Silicene catalyzed reduction of nitrobenzene to aniline: A mechanistic study

Morrissey, Christopher; He, Haiying

doi:10.1016/j.cplett.2018.02.027

Cited by 15 publications

(8 citation statements)

References 26 publications

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“…In the second step, with the transfer of another 2e − /2H + , IC 2 was converted to a hydroxylamine intermediate (IC 4 ). Finally, IC 4 received the last 2e − /2H + , followed by the production of aniline while eliminating a water molecule [45][46][47][48][49][50][51]. Generally, the reduction of nitrobenzene is mediated by nitroreductase, where reduced flavin mononucleotide (FMNH) is located at the active center as a coenzyme.…”

Section: Mechanism Of Single-electron Reduction Using Nitrobenzene Asmentioning

confidence: 99%

Reductive Activity and Mechanism of Hypoxia- Targeted AGT Inhibitors: An Experimental and Theoretical Investigation

Xiao

Sun

Fan

et al. 2019

IJMS

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O 6 -alkylguanine-DNA alkyltransferase (AGT) is the main cause of tumor cell resistance to DNA-alkylating agents, so it is valuable to design tumor-targeted AGT inhibitors with hypoxia activation. Based on the existing benchmark inhibitor O 6 -benzylguanine (O 6 -BG), four derivatives with hypoxia-reduced potential and their corresponding reduction products were synthesized. A reductase system consisting of glucose/glucose oxidase, xanthine/xanthine oxidase, and catalase were constructed, and the reduction products of the hypoxia-activated prodrugs under normoxic and hypoxic conditions were determined by high-performance liquid chromatography electrospray ionization tandem mass spectrometry (HPLC-ESI-MS/MS). The results showed that the reduction products produced under hypoxic conditions were significantly higher than that under normoxic condition. The amount of the reduction product yielded from ANBP (2-nitro-6-(3-amino) benzyloxypurine) under hypoxic conditions was the highest, followed by AMNBP (2-nitro-6-(3-aminomethyl)benzyloxypurine), 2-NBP (2-nitro-6-benzyloxypurine), and 3-NBG (O6-(3-nitro)benzylguanine). It should be noted that although the levels of the reduction products of 2-NBP and 3-NBG were lower than those of ANBP and AMNBP, their maximal hypoxic/normoxic ratios were higher than those of the other two prodrugs. Meanwhile, we also investigated the single electron reduction mechanism of the hypoxia-activated prodrugs using density functional theory (DFT) calculations. As a result, the reduction of the nitro group to the nitroso was proven to be a rate-limiting step. Moreover, the 2-nitro group of purine ring was more ready to be reduced than the 3-nitro group of benzyl. The energy barriers of the rate-limiting steps were 34-37 kcal/mol. The interactions between these prodrugs and nitroreductase were explored via molecular docking study, and ANBP was observed to have the highest affinity to nitroreductase, followed by AMNBP, 2-NBP, and 3-NBG. Interestingly, the theoretical results were generally in a good agreement with the experimental results. Finally, molecular docking and molecular dynamics simulations were performed to predict the AGT-inhibitory activity of the four prodrugs and their reduction products. In summary, simultaneous consideration of reduction potential and hypoxic selectivity is necessary to ensure that such prodrugs have good hypoxic tumor targeting. This study provides insights into the hypoxia-activated mechanism of nitro-substituted prodrugs as AGT inhibitors, which may contribute to reasonable design and development of novel tumor-targeted AGT inhibitors. Figure 2. Typical selected reaction monitoring (SRM) ion chromatograms of ABG, AMBG, and O 6 -BG obtained from the four prodrugs (3-NBG, 2-NBP, ANBP, and AMNBP) and the internal standard D6-O 6 -BG. The prodrugs were reduced in normoxic or hypoxic condition. (A) Control sample without 3-NBG and ANBP. (B) Reduction of 3-NBG and ANBP under normoxic conditions. (C) Reduction of 3-NBG and ANBP under hypoxic conditions. (D) Control...

