- A New Class of 1-Aryl-5,6-dihydropyrrolo[2,1-a]isoquinoline Derivatives as Reversers of P-Glycoprotein-Mediated Multidrug Resistance in Tumor Cells
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A number of aza-heterocyclic compounds, which share the 5,6-dihydropyrrolo[2,1-a]isoquinoline (DHPIQ) scaffold with members of the lamellarin alkaloid family, were synthesized and evaluated for their ability to reverse in vitro multidrug resistance in cancer cells through inhibition of P-glycoprotein (P-gp) and/or multidrug-resistance-associated protein 1. Most of the investigated DHPIQ compounds proved to be selective P-gp modulators, and the most potent modulator, 8,9-diethoxy-1-(3,4-diethoxyphenyl)-3-(furan-2-yl)-5,6-dihydropyrrolo[2,1-a]isoquinoline-2-carbaldehyde, attained sub-micromolar inhibitory potency (IC50: 0.19 μm). Schiff bases prepared by the condensation of some 1-aryl-DHPIQ aldehydes with p-aminophenol also proved to be of some interest, and one of them, 4-((1-(4-fluorophenyl)-5,6-dihydro-8,9-dimethoxypyrrolo[2,1-a]isoquinolin-2-yl)methyleneamino)phenol, had an IC50 value of 1.01 μm. In drug combination assays in multidrug-resistant cells, some DHPIQ compounds, at nontoxic concentrations, significantly increased the cytotoxicity of doxorubicin in a concentration-dependent manner. Studies of structure–activity relationships and investigation of the chemical stability of Schiff bases provided physicochemical information useful for molecular optimization of lamellarin-like cytotoxic drugs active toward chemoresistant tumors as well as nontoxic reversers of P-gp-mediated multidrug resistance in tumor cells.
- Nevskaya, Alisa A.,Matveeva, Maria D.,Borisova, Tatiana N.,Niso, Mauro,Colabufo, Nicola A.,Boccarelli, Angelina,Purgatorio, Rosa,de Candia, Modesto,Cellamare, Saverio,Voskressensky, Leonid G.,Altomare, Cosimo D.
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- DIRECT CONVERSION OF ANILINES INTO AMINOPHENOLS
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Hydroxylation of anilines by hydrogen peroxide in SbF5-HF yields the three possible aminophenols, the meta isomer being the major product.The reaction implies attack of protonated hydrogen peroxide H3O2(1+) on the N-protonated substrate.
- Jacquesy, Jean-Claude,Jouannetaud, Marie-Paule,Morellet, Guy,Vidal, Yves
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- Green synthesis of the Ag/HZSM-5 nanocomposite by using Euphorbia heterophylla leaf extract: A recoverable catalyst for reduction of organic dyes
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During this paper, the Ag/HZSM-5 nanocomposite has been successfully synthesized by using an aqueous extract of Euphorbia heterophylla leaves as a stabilizing and reducing agent. The green synthesized Ag/HZSM-5 nanocomposite was characterized by FT-IR (Fourier transform infrared spectroscopy), FESEM (field emission scanning electron microscopy), EDS (energy dispersion X-ray spectroscopy), UV-vis, XRD (X-ray powder diffraction) and elemental mapping. The Ag/HZSM-5 nanocomposite was found to be efficient nanocatalyst for the reduction of organic dyes such as Methylene blue (MB), Congo red (CR), Rhodamine B (RhB) and 4-nitrophenol (4-NP) in water at room temperature. The catalytic activities of the nanocatalyst in reactions were monitored by using UV-vis spectroscopy. Interestingly, the Ag/HZSM-5 catalyst can be easily recovered and reused several times without any significant loss of catalytic efficiency.
- Tajbakhsh, Mahmood,Alinezhad, Heshmatollah,Nasrollahzadeh, Mahmoud,Kamali, Taghi A.
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- Eco-Friendly In Situ Fabrication of Reduced Graphene Oxide Gold Nanocomposites for Catalysis and Dye Degradation
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Abstract: The invention represents a development of robust eco-friendly method use for water waste management and polluted water. The inadvertent role of peanut peels extract helps to simultaneously convert and form reduced graphene oxide gold nanocomposite (rGO@AuNCs) in single step. Fabricated nanocomposite was evaluated for its catalytic performance using reduction of 4-nitrophenol to 4-aminophenol as well as elimination of methylene blue (MB) and malachite green (MG) dyes from water. Graphene oxide (GO) and rGO@AuNCs, were synthesized using simplified approaches and preliminary characterization was done using UV–Vis spectrophotometer and Fourier transform infrared spectroscopy. Least concentration of rGO@AuNCs is required to eliminate MB and MG around 77 and 93%, respectively. Furthermore, surface morphology and elemental analysis of rGO@AuNCs confirm successful fabrication methods as well as X?ray diffraction pattern confirms the crystalline behavior of nanocomposite. The study illustrates an environment-friendly and cost effective in situ fabrication rGO@AuNCs from industrial agro waste for an environmental remediation.
- Patil, Pravin O.,Mahale, Sanchita S.,More, Mahesh P.,Bhandari, Pravin V.,Deshmukh, Prashant K.,Bari, Sanjay B.
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- Synthesis of a superparamagnetic ultrathin FeCO3 nanorods-enzyme bionanohybrid as a novel heterogeneous catalyst
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Herein we report a straightforward synthesis of an ultrathin protein-iron(ii) carbonate nanorods (FeCO3-NRs) heterogeneous bionanohybrid at room temperature and in aqueous media. The enzyme induced the in situ formation of well-dispersed FeCO3 NRs on a protein network. The addition of NaBH4 as a reducing agent allowed us to obtain nanorods (5 × 40 nm) with superparamagnetic properties. This bionanohybrid showed excellent catalytic results in reduction, oxidation and C-C bond reactions.
- Benavente, Rocio,Lopez-Tejedor, David,Palomo, Jose M.
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- Direct Hydrogenation of Nitroaromatics at Room Temperature Catalyzed by Magnetically Recoverable Cu@Fe2O3 Nanoparticles
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Metal embedded in metal oxide nanoparticles are active as catalyst in plethora of industrially important reactions. Herein, embedded Cu@Fe2O3 nanoparticles was synthesized via a one step hydrothermal strategy which selectively catalyzes the hydrogenation of diverse nitroaromatics in H2O at room temperature. The remarkable catalytic performance is due to the successful hybridization of metallic Cu and Fe2O3 which in turn allows easy electroflipping between various oxidation states of Cu and Fe. Azo- and azoxy-compounds are not formed during the catalyzed process. This evidently establish that the hydrogenation of nitroaromatics proceeds via direct route with >99percent selectivity to the corresponding anilines.
- Borah, Biraj Jyoti,Bharali, Pankaj
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- Green Route for the Preparation of p-Aminophenol from Nitrobenzene by Catalytic Hydrogenation in Pressurized CO2/H2O System
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The preparation of p-aminophenol from nitrobenzene by one-pot catalytic hydrogenation and in situ acid-catalyzed Bamberger rearrangement was first realized in a pressurized CO2/H2O system. By employing Pt-Sn/Al2O3 as catalyst, nitrobenzene could be converted to p-aminophenol with selectivity as high as 85% when the reaction was carried out at 140°C under 5.5 MPa CO2 and 0.2 MPa H2. This new protocol is environmentally benign because it is fully rid of the use of mineral acid by the application of self-neutralizable carbonic acid.
