and could be used again without a major decrease in the catalytic activity.

Studying the Characteristics and Performance of a New Heterogeneous Catalyst Pre-templated Using Cu(II) Schiff Base Complex on reducing 4-nitrophenol.

“…Upon the cata'yst's addition, hydrazine hydrate and 4-NP were adsorbed on its surface and catalytic reduction was initiated immediately by transferring the hydride from the hydrazine hydrate donor to the acceptor 4-NP. Finally, with the elimination of a molecule of H2O, 4-AP departed the catalyst's surface [82]. The recyclability of the prepared catalyst was carried out five times by washing it multiple times with deionized water and reusing it for another cycle under the optimum conditions.…”

Synthesis, characterization, biological studies and DFT study of Schiff Bases and their complexes derived from aromatic diamine compounds with cobalt (II)

“…A broadband (3200-3550 cm -1 ) is present in all of the complexes, showing the presence of water molecules. Table (5) and Figures (7)(8)(9)(10) offer the ligands' UV-Visible spectral data and their complexes. At 225 nm and 246 nm, the aromatic band about the ligands L 1 and L 2 , respectively, was seen to attribute to the vanillin π π* transition's phenyl.…”

“…They are considered significant for a wide variety of progress metal catalysis responses, including epoxidation of ole-fins 5 , lactide polymerisation 6 , and the opening of the asymmetric rings of epoxides 7 . The chelating Schiff base ligands derived based on different carbonyl compounds, and diamines include a highly notable class of compounds with numerous applications in synthetic 8 , catalytic clinical 9 , analytical 10 , and biochemical 11 processes. Previous studies have shown that enhancement of the coordinating potential of diamine compounds like meta phenylene diamine happens when they are condensed with different carbonyl compounds.…”

Arc Discharge Synthesis of Chitosan‐Mediated Copper Nanoparticles for Heterogeneous Catalysis in 4‐Nitrophenol Degradation

“…[53,54] These posed to the diffusion-controlled mechanism, which is associated with the presence of Cts features, forming layers and capping the surfaces of synthesized Cu-NPs. [55,56] The limited flexibility of Cts, [52] which caps and stabilizes Cu-NPs, restricts 4-NP diffusion onto the NP surface. This constraint, caused by the Cts layer, reduces the exposed surface area of the particles available for reacting with borohydride ions.…”