Nitro Reduction Reactions Research Articles

Parallel and High Throughput Reaction Monitoring with Computer Vision

AbstractWe report the development and applications of a computer vision based reaction monitoring method for parallel and high throughput experimentation (HTE). Whereas previous efforts reported methods to extract bulk kinetics of one reaction from one video, this new approach enables one video to capture bulk kinetics of multiple reactions running in parallel. Case studies, in and beyond well‐plate high throughput settings, are described. Analysis of parallel dye‐quenching hydroxylations, DMAP‐catalysed esterification, solid‐liquid sedimentation dynamics, metal catalyst degradation, and biologically‐relevant sugar‐mediated nitro reduction reactions have each provided insight into the scope and limitations of camera‐enabled high throughput kinetics as a means of widening known analytical bottlenecks in HTE for reaction discovery, mechanistic understanding, and optimisation. It is envisaged that the nature of the multi‐reaction time‐resolved datasets made available by this analytical approach will later serve a broad range of downstream efforts in machine learning approaches to exploring chemical space.

Parallel and High Throughput Reaction Monitoring with Computer Vision.

We report the development and applications of a computer vision based reaction monitoring method for parallel and high throughput experimentation (HTE). Whereas previous efforts reported methods to extract bulk kinetics of one reaction from one video, this new approach enables one video to capture bulk kinetics of multiple reactions running in parallel. Case studies, in and beyond well-plate high throughput settings, are described. Analysis of parallel dye-quenching hydroxylations, DMAP-catalysed esterification, solid-liquid sedimentation dynamics, metal catalyst degradation, and biologically-relevant sugar-mediated nitro reduction reactions have each provided insight into the scope and limitations of camera-enabled high throughput kinetics as a means of widening known analytical bottlenecks in HTE for reaction discovery, mechanistic understanding, and optimisation. It is envisaged that the nature of the multi-reaction time-resolved datasets made available by this analytical approach will later serve a broad range of downstream efforts in machine learning approaches to exploring chemical space.

Harnessing the Oxygen Vacancies in Metal Oxides for Nitroreduction

AbstractOxygen vacancies are one of the prominent types of defects in metal oxides. In addition to their role in modifying the electronic properties in solids, these sites have been shown to activate chemical bonds. As a result, the use of defect‐rich metal oxides in the organic transformations is promising. The article gives an overview of various chemical processes that are in use for the chemical reduction of aromatic nitro compounds to amines. Recently, application of oxygen vacancies in transition metal oxide for the selective reduction of aromatic nitro compounds to the corresponding amines has emerged as a new method of synthesis of amines. Oxygen vacancies in reducible oxide such as CuO have been shown to decompose hydrazine hydrate to H2 and in situ cause the reduction of nitro arenes to corresponding amines. This concept article discusses the literature pertaining to the synthesis of nitro reduction reaction, various strategies employed thus far and the place the defect‐mediated synthesis holds. The article also discusses the perspectives and challenges that remain to be addressed to gain more insights into the mechanistic understanding of the role of oxygen vacancies in nitro reduction and beyond.

One-pot Construction of Metal Nanoparticles Loaded COF Catalysts for Aqueous Hydrogenation Reactions.

The catalysis performance of metal nanoparticles (NPs) will be significantly deteriorated because of their spontaneous agglomeration during practical applications. Covalent-organic frameworks (COFs) materials with functional groups and well-defined channels benefit for the dispersion and anchor of metal ions and the confined growth of metal NPs, working as an ideal platform to compose catalytic systems. In this article, we report a one-pot strategy for the preparation of metal NPs loaded COFs without the need of post-modification. During the polymerization process, the pre-added metal ions were stabilized by the rapidly formed COF oligomers and hardly disturb the construction of COFs. After reduction, metal NPs are uniformly anchored on the COF matrix. Eventually, a wide spectrum of metal NPs, including Au, Pd, Pt, AuPd, CuPd, CuPt and CuPdPt, loaded COFs are successfully prepared. The versatility and metal ions anchoring mechanism are verified with four different COF matrixes. Taking AuPd NPs as example, the resultant AuPd NPs loaded COF materials can selectively decompose ammonium formate and produce hydrogen in-situ, exhibiting over 99 % conversion of hydrodechlorination for chlorobenzenes and nitro-reduction reaction for nitroaromatic compounds under ambient temperature in aqueous solution.

Gold nanoparticles supported on NiO and CuO: The synergistic effect toward enhanced reduction of nitroarenes and A3-coupling reaction

Bimetallic Au/NiO and Au/CuO catalysts have been developed through wet-chemical routes and the role of bimetallic effects on the reduction of nitroarenes and A3-coupling reaction have been investigated. Both bimetallic structures are ideal catalysts for aromatic nitro reduction reaction. However, using Au/NiO in A3-coupling reaction propargylamine products were selectively obtained, while diyne was obtained as the major product using Au/CuO. Both catalysts are more active than NiO and CuO in the mentioned reactions. The new bimetallic catalysts were characterized with different techniques such as XRD, Raman, SEM, HRTEM, SAED, EDX and BET nitrogen adsorption-desorption studies. These catalysts were recovered and reused in the reduction of 4-nitrophenol for about 20 times without losing catalytic activity.