- Zhang, Tingting,Jiang, Jingyang,Wang, Yanhua
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- Nickel nanoparticle/carbon catalysts derived from a novel aqueous-synthesized metal-organic framework for nitroarene reduction
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Carbon-supported, non-noble metal-based catalysts derived from metal-organic frameworks (MOFs) are attractive alternatives to noble metal-based systems, but typical syntheses of the starting MOFs are not desirable from an environmental and practical perspective (e.g., they rely on non-innocuous organic solvents and long reaction times). Here, we report the preparation of a Ni-based MOF in aqueous medium, at moderate temperature (95 °C) and in a short reaction time (2 g?1 depending on the carbonization temperature applied to the MOF, as well as high Ni contents (between ～36 and 57 wt%). Notwithstanding the latter, the metal was homogeneously distributed throughout the carbon matrix in the hybrid and was quite resistant to extensive agglomeration and sintering, even at temperatures as high as 1000 °C. With increasing carbonization temperature, the Ni component was seen to go through different crystal phases, i.e., Ni3C phase → Ni hexagonal close-packed phase → Ni face-centered cubic phase. The results of the catalytic tests suggested the former and latter phases to be the most active towards the reduction of 4-NP, with catalytic activity values as high as 0.039 mol4-NP molNi?1 min?1.
- Martín-Jimeno, F. Julian,Martínez-Alonso, Amelia,Paredes, Juan I.,Suárez-García, Fabián,Tascón, Juan M. D.
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- Development of a Quasi-Steady Flow Electrochemical Paper-Based Analytical Device
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An electrochemical paper-based analytical device (ePAD) was developed for quasi-steady flow detection at microwire electrodes, for the first time. The device implements a fan shaped geometry connected to an analysis channel whereby solution is pulled from an inlet, through a channel, and into the steadily increasing capillary network of the fan. The network counteracts the decrease in solution flow rate associated with increasing viscosity within the channel, generating quasi-steady flow within the analysis channel. Microwire electrodes were embedded between two paper layers within the analysis channel, such that solution flow occurred on both sides of the wire electrodes. The quasi-steady flow ePAD increased the current by 2.5 times and 0.7 times from a saturated channel with no flow and from a single-layer paper device with flow, respectively. Amperometric detection was used for flow injection analysis (FIA) of multiple analytes at both Au and Pt microwire working electrodes, both of which provided similar sensitivity (ca. 0.2 mM-1) when normalized to the same standard. The two-layer paper devices provided a detection limit of 31 μM for p-aminophenol (PAP) using Pt electrodes and was also used to detect enzyme activity for the reaction of β-galactosidase with p-aminophenyl-galactopyranoside (PAPG). Measured enzyme kinetics provided similar Vmax (0.079 mM/min) and Km (0.36 mM) values as those found in the literature. This device shows great promise toward use in enzyme-linked immunosorbent assays or other analytical techniques where flow or washing steps are necessary. The developed sensor provides a simple and inexpensive device capable of performing multiple injection analysis with steady-flow and online detection that would normally require an external pump to perform.
- Adkins, Jaclyn A.,Noviana, Eka,Henry, Charles S.
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- Magnetic rod-based metal-organic framework metal composite as multifunctional nanostirrer with adsorptive, peroxidase-like and catalytic properties
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Although magnetic stirring is frequently used to enhance the kinetics for adsorption, chemical and biochemical reactions, the introduction of stirrers inevitably leads to the adsorption of analytes and thus interferes with the efficiency of the chemical process or reaction. In this work, magnetic Fe3O4 nanorods with tunable length-to-diameter ratio were synthesized via a hydrothermal method and used as templates for the in-situ depositing of MIL-100(Fe) and gold nanoparticles. Such nanorod-based material can not only function as an adsorbent, nanozyme, and a heterogeneous catalyst for corresponding applications but also serve as a magnetic nanostirrer to enhance kinetics. As a proof-of-concept, the capture of bacteria pathogen, mimic-peroxidase-based colorimetric detection of hydrogen peroxide, and the catalytic reduction of selected organic pollutants were conducted using the as-synthesized Fe3O4@MIL-100(Fe)-Au nanostirrer with and without magnetic field. The results show that the rates of bacteria capture, mimetic enzyme reaction and catalysis were tremendously expedited. We believe this magnetic field-assisted approach holds great promise for future applications, because, not only does it eliminate the use of external magnetic stirrers and thereby decrease the risk of foreign pollution but also, is adaptable for nanoscale reaction systems where conventional stirring is not applicable due to size limitations.
- Meteku, Benjamin Edem,Huang, Jiankun,Zeng, Jingbin,Aslam, Sobia,Zhang, Yu,Zhang, Xue,Cui, Bingwen,Wen, Cong-ying,Yan, Zifeng
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- KINETIC SUBSTITUENT AND ISOTOPE EFFECTS IN THE ACID-CATALYSED REARRANGEMENT OF N-PHENYLHYDROXYLAMINES. ARE NITRENIUM IONS INVOLVED?
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Acidity-rate profiles have been established for the rearrangement of N-phenylhydroxylamine and its derivatives in aqueous sulphuric acid and also in D2SO4-D2O.The results, particularly the change in the magnitude of the kinetic solvent isotope effect on increasing the acidity, are consistent only with a reaction mechanism involving unimolecular decomposition of the O-protonated species.N-Ethyl substitution has only a very small effect on the overall rate of reaction, whereas the rate constant was increased by ca. 100 by 4-Me substitution.The substituent effects argue against the involvement of a nitrenium ion intermediate but rather suggest that the intermediate is better represented by an imine structure with the positive charge at the 4-position in the aromatic ring.
- Kohnstam, George,Petch, W. Andrew,Williams, D. Lyn H.
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- Aniline-Hydroxylase Activity of Myoglobin by Coupling with a Membrane-Bound Electron Transport System
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Aniline-hydroxylase activity of myoglobin (Mb) can be induced by a rationally assembled semi-artificial multienzyme system of NADH - FMN - Mb on a synthetic bilayer membrane.
- Hamachi, Itaru,Fujita, Akio,Kunitake, Toyoki
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- Spectrophotometric determination of paracetamol with microwave assisted alkaline hydrolysis
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A novel and rapid spectrophotometric method for the determination of paracetamol is proposed in this paper. The proposed method is based on the microwave assisted alkaline hydrolysis of paracetamol to p-aminophenol that reacts with S2- in the presence of Fe3+ as oxidant to produce a methylene blue-like dye having an absorptivity maximum at 540nm. The experiment showed that paracetamol could be hydrolysed quantitatively to p-aminophenol in only 1.5min under radiation power 640W using a microwave in NaOH medium. The system obeys Beer's law in the range of 0-3.0×10 -4moll-1 paracetamol. The molar absorptivity and Sandell's sensitivity were found to be 3.2×103lmol-1cm -1 and 0.047μgcm-2, respectively. The relative standard deviation (n=11) was 1.7% for 8.0×10-5moll-1 paracetamol. The method has been applied successfully to analysis of paracetamol in pharmaceutical preparation.