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Section: Mechanism Of Single-electron Reduction Using Nitrobenzene Asmentioning

confidence: 99%

Reductive Activity and Mechanism of Hypoxia- Targeted AGT Inhibitors: An Experimental and Theoretical Investigation

Xiao

Sun

Fan

et al. 2019

IJMS

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“…On the one hand, different adsorption structures should be well considered according to the calculations in this study. On the other hand, the previous reports show that the first hydrogenation step is not the rate-determining step for the hydrogenation of nitroarenes using many catalysts. ,− A few studies reported all the elementary steps for the reduction of nitro groups from nitroaromatic reactants. , To our surprise, complete reaction pathways for the nitro group and the other bearing functional group (such as −CC and −CC) using a single substrate were not reported on metal surfaces, whereas nitrobenzene and styrene were usually adopted as models to represent the nitro and CC groups of nitroaromatics, respectively.…”

Section: Introductionmentioning

confidence: 87%

“…To our surprise, the mechanism for the selective hydrogenation of the nitro group from nitroaromatics still remains controversial, although many theoretical works have been performed. A simple reactant model such as nitrobenzene was usually adopted to represent the nitroaromatics containing reducible functional group, for example, −CC, when density functional theory (DFT) calculations were performed to unravel the reaction mechanism. − Recently, Corma and co-workers reported that the activation barrier for the activation of the −CC bond (styrene was used as a model) is lower than that for the nitro group (nitrobenzene was used as the model) using Ni(111) as the catalyst model, which is controversial to the experimental results that the selectivity is above 80% for the hydrogenation of 3-nitrostyrene to 3-vinylaniline. However, their kinetic calculations combined with experiments imply that the hydrogenation of the −CC bond is thermodynamically not favored on Ni, and the reaction rate is greatly dependent on the concentration of reactants and H 2 .…”

Section: Introductionmentioning

confidence: 99%

Mechanism of Selective Hydrogenation of 4-Nitrophenylacetylene Using Pt–Zn Intermetallic Nanoparticles: The Role of Hydrogen Coverage

et al. 2021

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Selective hydrogenation of the nitroaromatics containing other reducible functional groups is very important, but the mechanism still remains controversial. Inspired by recent work on the excellent transformation of 4nitrophenylacetylene into 4-aminophenylacetylene using the Pt−Zn intermetallic nanoparticles as catalysts (Nat. Commun. 2019, 10, 3787), theoretical investigations have been performed to unravel the mechanism. Both the positive Zn species and the moderate hydrogen coverage were found to profoundly affect the adsorption structures and the bonding strength of the functional groups, thus dramatically affecting the adsorption selectivity. In contrast to the bare surface that the hydrogenation of the −CC group competes with the −NO 2 group, the overall barrier for the hydrogenation of the −NO 2 group on the 12H−PtZn (022̅ ) model is 0.90 eV, much lower than those of the −CC group for various intermediates by at least 0.28 eV, well explaining the experimental observation of the very high selectivity and conversion. The computational results strongly support that the pre-adsorbed hydrogen greatly changes the adsorption modes of the reactants and alters the reaction mechanism and, therefore, should be carefully evaluated for the hydrogenation of nitroaromatics on metal surfaces.

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“…The reduction of nitrobenzene (PhNO 2 ) silicene to aniline (PhNH 2 ) depends on N-O adsorption and dissociation. 302 Another type of catalytic activity is predicted from the photocatalytic properties of semiconductors for the HER or ORR. 303 As mentioned, the band-gap engineering of Dirac materials (silicene and germanene) can alter the redox potentials of the materials to reach an optimum position between the conduction band minimum and valence band maximum.…”

Section: Catalysismentioning

confidence: 99%

Design, characterization, and application of elemental 2D materials for electrochemical energy storage, sensing, and catalysis

et al. 2020

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Silicene catalyzed reduction of nitrobenzene to aniline: A mechanistic study

Cited by 15 publications

References 26 publications

Reductive Activity and Mechanism of Hypoxia- Targeted AGT Inhibitors: An Experimental and Theoretical Investigation

Reductive Activity and Mechanism of Hypoxia- Targeted AGT Inhibitors: An Experimental and Theoretical Investigation

Mechanism of Selective Hydrogenation of 4-Nitrophenylacetylene Using Pt–Zn Intermetallic Nanoparticles: The Role of Hydrogen Coverage

Design, characterization, and application of elemental 2D materials for electrochemical energy storage, sensing, and catalysis

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