Synergic degradation Chloramphenicol in photo-electrocatalytic microbial fuel cell over Ni/MXene photocathode

The abuse of Chloramphenicol (CAP) has become the increasingly serious environmental problem for its harmfulness and toxicity. A novel strategy was achieved by photocatalysis coupled with microbial fuel cell (Photo-MFC) over Ni/MXene photocathode for enhancing the degradation efficiency of (CAP). It was demonstrated that the best degradation efficiency of CAP can reach 82.62% (original concentration of 30 mg/L) after 36 h under the optimal conditions (pH = 2). Based on density functional theory (DFT) calculations and high-performance liquid chromatography-mass (HPLC-MS) spectrometry, it was speculated that the degradation mechanism of CAP in Photo-MFC over Ni/MXene photoelectrode was achieved by destroying the two asymmetric centers and nitro, including the hydrodechlorination, nitro reduction reaction, hydroxylation reaction, cleavage of CN bond and ring-opening reaction of benzene ring. Finally, the ecotoxicity evaluation of the degradation products showed that the CAP degradation in the Ni/MXene modified photo-MFC system showed a remarkable tendency to the low-toxicity level.

A mitochondria-targeting nitroreductase fluorescent probe with large Stokes shift and long-wavelength emission for imaging hypoxic status in tumor cells

Development of a mitochondria-targeting fluorescent probe with large Stokes shift and long-wavelength emission was benefit for accurate detection of hypoxic status, which was known as a major factor of the tumor physiology and influence important pathological processes. However, an efficient optical approach for simultaneously achieving such merits was still lacking. In this work, a turn-on fluorescence probe (HBT-NP) was designed to assess the hypoxic condition of tumor cells by detecting nitroreductase (NTR). Probe HBT-NP was constructed by conjugating 4-nitrobenzyl moiety as reaction site for NTR to 2-(benzo[d]thiazol-2-yl)-4-methylphenol derived fluorescent dye HBT-Py which demonstrated large Stokes shift (Δλ = 243 nm) and long wavelength emission (λem = 640 nm) due to intrinsic mechanism of ESIPT together with ICT process. Upon incubated with NTR, HBT-NP could successively undergo nitro reduction reaction and then release HBT-Py. The reaction mechanism was further confirmed by mass spectra and HPLC analysis, and the docking calculation also indicated that the binding mode and docking affinity of probe HBT-NP with NTR play an important role in catalytic reduction reaction process. As a result, HBT-NP displayed a wide linear range (0.1–1.5 μg/mL) and low detection limit (2.8 ng/mL) response to NTR, and could be used to evaluate hypoxic condition of cancer cells with precise mitochondria-targeting.

Active cobalt induced high catalytic performances of cobalt ferrite nanobrushes for the reduction of p-nitrophenol

Tremendous attention has been focused on exploring highly efficient and economical catalysts to the reduction of p-nitrophenol for the purpose of green chemistry. However, it is still a challenge to elevate the catalysts with high activity and desirable recyclability. Herein, Cobalt-Cobalt Ferrite (Co-CoFe2O4) nanobrushes have been synthesized by controlled growth-reduction process in one step, which is applied to catalyze the reduction of p-nitrophenol. In situ generated active Co(0) can induce Co-CoFe2O4 nanobrushes to achieve higher catalytic activity with a reaction rate of 0.0457 s−1 for the reduction of p-nitrophenol due to the synergetic effect between in situ generated Co(0) and its induced defects on the CoFe2O4 support. Compared with other catalysts calculated and gathered in Table S1 in Supporting Information, as-designed Co-CoFe2O4 nanobrushes can be employed as a good candidate for the nitro-reduction reaction.

Cobalt complexes of pyrrolecarboxamide ligands as catalysts in nitro reduction reactions: influence of electronic substituents on catalysis and mechanistic insights

Square-planar Co3+ complexes, displaying substrate binding abilities and facile Co3+/2+ redox potentials, function as efficient catalysts for hydrazine-mediated reduction of aromatic, heterocyclic, as well as aliphatic nitro substrates.

Conjugated polymers with defined chemical structure as model carbon catalysts for nitro reduction

Conjugated polymers with designated oxygen functionalities (–CO) are synthesized as model carbon catalysts, and a plausible catalytic mechanism involving the activation of hydrazine is proposed for nitro reduction reaction.

Self-assembled gold nanofilms as a simple, recoverable and recyclable catalyst for nitro-reduction

A facile method to prepare gold nanofilms (AuNFs), from hexaazamacrocycle (L) stabilized AuNPs, by self-assembly at liquid/liquid interfaces is developed. A vial coated with AuNFs was used as a recoverable and reusable catalytic reservoir for nitro-reduction reactions in water under ambient conditions.