- Xu, Chunli,Li, Baoxin
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- Fe3O4 – Glutathione stabilized Ag nanoparticles: A new magnetically separable robust and facile catalyst for aqueous phase reduction of nitroarenes
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The heterostructured Ag nanoparticles decorated Fe3O4 Glutathione (Fe3O4-Glu-Ag) nanoparticles (NPs) were synthesized by sonicating glutathione (Glu) with magnetite and further surface immobilization of silver NPs on it. The ensuing magnetic nano catalyst is well characterized by Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), high resolution transmission electron microscopy (HRTEM), powder X-ray diffraction (PXRD), thermogravimetric analysis (TGA). The prepared Fe3O4-Glu-Ag nanoparticles have proved to be an efficient and recyclable nanocatalyst with low catalyst loading for the reduction of nitroarenes and heteronitroarenes to respective amines in the presence of NaBH4 using water as a green solvent which could be easily separated at the end of a reaction using an external magnet and can be recycled up to 5 runs without any significant loss in catalytic activity. Gram scale study for the reduction of 4-NP has also being carried out successfully and it has been observed that this method can serve as an efficient protocol for reduction of nitroarenes on industrial level.
- Kumari, Mitlesh,Gupta, Ragini,Jain, Yachana
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- Highly efficient Au/TiO2 catalyst for one-pot conversion of nitrobenzene to p-aminophenol in water media
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Au/TiO2 catalyst is firstly reported to be efficient in the hydrogenation of nitrobenzene to produce p-aminophenol with a high PAP selectivity of 81% and overall yield more than 63%. The catalyst is also quite stable and can be reused for at least 4 times with only slight decrease in activity.
- Zou, Luyao,Cui, Yuanyuan,Dai, Weilin
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- A hydroquinone based palladium catalyst for room temperature nitro reduction in water
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A hydroquinone based palladium complex [Pd(H2L)(Cl)2] (1), acts as an efficient room temperature catalyst for reduction of nitroarenes in water as solvent. 1 also acts as a tandem catalyst for Suzuki-Miyaura cross coupling in ethanol followed by reduction of nitroarenes in one pot with a loading of 0.25 mol% catalyst.
- Kumar, Alok,Purkait, Kallol,Dey, Suman Kr.,Sarkar, Amrita,Mukherjee, Arindam
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- Carbonization of Co-BDC MOF results in magnetic C@Co nanoparticles that catalyze the reduction of methyl orange and 4-nitrophenol in water
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Herein we report a simple, facile and green technique for the preparation of magnetic cobalt nanoparticles (NPs) embedded on porous carbon (C@Co) nanocatalyst using MOFs template and explored for the catalytic reduction of Methyl orange (MO) and 4-Nitroph
- Ahsan, Md. Ariful,Fernandez-Delgado, Olivia,Deemer, Eva,Wang, Huiyao,El-Gendy, Ahmed A.,Curry, Michael L.,Noveron, Juan C.
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- Liquid phase hydrogenation of nitrobenzene to para-aminophenol over Pt/ZrO2 Catalyst and SO4 2-/ZrO 2-Al2O3 solid acid
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ZrO2-Al2O3 binary oxide was prepared by homogeneous coprecipitation method. SO4 2-/ZrO2 and SO4 2-/ZrO2-Al2O3 were prepared by impregnation method and were characterized by BET, XRD and TPD. Pt/ZrO2 was prepared by incipient wetness impregnation of ZrO 2 with an aqueous solution of H2PtCl6. Subsequently, hydrogenation of nitrobenzene to para-aminophenol over Pt/ZrO 2 catalyst and SO4 2-/ZrO2-Al 2O3 solid acid using water as solvent was performed. The results indicate that para-aminophenol as well as a small quantity of aniline and ortho-aminophenol are obtained without using any environmentally undesirable liquid acid. The para-aminophenol selectivity reaches to 74.9% with 44.8% of nitrobenzene conversion under the optimal reaction conditions. And the amount of Al2O3 in SO4 2-/ZrO 2-Al2O3 has great influence on the selectivity to para-aminophenol. Graphical Abstract: Hydrogenation of nitrobenzene to para-aminophenol over Pt/ZrO2 catalyst andSO4 2-/ZrO 2-Al2O3 solid acid was developed. The results indicate that para-aminophenol as well as a small quantity of aniline and ortho-aminophenol are obtained without using any environmentally undesirable liquid acid. The para-aminophenol selectivity reaches to 74.9 with 44.8% of nitrobenzene conversion under the optimal reaction conditions. And the amount of Al2O3 in SO4 2-/ZrO 2-Al2O3 has great influence on the selectivity to para-aminophenol.[Figure not available: see fulltext.]
- Liu, Pingle,Hu, Yaohua,Ni, Min,You, Kuiyi,Luo, Hean
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- Ir/C and Brφnsted acid functionalized ionic liquids an efficient catalytic system for hydrogenation of nitrobenzene to: P -aminophenol
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In this study, we found that the phenylhydroxylamine intermediate could desorb more easily from an Ir surface than from a Pt surface, which is beneficial for inhibiting the over-hydrogenation of phenylhydroxylamine to aniline. On the other hand, the Brφnsted acid functionalized ionic liquids with sulfonic acid and bisulfate anions were acidic enough to catalyze the Bamberger rearrangement to form p-aminophenol from phenylhydroxylamine. On this basis, a new catalytic system constructed by Ir/C and Brφnsted acid functionalized ionic liquid was applied, for the first time, to the one-pot hydrogenation of nitrobenzene to p-aminophenol. Our results indicate that the PAP selectivity of Ir/C and [SO3H-bmim][HSO4] Brφnsted functionalized ionic liquid was far more than that of the traditional Pt/C and sulfuric acid catalyst system. Furthermore, the dually functionalized ionic liquid ([HSO3-b-N-Bu3][HSO4]) can be used simultaneously as an acid catalyst and also as a surfactant, due to its higher lipophilicity. Therefore, our new catalytic system has unique advantages in the hydrogenation of nitrobenzene to p-aminophenol.
- Wang, Hong,Jiang, Taotao,Ma, Lei,Wang, Hanbing,Xu, Xiaoliang,Lu, Chunshan,Li, Xiaonian
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- High catalytic efficiency of nanostructured β-CoMoO4 in the reduction of the ortho-, meta- and para-nitrophenol isomers
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Nanostructured -CoMoO4 catalysts have been prepared via the thermal decomposition of an oxalate precursor. The catalyst was characterized by infrared spectroscopy (FTIR), X-ray diffraction (XRD), Brunauer-Emmett-Teller method (BET), energy dispersive X-ray spectroscopy (EDX), and transmission electron microscopy (TEM). The efficiency of these nanoparticles in the reduction of ortho- and meta-nitrophenol isomers (2-NP, 3-NP, and 4-NP) to their corresponding aminophenols was tested using UV-visible spectroscopy measurements. It was found that, with a -CoMoO4 catalyst, NaBH4 reduces 3-NP instantaneously, whilst the reduction of 2-NP and 4-NP is slower at 8 min. This difference is thought to arise from the lower acidity of 3-NP, where the negative charge of the phenolate could not be delocalized onto the oxygen atoms of the meta-nitro group.
- Al-Wadaani, Fahd,Omer, Ahmed,Abboudi, Mostafa,Hassani, Hicham Oudghiri,Rakass, Souad,Messali, Mouslim,Benaissa, Mohammed
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- Adsorption driven formate reforming into hydride and tandem hydrogenation of nitrophenol to amine over PdO: Xcatalysts
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Due to their high toxicity and non-biodegradability, efficient reduction of nitroarenes to amines is of great practical importance, yet it still remains a significant challenge. Herein, we report PdO/PdO2 nanoparticles uniformly supported on titanate nanotubes (PdOx/TiNTs) for catalyzing the tandem dehydrogenation of sodium formate (SF) and hydrogenation of p-nitrophenol (PNP) to p-aminophenol (PAmP) under mild conditions. Notably, SF adsorption is mainly driven by the hydrogen bonding interactions between the H atom in SF and surface Pd sites, which factually makes the interface of PdOx/TiNT-SF an effective platform for C-H activation. Meanwhile, it is also found that the efficiency of the hydrogenation reaction depends on the reduction rate of the nitro group to nitroso group, and the O atoms adjacent to Pd are considered as the essential sites that facilitate this process. On the basis of the above two effects, the PdOx/TiNT catalyst shows unprecedented catalytic activity (turnover frequency, TOF, is 45.6 h-1) and good selectivity (～100%) during PNP reduction at room temperature. This work deepens our understanding on tandem catalytic (de)hydrogenation systems, and will benefit the design of heterogeneous catalysts for the production of industrially important chemicals.
