A Cu^II‐based Metal–Organic Framework as an Efficient Photocatalyst for Direct Hydroxylation of Benzene to Phenol in Aqueous Solution

Abstract

AC u II -based metal-organic framework (MOF; 1), constructed withi midazole carboxylate ligands( 5-(1 H-imidazol-1-yl)isophthalic acid) and copper(II) ions was prepared and characterizedi nd etail by XRD, Brunauer-Emmett-Teller (BET), thermogravimetric analysis( TGA), and IR methods. Its catalytic performance for the directh ydroxylation of benzene to phenol has been investigated. Abenzene conversion of 29 %a sw ell as ah igh phenol selectivity above 95 %h as been obtained at 60 8Ci nw ater.T he cycling tests showed no significant decreasea fter five runs, indicatingg ood stability and reuse properties of the Cu II -based MOF (1). The effect of addingt he hydroxyl radicals cavenger,t hiourea,a nd the ESR spectra of the catalytic system have confirmed the existence of hydroxyl radicals, which indicates the catalytic mechanism follows aF enton-type route. This economically and environmentally friendly approachw ith Cu II -basedM OFs is expected to find applications in the hydroxylation of aromatics.

Tailorable synthesis of heterogeneous enzyme–copper nanobiohybrids and their application in the selective oxidation of benzene to phenol

“…27 Recently, a few examples have been described in the literature of the application of Cu complexes in the monohydroxylation of benzene, although in most cases, low or moderate yields were obtained and total selectivity was not achieved. [26][27][28][29][30][31][32] In this work, different Cu nanobiohybrids have been synthesized for the first time via an in situ controllable Cu species and nanoparticle size in a protein host network and their properties have been demonstrated using X-ray diffraction (XRD) and transmission electron microscopy (TEM).…”

Mechanistic Insights of Chelator Complexes with Essential Transition Metals: Antioxidant/Pro-Oxidant Activity and Applications in Medicine

“…However, there is no consensus on the mechanism of the Fenton reaction with the participation of copper ions [56,60,61]. Some of the authors suggest that there are intermediate reactions with the formation of the Cu (III) ion as an intermediate product of reaction Equations ( 6)-( 8), as well as the formation of hydroxyl radicals as the final product of these reactions [56,57].…”

Recent Advances in the Heterogeneous Photocatalytic Hydroxylation of Benzene to Phenol

“…Owing to their porosity structure and high surface area, MIL-100(Fe) nanoparticles provided higher H 2 O 2 efficiency (58.5%) than MIL-68(Fe). In a later work, Cu II -based MOF was prepared for photocatalytic hydroxylation of benzene, and a Fenton oxidation mechanism was proposed [ 84 ]. In their proposed mechanism, an excited charge separation occurred in the Cu II -based MOFs under visible light, affording an electron for the reduction of Cu 2+ , which was then reduced to Cu + .…”