Surface modification of poly(ether sulfone) membrane with a synthesized negatively charged copolymer.

In this study, we provide a new method to modify poly(ether sulfone) (PES) membrane with good biocompatibility, for which diazotized PES (PES-N2(+)) membrane is covalently coated by a negatively charged copolymer of sodium sulfonated poly(styrene-alt-maleic anhydride) (NaSPS-MA). First, aminated PES (PES-NH2) is synthesized by nitro reduction reaction of nitro-PES (PES-NO2), and then blends with pristine PES to prepare PES/PES-NH2 membrane; then the membrane is treated with NaNO2 aqueous solution at acid condition; after surface diazo reaction, surface positively charged PES/PES-N2(+) membrane is prepared. Second, poly(styrene-alt-maleic anhydride) (PS-alt-MA) is synthesized, then sulfonated and treated by sodium hydroxide solution to obtain sodium sulfonated (PS-alt-MA) (NaSPS-MA). Finally, the negatively charged NaSPS-MA copolymer is coated onto the surface positively charged PES/PES-N2(+) membrane via electrostatic interaction; after UV-cross-linking, the linkage between the PES-N2(+) and NaSPS-MA changes to a covalent bond. The surface-modified PES membrane is characterized by FT-IR spectroscopy, X-ray photoelectron spectroscopy (XPS) analyses, and surface zeta potential analyses. The modified membrane exhibits good hemocompatibility and cytocompatibility, and the improved biocompatibility might have resulted from the existence of the hydrophilic groups (sodium carboxylate (-COONa) and sodium sulfonate (-SO3Na)). Moreover, the stability of the modified membrane is also investigated. The results indicated that the modified PES membrane using negatively charged copolymers had a lot of potential in blood purification fields and bioartificial liver supports for a long time.

Highly stable covalent organic framework–Au nanoparticles hybrids for enhanced activity for nitrophenol reduction

Gold [Au(0)] nanoparticles immobilized into a stable covalent organic framework (COF) have been synthesized via the solution infiltration method. The as-synthesized Au(0)@TpPa-1 catalyst shows high recyclability and superior reactivity for nitrophenol reduction reaction than HAuCl4·3H2O.

Photoresponsive Surface Molecularly Imprinted Poly(ether sulfone) Microfibers

In the present study, photoresponsive surface molecularly imprinted poly(ether sulfone) microfibers are prepared via nitration reaction, the wet-spinning technique, surface nitro reduction reaction, and surface diazotation reaction for the selectively photoregulated uptake and release of 4-hydrobenzoic acid. The prepared molecularly imprinted microfibers show selective binding to 4-HA under irradiation at 450 nm and release under irradiation at 365 nm. The simple, convenient, effective, and productive method for the preparation of azo-containing photoresponsive material is also applied to the modification of polysulfone and poly(ether ether ketone). All three benzene-ring-containing polymers show significant photoresponsibility after the azo modification.

Quantitative structure-activity relationships for chemical reductions of organic contaminants.

Sufficient kinetic data on abiotic reduction reactions involving organic contaminants are now available that quantitative structure-activity relationships (QSARs) for these reactions can be developed. Over 50 QSARs have been reported, most in just the past few years, and they are summarized as a group here. The majority of these QSARs concern dechlorination reactions, and most of the rest concern nitro reduction reactions. Most QSARs for reduction reactions have been developed mainly as diagnostic tools for determining reduction mechanisms and pathways. So far, only a few of these QSARs are sufficiently precise in formulation, yet general in scope, that they might be useful for predicting contaminant fate. Achieving the goal of developing predictive models for the kinetics of contaminant reduction in the environment will require a delicate balance between process-level rigor and practical levels of approximation.

The effect of lindane and phenobarbital on microsomal enzyme induction in dogs and miniature swine

The enzymic activities of 9000 g supernatant fractions obtained from the livers of normal beagle dogs and miniature swine and of dogs and swine treated with lindane and phenobarbital are presented. No significant sex differences in activities were noted in control dogs. Preparations from dogs of both sexes fed lindane at 7.5 and 15.0 mg/kg exhibited a significant loss in codeine demethylase activity while nitroreductase activity was increased twofold. Phenobarbital pretreatment of dogs and swine stimulated all microsomal systems tested. Addition of lindane to the diet of these induced dogs caused a significant and rapid decline in the values after only two feedings. Enzymes induced to a greater extent in dogs by phenobarbital were inhibited to a greater extent by lindane; i.e., as a class, demethylases were affected by both lindane and phenobarbital to a greater extent than aromatic hydroxylases. In contrast, administration of lindane to phenobarbitaltreated swine caused an actual further increase in demethylase activities. A decrease in the induced state was observed in aromatic hydroxylation, azo-reduction, and nitro-reduction reactions, although the activities of these enzymes were still higher than the values from control swine.