- Zhu, Xiaohui,Liang, Shipan,Chen, Shuang,Liu, Xiangdong,Li, Renhong
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- Hydrogenation of nitrobenzene to 4-aminophenol over supported platinum catalysts
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The conversion of nitrobenzene (NB) to p-aminophenol (PAP) takes place by way of an initial partial hydrogenation to produce phenylhydroxyl amine (PHA) which then undergoes an in situ acid-catalyzed rearrangement to PAP. This reaction is most commonly run using Pt/C catalysts in the presence of aqueous sulfuric acid and a surfactant to assist in dispersing the NB throughout the reaction medium. The yield of PAP is closely related to those reaction parameters which facilitate first the partial hydrogenation step and second the acid-promoted rearrangement before further hydrogenation to aniline can take place. The effect which a number of reaction parameters such as hydrogen pressure, reaction temperature, stirring rate, and the amounts of NB, the catalyst, and the surfactant present in the reaction mixture had on the rate and selectivity of the hydrogenation was examined. Optimization of these parameters led to the formation of PAP at a selectivity (PAP/AN) of 5.4 with a productivity of over 80,000 g PAP/g Pt/h.
- Tanielyan, Setrak K.,Nair, Jayesh J.,Marin, Norman,Alvez, Gabriela,McNair, Robert J.,Wang, Dingjun,Augustine, Robert L.
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- Kinetic rotating droplet electrochemistry: A simple and versatile method for reaction progress kinetic analysis in microliter volumes
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Here, we demonstrate a new generic, affordable, simple, versatile, sensitive, and easy-to-implement electrochemical kinetic method for monitoring, in real time, the progress of a chemical or biological reaction in a microdrop of a few tens of microliters, with a kinetic time resolution of ca. 1 s. The methodology is based on a fast injection and mixing of a reactant solution (1-10 μL) in a reaction droplet (15-50 μL) rapidly rotated over the surface of a nonmoving working electrode and on the recording of the ensuing transient faradaic current associated with the transformation of one of the components. Rapid rotation of the droplet was ensured mechanically by a rotating rod brought in contact atop the droplet. This simple setup makes it possible to mix reactants efficiently and rotate the droplet at a high spin rate, hence generating a well-defined hydrodynamic steady-state convection layer at the underlying stationary electrode. The features afforded by this new kinetic method were investigated for three different reaction schemes: (i) the chemical oxidative deprotection of a boronic ester by H2O2, (ii) a biomolecular binding recognition between a small target and an aptamer, and (iii) the inhibition of the redox-mediated catalytic cycle of horseradish peroxidase (HRP) by its substrate H2O2. For the small target/aptamer binding reaction, the kinetic and thermodynamic parameters were recovered from rational analysis of the kinetic plots, whereas for the HRP catalytic/inhibition reaction, the experimental amperometric kinetic plots were reproduced from numerical simulations. From the best fits of simulations to the experimental data, the kinetics rate constants primarily associated with the inactivation/reactivation pathways of the enzyme were retrieved. The ability to perform kinetics in microliter-size samples makes this methodology particularly attractive for reactions involving low-abundance or expensive reagents.
- Challier, Lylian,Miranda-Castro, Rebeca,Marchal, Damien,Noel, Vincent,Mavre, Francois,Limoges, Benoiit
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- Catalytic reduction of 4-nitrophenol by means of nanostructured polymeric Schiff base complexes
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Polymeric Schiff base ligands were synthesized using 2-hydroxybenzaldehyde (L2), 4-hydroxy-3-methoxybenzaldehyde (L4), and 5-aminoisophthalic acid. The nanostructured complexes were then synthesized using Ni2+, Cu2+, and Mn3+. The ligands and complexes thus synthesized were characterized using Fourier-transform infrared spectroscopy, X-ray diffraction, thermogravimetric analysis (TGA), and field-emission scanning electron microscopy. The thermal stability of the complexes was confirmed using TGA. The synthesized complexes were used as catalysts in the reduction of 4-nitrophenol (4-NP) to 4-aminophenol in an aqueous phase in the presence of sodium borohydride. In this work, the catalytic reactivity of nanostructured complexes was compared using the rate constant (k) of the reaction. The reaction time for the reduction of 4-NP was 5–14 min for different complexes. The catalytic system based on Ni2+/2-hydroxybenzaldehyde was the most active and displayed reusability in the reduction of 4-NP.
- Aghaei, Marjan,Dinari, Mohammad,Kianfar, Ali Hossein
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- Synthesis of glucose-mediated Ag-γ-Fe2O3 multifunctional nanocomposites in aqueous medium - a kinetic analysis of their catalytic activity for 4-nitrophenol reduction
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This paper reports the synthesis of γ-Fe2O3 supported Ag nanoparticles (NPs) in aqueous medium by following a green approach. The presence of Fe2O3 in the gamma phase and silver in the nanocomposite has been confirmed by Raman spectroscopy, EDAX and XPS analyses. The presence of Ag in the nanocomposite is also indicated by UV spectroscopy. In the process of in situ generation of glucose mediated Ag NPs on the γ-Fe2O3 matrix, the size of γ-Fe2O3 nanoclusters reduced from 11.6 ± 1.6 to 9 ± 1 nm as was estimated from HRTEM analysis. Glucose served as an effective stabilizer for both Ag and γ-Fe2O3 in the nanocomposite. At lower concentrations of Ag (0.15-1.2 μM) the reduction of 4-nitrophenol (4-Nip) follows pseudo-first-order kinetics and the second order rate constant for this process was found to be 5.28 × 103 dm3 mol-1 s-1. Whereas, at higher concentrations (3.2-28.9 μM), it follows zero-order kinetics and occurred with a rate constant of 1 × 10-2 mol dm-3 s-1. The amount of silver in the nanocomposite is found to influence the kinetics of the catalytic reduction in a complex scheme following the Langmuir-Hinshelwood mechanism. The recyclability of the as-synthesized nanocomposite up to 7 cycles and the catalytic effect even at a very low silver concentration (0.15 μM) associated with high surface area and superparamagnetism suggest it to be a cost effective and environmentally friendly potential catalytic system.
- Kaloti, Mandeep,Kumar, Anil,Navani, Naveen K.
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- An enzyme-copper nanoparticle hybrid catalyst prepared from disassembly of an enzyme-inorganic nanocrystal three-dimensional nanostructure
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Enzyme-copper phosphate composites with highly porous three-dimentional (3D) structures were first prepared by self-assembly of protein molecules with copper ions in phosphate buffer solution. The self-assembled enzyme-copper phosphate 3D nanostructures w
- Li, Zhixian,Ding, Yi,Wu, Xiaoling,Ge, Jun,Ouyang, Pingkai,Liu, Zheng
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- Magnetic Fe3O4/graphene oxide/copper-based nanocomposite as a reusable catalyst for the reduction of 4-nitrophenol
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In the present investigation, Fe3O4/Graphene oxide/Pr–NH2–CuII was reported as a novel magnetically recoverable nanocomposite and characterized using various analytical techniques such as FT-IR spectroscopy, field emission scanning electron microscopy (FE-SEM), energy dispersive X-ray spectroscopy (EDX), vibrating sample magnetometry (VSM), X-ray diffraction (XRD), and inductively coupled plasma (ICP). The catalytic performance of the synthesized catalyst was evaluated in the reduction of 4-nitrophenol to 4-aminophenol by an excess amount of sodium borohydride as the source of hydrogen in aqueous solution. The reaction was monitored by UV-vis spectroscopy at ambient temperature. Magnetic nature of the catalyst led to its simple recovery by a permanent magnet and excellent recyclability without appreciable loss of the catalytic activity.
- Zabihzadeh, Mehdi,Shirini, Farhad,Tajik, Hassan,Shokri, Zahra,Karami, Shiva
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- Interaction of tetrachloroethylene with rat hepatic microsomal P450-dependent monooxygenases
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1. We have studied the effects of tetrachloroethylene (PCE) on the kinetics of the P450-dependent monooxygenases in rat liver microsomes. 2. 7-Pentoxyresorufin O-depentylase (PROD) and 7-benzyloxyresorufin O-debenzylase (BROD) activities in phenobarbital (PB)-treated rat liver microsomes were substantially inhibited by PCE. The inhibition profiles were non-competitive for both enzyme activities; K(i)'s from Eadie-Hofsee plots were 0.16 and 0.29 mM for PROD and BROD respectively. In contrast, the enzyme activities in untreated, β-naphthoflavone (BNF)-, isoniazid (ISN)- and pregnenolone-16α-carbonitrile (PCN)-induced microsomes were not affected by PCE. 3. 7-Ethoxycoumarin O-deethylase (ECOD) activity in PB-induced microsomes was competitively inhibited by PCE, with a K(i) that was lower than those of other microsomes. 4. PCE inhibited 7-ethoxyresorufin O-deethylase (EROD) activities in some microsomes slightly. The K(i) for PCE was the lowest in untreated, followed by ISN-treated microsomes. 5. No effect of PCE upon aniline 4-hydroxylase (AN4H) and testosterone 6β-hydroxylase (TS6BH) activities was evident in any microsomal preparation. 6. These results indicate that PCE inhibits PB-inducible, P450-dependent monooxygenases in vitro non-competitively or competitively, and that the P450 enzymes of the P4502B subfamily may contribute to PCE toxicity.
- Hanioka,Jinno,Takahashi,Nakano,Yoda,Nishimura,Ando
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- Gold-Catalyzed Dearomative Spirocyclization of N-Aryl Alkynamides for the Synthesis of Spirolactams
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A catalytic redox-neutral method for the synthesis of spirolactams proceeding through the dearomative spirocyclization of N-aryl alkynamides is reported. In contrast to stoichiometric activating agents employed for related transformations, we show that the use of 5 mol % of Au(PPh3)Cl and AgOTf in dichloroethane at 50-80 °C leads to selective spirocyclization, furnishing the products in yields of 35-87%. The substrate scope of the reaction is good, with both electron-donating and electron-withdrawing groups being tolerated around the arene ring, as well as substitution at the amide nitrogen. The identity of the para-alkoxy group on the arene ring is key to achieving selectivity for spirocyclization over alternative mechanistic pathways. While the presence of a para-methoxy group leads to trace amounts of the desired spirolactams, the para-tert-butoxy or para-hydroxy substrate analogues furnish the spirolactams in good yield with high selectivity.
- Vacala, Taylor L.,Carlson, Paul R.,Arreola-Hester, Asa,Williams, Chloé G.,Makhoul, Evana W.,Vadola, Paul A.
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- Au(iii)-promoted polyaniline gold nanospheres with electrocatalytic recycling of self-produced reactants for signal amplification
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A novel and redox-active nanocatalyst, Au(iii)-promoted polyaniline gold nanosphere (GPANG), was designed as the nanolabel for highly efficient electrochemical immunoassay of human IgG by coupling with electrocatalytic recycling of self-produced reactants.
- Cui, Yuling,Chen, Huafeng,Tang, Dianping,Yang, Huanghao,Chen, Guonan
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p. 10307 - 10309,3
(2012)
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- Preparation of bimetallic metal-organic framework microflowers by spray method
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The NiCo-MOF microflowers are fabricated by a rapid spray method, which are assembled by 2D NiCo-MOF nanosheets with uniform crystal morphology and homogeneous dispersion of Ni and Co. Because of their large exposed active sites and nanoscale thickness, the NiCo-MOF microflowers exhibit good catalytic performance for the reduction of 4-nitrophenol.
- Zhang, Liying,Li, Linlin,Bai, Xiaojue,Xia, Mingjian,Shao, Lei,Wang, Tieqiang,Zhang, Xuemin,Li, Yunong,Qi, Xuan,Fu, Yu
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- Hydroxylation of aromatic amines with dioxygen in photooxidation sensitized by substituted phthalocyanines
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Photooxidation of aniline and its methyl and chloro derivatives with dioxygen sensitized by substituted zinc (PcZn) and palladium (PcPd) phthalocyanines in solution and on the carrier surface upon visible light irradiation affords selectively the corresponding p-aminophenols. Active and the most stable PcPd derivative adsorbed on Amberlite XAD 7HP provides conversion of 2,6-dimethylaniline with selectivity over 90% without the loss of sensitizer activity at least in 8 repeated cycles, the overall turnover number of the sensitizer being greater than 25,000.
- Fedorova, Tatyana M.,Derkacheva, Valentina M.,Shevchenko, Ekaterina N.,Luk'yanets, Evgeny A.,Bordaev, Eduard B.,Kaliya, Oleg L.
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- Transfer Hydrogenation of Nitroarenes Catalyzed by CoCu Anchored on Nitrogen-doped Porous Carbon
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The non-precious metal catalysts with high catalytic activity is extremely desirable but still full of challenges. In this paper, CoCu bimetal immobilized on nitrogen-doped porous carbon (CoCu-N-C) was prepared by an effective ligand-stabilized pyrolysis strategy. CoCu-N-C exhibited excellent catalytic efficiency for the transfer hydrogenation of nitroarenes with ammonia borane as hydrogen source, which can be ascribed to the well dispersed metal nanoparticles, the synergetic interaction of CoCu bimetal and nitrogen-doped carbon. The durability and recyclability experiments of the recycled CoCu-N-C catalyst indicated that no obvious change in catalytic performance was observed after five consecutive cycles. To gain insight into the catalytic mechanism of CoCu-N-C for the hydrogenation reaction, density functional theory calculations was also conducted. This work provides an universal approach for constructing highly efficient non-precious metal heterogeneous catalysts and which may find diverse high performance applications.
- Liu, Xiaotong,Zhang, Longkang,Wang, Junmin,Shang, Ningzhao,Gao, Shutao,Wang, Chun,Gao, Yongjun
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- Wavelength-dependent photochemistry of acetaminophen in aqueous solutions
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The influence of irradiation wavelength and intensity on photochemistry of acetaminophen (APAP) in aqueous solution was investigated by combination of steady-state and laser flash photolysis as well as HPLC and LC-MS. Steady-state irradiation at 254 nm leads to APAP disappearance with the quantum yield 0.0014 and to formation of 1-(2-amino-5-hydroxyphenyl)ethanone (P1) as a main primary photo-Fries product. In opposite the laser excitation at 266 nm leads predominantly to two-photon ionization of APAP with the quantum yield 0.013 (I = 70 mJ/cm2) and to the formation of one main product of phenoxyl radical reactions - N-(3,4-dihydroxyphenyl)acetamide (P5). Steady-state excitation at 282 nm leads to both P1 and P5 products formation indicating competition of photo-Fries and photoionization processes. The wavelength-dependent mechanism of APAP photolysis is proposed and discussed.
- Pozdnyakov, Ivan P.,Zhang, Xu,Maksimova, Tatiana A.,Yanshole, Vadim V.,Wu, Feng,Grivin, Vjacheslav P.,Plyusnin, Victor F.
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- Fabrication of thermally stable and active bimetallic Au-Ag nanoparticles stabilized on inner wall of mesoporous silica shell
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A general method has been developed for the fabrication of highly dispersed and thermally stable bimetallic Au-Ag nanoparticles (NPs) stabilized on the inner wall of a mesoporous silica shell. In our approach, gold particles were formed in the first step on carbon spheres decorated with Sn2+ cations. Upon Ag+ adsorption and reduction by l-ascorbic acid in the second step, specific nanoparticles with a gold-silver alloy core and a silver nanoshell have been formed. Important evidence of the core-shell configurations of the bimetallic Au-Ag nanoparticles were clearly characterized by UV-vis, TEM and HAADF-STEM observations combined with elemental mapping and line scans. The mesoporous silica outer shell was obtained through the hydrolysis and condensation of the precursors tetraethoxysilane (TEOS) in a basic condition and cetyltrimethylammonium bromide (CTAB) as a structure-directing agent. On this basis, the nanoreactors were fabricated after calcination, which further serves as a nanoreactor for the reduction of p-nitrophenol. Furthermore, such particles have been found to be thermally stable and their sizes remain substantially unchanged even upon calcination in air at 500 °C and a reduction treatment in H2. Potentially, the method can be developed into a general approach to synthesize other highly dispersed and thermally stable bimetallic nanoparticles stabilized on the inner wall of a mesoporous silica shell.
- Chen, Yu,Wang, Qihua,Wang, Tingmei
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- Synthesis of p-aminophenol by catalytic hydrogenation of nitrobenzene
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The present work describes the preparation of p-aminophenol via single-step catalytic hydrogenation of nitrobenzene in acid medium. A conventional method of synthesis of p-aminophenol is a two-step reaction involving iron-acid reduction of p-nitrophenol. This method causes serious effluent disposal problems due to the stoichiometric use of iron-acid, which leads to the formation of Fe-FeO sludge (?2 kg/kg of product) in the process, which cannot be recycled. The single-step hydrogenation of nitrobenzene was carried out using platinum catalyst, and the process conditions were optimized. Complete conversion of nitrobenzene was achieved with selectivity to p-aminophenol as high as 75% under the best set of conditions. Furthermore, the catalyst can be easily recovered and efficiently recycled giving the TON as high as 1.38 κ' 10.5 This paper presents studies on the effect of various process parameters such as temperature, hydrogen pressure, and substrate and acid concentration on the rate of reaction and selectivity to p-aminophenol.
- Rode,Vaidya,Chaudhari
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- Gold nanoparticles stabilized by amphiphilic hyperbranched polymers for catalytic reduction of 4-nitrophenol
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Amphiphilic hyperbranched polymers (Hx-PEI-PEG) with polyethylene glycol (PEG) chains and low-molecular-weight polyethylenimine (PEI) conjugated to commercial aliphatic hyperbranched polyesters (Boltorn Hx) were used to stabilize gold nanoparticles (AuNPs) at the interlayer between the core and the shell. It was found that low generations of Hx-PEI-PEG such as H20-PEI-PEG and H30-PEI-PEG cannot effectively stabilize AuNPs. However, H40-PEI-PEG was both the reduction agent and the stabilizer for the formation of AuNPs, which was confirmed from the solution color change and UV-vis absorption spectra. Spherical nanosized AuNPs (below 10 nm) with narrow particle size distributions were observed from the TEM images. The H40-PEI-PEG-stabilized AuNPs solution could be shelf-stored at room temperature for more than 1 month. In addition, H40-PEI-PEG-stabilized AuNPs showed high catalytic activity for the reduction of 4-nitrophenol (4-NP) to 4-aminophenol (4-AP).
- Dai, Yu,Yu, Peng,Zhang, Xiaojin,Zhuo, Renxi
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- Contrasting effect of isoflurane on drug metabolism: Decreased type I and increased type II substrate metabolism in guinea pig liver microsomes
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Inhalation anaesthetics might affect perioperative drug elimination by altering drug distribution, hepatic blood flow or drug metabolism. The in vitro effects of isoflurane on aniline hydroxylation and aminopyrine N-demethylation were investigated with guinea pig liver microsomes to assess the role of isoflurane on oxidative drug metabolism through the hepatic mixed-function oxidase system, p-Aminophenol and formaldehyde were measured spectrophotometrically as metabolic products of aniline hydroxylation and aminopyrine N-demethylation, respectively, where the reaction mixture consisted of a microsomal suspension, NADPH, aminopyrine or aniline, with or without isoflurane. The rate of cytochrome P-450 reduction by NADPH affected in the presence of isoflurane was investigated by spectrometric measurement of the CO-cytochrome P-450 complex formation at various times. Due to the addition of isoflurane, the V(max) values for aniline hydroxylation evidently increased except in high isoflurane concentration (3.33 mM) and for aminopyrine N-demethylation the value was significantly low only in the presence of a high isoflurane concentration, whereas the K(m) values significantly decreased in aniline hydroxylation and increased in aminopyrine N-demethylation, and isoflurane also accelerated the rate of cytochrome P-450 reduction by NADPH. These results reflect the inhibition of aminopyrine N-demethylation and activation of aniline hydroxylation in the presence of isoflurane as a consequence of isoflurane-accelerated cytochrome P-450 reduction by NADPH and/or drug-enzyme binding properties, and may have implications on the metabolism of perioperatively administered drugs during isoflurane anaesthesia.
- Mustafizur Rahman,Fujii, Kohyu,Kawamoto, Masashi,Yuge, Osafumi
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- Platinum N-heterocyclic carbene nanoparticles as new and effective catalysts for the selective hydrogenation of nitroaromatics
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In this communication, we report the first synthesis of Pt NPs stabilized with NHC ligands and their investigation as catalysts in the chemoselective hydrogenation of nitroarenes. The results in catalysis show that by a proper choice of the NHC stabilizer and the adjustment of the NHC/metal ratio, these NHC-capped Pt NPs exhibit high levels of activity and selectivity in the hydrogenation reactions. In particular, Pt NPs stabilized with 2 equiv. of IPr carbene (PtIPr0.2) catalyze the chemoselective reduction of a series of functionalized nitroarenes under mild conditions (1 bar H2, 30 °C). This catalyst tolerates the presence of a range of functional groups including hydroxyl, benzyloxy, carbonyl and olefinic moeities as well as halogens. Copyright
- Lara, Patricia,Suarez, Andres,Colliere, Vincent,Philippot, Karine,Chaudret, Bruno
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- Designed Meso-macroporous Silica Framework Impregnated with Copper Oxide Nanoparticles for Enhanced Catalytic Performance
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The template efficacy of solid lipid nanoparticles for generating porous silica materials with the amalgamation of Cu-functionalized cetylpyridinium chloride (CPC; as a co-emulsifier and as a metal source for generation of CuO oxide nanoparticles) has bee
- Kanwar, Rohini,Bhar, Rekha,Mehta, Surinder Kumar
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- A Simple but Efficient Catalytic Approach for the Degradation of Pollutants in Aqueous Media through Cicer arietinum Supported Ni Nanoparticles
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Plant based materials are considered to have broad applications in the remediation of toxic materials. In this report, we present an environmental friendly and economic Cicer arietinum, named as (CP) supported for the synthesis of Ni nanoparticles (NPs) designated as Ni@CP. The in situ Ni@CP NPs were obtained using aqueous medium in the presence of sodium borohydride (NaBH4) as a reducing agent. The prepared catalysts were applied for the hydrogenation/degradation of p-nitrophenol (PNP), o-nitrophenol (ONP), and 2,4-dinitrophenol (DNP), as well as congo red (CR), methyl orange (MO), methylene blue (MB) and rhodamine B (RB) dyes. The amount of total metal ions adsorbed onto the CP was evaluated by flame atomic absorption spectroscopy. The Ni@CP catalyst was characterized through PXRD, FTIR, FESEM and EDX analyses.
- Khan, Shahid Ali,Rasool, Shagufta,Rahman, Khaliq Ur,Hussain, Shah,Khan, Inamullah,Ismail, Muhammad,Farooq, Aliya,Khan, Sarzamin,Raza, Mian Ahmad,Asiri, Abdullah Muhammad,Khan, Sher Bahadar
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- Catalytically Active Bimetallic Nanoparticles Supported on Porous Carbon Capsules Derived from Metal-Organic Framework Composites
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We report a new methodology for producing monometallic or bimetallic nanoparticles confined within hollow nitrogen-doped porous carbon capsules. The capsules are derived from metal-organic framework (MOF) crystals that are coated with a shell of a secondary material comprising either a metal-tannic acid coordination polymer or a resorcinol-formaldehyde polymer. Platinum nanoparticles are optionally sandwiched between the MOF core and the shell. Pyrolysis of the MOF-shell composites produces hollow capsules of porous nitrogen-doped carbon that bear either monometallic (Pt, Co, and Ni) or alloyed (PtCo and PtNi) metal nanoparticles. The Co and Ni components of the bimetallic nanoparticles are derived from the shell surrounding the MOF crystals. The hollow capsules prevent sintering and detachment of the nanoparticles, and their porous walls allow for efficient mass transport. Alloyed PtCo nanoparticles embedded in the capsule walls are highly active, selective, and recyclable catalysts for the hydrogenation of nitroarenes to anilines.
- Yang, Hui,Bradley, Siobhan J.,Chan, Andrew,Waterhouse, Geoffrey I. N.,Nann, Thomas,Kruger, Paul E.,Telfer, Shane G.
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- High amplification rates from the association of two enzymes confined within a nanometric layer immobilized on an electrode: Modeling and illustrating example
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Electrochemical responses (e.g., chronoamperometric) obtained with an immobilized enzyme that produces an electroactive species may be used to quantitate the amount of enzyme or the concentration of its substrate. It is shown, on theoretical and experimental bases, that product-to-substrate coupling with a second enzyme co-immobilized with the first within one or within a small number of monolayers, allows high amplification rates (higher than 1000), avoids membrane transport limitations, and lends itself to precise kinetic analyses that provide guidelines for optimization of the analytical sensitivity. Very large amplification factors, as large as several thousands, can be reached experimentally, in agreement with appropriately derived theoretical predictions, thus opening the route to the rational design of high-performance substrate sensing or affinity assays applications. Copyright
- Limoges, Benoit,Marchal, Damien,Mavre, Francois,Saveant, Jean-Michel
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- Simultaneous Voltammetric Determination of Acetaminophen and Isoniazid (Hepatotoxicity-Related Drugs) Utilizing Bismuth Oxide Nanorod Modified Screen-Printed Electrochemical Sensing Platforms
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To overcome the recent outbreaks of hepatotoxicity-related drugs, a new analytical tool for the continuously determination of these drugs in human fluids is required. Electrochemical-based analytical methods offer an effective, rapid, and simple tool for on-site determination of various organic and inorganic species. However, the design of a sensitive, selective, stable, and reproducible sensor is still a major challenge. In the present manuscript, a facile, one-pot hydrothermal synthesis of bismuth oxide (Bi2O2.33) nanostructures (nanorods) was developed. These BiO nanorods were cast onto mass disposable graphite screen-printed electrodes (BiO-SPEs), allowing the ultrasensitive determination of acetaminophen (APAP) in the presence of its common interference isoniazid (INH), which are both found in drug samples. The simultaneous electroanalytical sensing using BiO-SPEs exhibited strong electrocatalytic activity toward the sensing of APAP and INH with an enhanced analytical signal (voltammetric peak) over that achievable at unmodified (bare) SPEs. The electroanalytical sensing of APAP and INH are possible with accessible linear ranges from 0.5 to 1250 μM and 5 to 1760 μM with limits of detection (3σ) of 30 nM and 1.85 μM, respectively. The stability, reproducibility, and repeatability of BiO-SPE were also investigated. The BiO-SPEs were evaluated toward the sensing of APAP and INH in human serum, urine, saliva, and tablet samples. The results presented in this paper demonstrate that BiO-SPEs sensing platforms provide a potential candidate for the accurate determination of APAP and INH within human fluids and pharmaceutical formulations.
- Mahmoud, Bahaa G.,Khairy, Mohamed,Rashwan, Farouk A.,Banks, Craig E.
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- Nickel Boride Catalyzed Reductions of Nitro Compounds and Azides: Nanocellulose-Supported Catalysts in Tandem Reactions
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Nickel boride catalyst prepared in situ from NiCl2 and sodium borohydride allowed, in the presence of an aqueous solution of TEMPO-oxidized nanocellulose (0.01 wt%), the reduction of a wide range of nitroarenes and aliphatic nitro compounds. Here we describe how the modified nanocellulose has a stabilizing effect on the catalyst that enables low loading of the nickel salt pre-catalyst. Ni-B prepared in situ from a methanolic solution was also used to develop a greener and facile reduction of organic azides, offering a substantially lowered catalyst loading with respect to reported methods in the literature. Both aromatic and aliphatic azides were reduced, and the protocol is compatible with a one-pot Boc-protection of the obtained amine yielding the corresponding carbamates. Finally, bacterial crystalline nanocellulose was chosen as a support for the Ni-B catalyst to allow an easy recovery step of the catalyst and its recyclability for new reduction cycles.
- Proietti, Giampiero,Prathap, Kaniraj Jeya,Ye, Xinchen,Olsson, Richard T.,Dinér, Peter
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supporting information
p. 133 - 146
(2021/11/04)
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- Polar hydrogen species mediated nitroarenes selective reduction to anilines over an [FeMo]Sx catalyst
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We herein present an efficient approach for the chemoselective synthesis of arylamines from nitroarenes and hydrazine over an iron-molybdenum sulfide catalyst ([FeMo]Sx). The heterogeneous hydrogen transfer reduction can be efficiently carried out at 30 °C and provides anilines with 95–99% selectivities. The in situ gas product analysis demonstrates that [FeMo]Sx can catalyze the decomposition of N2H4 to H* species, not H2. Combining with the kinetic analysis of the aniline generation rates from nitrobenzene and intermediates, the nitro group reduction to the nitroso group is confirmed to be the rate-determining step. The positive slope of Hammett's equation suggests that the critical intermediate in the rate-determining step is in the negative state, which suggests that the active H* should be in polar states (Hδ? and Hδ+). These findings will provide a novel route for the synthesis of substituted anilines and broaden the application of MoSx catalysts under mild conditions.
- Huang, Zhipeng,Li, Siqi,Liu, Huifang,Liu, Meijiang,Wang, Feng,Zhang, Chaofeng
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p. 1553 - 1560
(2022/02/03)
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- Porous polymeric ligand promoted copper-catalyzed C-N coupling of (hetero)aryl chlorides under visible-light irradiation
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A porous polymeric ligand (PPL) has been synthesized and complexed with copper to generate a heterogeneous catalyst (Cu@PPL) that has facilitated the efficient C-N coupling with various (hetero)aryl chlorides under mild conditions of visible-light irradiation at 80 °C (58 examples, up to 99% yields). This method could be applied to both aqueous ammonia and substituted amines, and is compatible to a variety of functional groups and heterocycles, as well as allows tandem C-N couplings with conjunctive dihalides. Furthermore, the heterogeneous characteristic of Cu@PPL has enabled a straightforward catalyst separation in multiple times of recycling with negligible catalytic efficiency loss by simple filtration, affording reaction mixtures containing less than 1 ppm of Cu residue. [Figure not available: see fulltext.]
- Wang, Erfei,Chen, Kaixuan,Chen, Yinan,Zhang, Jiawei,Lin, Xinrong,Chen, Mao
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- Surface Roughness Effects of Pd-loaded Magnetic Microspheres on Reduction Kinetics of Nitroaromatics
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Metal nanoparticles decoration on magnetically active semiconductor materials is a common strategy to improve the colloidal stability, catalyst harvesting, and reuse. In this study, a surfactant-free solvothermal method followed by a heat treatment to pre
- An, Seonghwi,Manivannan, Shanmugam,Viji, Mayavan,Shim, Min Suk,Hwang, Byeong Hee,Kim, Kyuwon
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supporting information
p. 894 - 899
(2021/05/06)
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- UiO-66/btb/Pd as a stable catalyst reduction of 4-nitrophenol into 4-aminophenol
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In order to synthesize highly sparse nanoparticles, UiO-66-NH2 can be utilized as an appropriate support. It has great surface area, which is functionalized by 1,3-bis(dimethylthiocarbamoyloxy)benzene compounds that can act as the powerful performers, hence, the Pd (II) is a complex without aggregate over the UiO-66-NH2 microspheres structures (UiO-66/btb/Pd). Nitro-aromatic pollution in industrial waste streams threat wellbeing of water resources. The produced UiO-66/btb/Pd nanocatalyst showed appropriate catalytic activity for reduce nitro-aromatic compounds in aqueous solution. XRD, EDS, SEM, FT-IR, and TEM were utilized for characterizing the nanostructures UiO-66/btb/Pd.
- Kiani, Zahra,Zhiani, Rahele,Khosroyar, Susan,Motavalizadehkakhky, Alireza,Hosseiny, Malihesadat
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- Aluminum Metal-Organic Framework-Ligated Single-Site Nickel(II)-Hydride for Heterogeneous Chemoselective Catalysis
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The development of chemoselective and heterogeneous earth-abundant metal catalysts is essential for environmentally friendly chemical synthesis. We report a highly efficient, chemoselective, and reusable single-site nickel(II) hydride catalyst based on robust and porous aluminum metal-organic frameworks (MOFs) (DUT-5) for hydrogenation of nitro and nitrile compounds to the corresponding amines and hydrogenolysis of aryl ethers under mild conditions. The nickel-hydride catalyst was prepared by the metalation of aluminum hydroxide secondary building units (SBUs) of DUT-5 having the formula of Al(μ2-OH)(bpdc) (bpdc = 4,4′-biphenyldicarboxylate) with NiBr2 followed by a reaction with NaEt3BH. DUT-5-NiH has a broad substrate scope with excellent functional group tolerance in the hydrogenation of aromatic and aliphatic nitro and nitrile compounds under 1 bar H2 and could be recycled and reused at least 10 times. By changing the reaction conditions of the hydrogenation of nitriles, symmetric or unsymmetric secondary amines were also afforded selectively. The experimental and computational studies suggested reversible nitrile coordination to nickel followed by 1,2-insertion of coordinated nitrile into the nickel-hydride bond occurring in the turnover-limiting step. In addition, DUT-5-NiH is also an active catalyst for chemoselective hydrogenolysis of carbon-oxygen bonds in aryl ethers to afford hydrocarbons under atmospheric hydrogen in the absence of any base, which is important for the generation of fuels from biomass. This work highlights the potential of MOF-based single-site earth-abundant metal catalysts for practical and eco-friendly production of chemical feedstocks and biofuels.
- Antil, Neha,Kumar, Ajay,Akhtar, Naved,Newar, Rajashree,Begum, Wahida,Dwivedi, Ashutosh,Manna, Kuntal
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p. 3943 - 3957
(2021/04/12)
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- Rhodium nanoparticles supported on 2-(aminomethyl)phenols-modified Fe3O4 spheres as a magnetically recoverable catalyst for reduction of nitroarenes and the degradation of dyes in water
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A magnetic nanostructured catalyst (Fe3O4@SiO2-Amp-Rh) modified with 2-(aminomethyl)phenols (Amp) was designed and prepared, which is used to catalyze the reduction of aromatic nitro compounds into corresponding amines and the degradation of dyes. The 2-aminomethylphenol motif plays a vital role in the immobilization of rhodium nanoparticles to offer extraordinary stability, which has been characterized by using various techniques, including transmission electron microscopy (TEM), thermal gravimetric analyzer (TGA), X-Ray Diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). A variety of nitroaromatic derivatives have been reduced to the corresponding anilines in water with up to yields of 99% within 1?h at room temperature. In addition, the catalyst system is effective in catalyzing the reduction of toxic pollutant 4-nitrophenol and the degradation of MO, MB and RhB dyes. Importantly, this catalyst Fe3O4@SiO2-Amp-Rh can be easily recovered by an external magnetic field because of the presence of magnetic core of Fe3O4, and the activity of Fe3O4@SiO2-Amp-Rh does not decrease significantly after 7 times’ recycling, which indicates that the catalyst performed high reactivity as well as stability. Graphical abstract: [Figure not available: see fulltext.]
- Chen, Tian,Chen, Zhangpei,Hu, Jianshe,Lv, Kexin,Reheman, Aikebaier,Wang, Gongshu
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- METHOD FOR PRODUCING AMINO AROMATIC COMPOUND
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To provide a novel method for producing an amino aromatic compound.SOLUTION: A method for producing a compound (B) having at least one amino group on an aromatic ring, includes at least a step in which a compound (A) at least having an aromatic ring and one group represented by -CR=CH2 [R is a hydrogen atom or a C1-3 alkyl group] on the aromatic ring is reacted with sodium azide in the presence of acid.SELECTED DRAWING: None
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Paragraph 0040-0043
(2021/03/03)
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- Reductive Formylation of Nitroarenes using HCOOH over Bimetallic C?N Framework Derived from the Integration of MOF and COF
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CoZn embedded C?N framework is prepared by the carbonization of CoZn containing MOF integrated with COF porous architecture in Ar atmosphere. The graphitic nature of porous carbon is confirmed from Raman analysis. The porosity and nanostructure information are retrieved from N2-sorption and transmission electron microscopic analysis, respectively. The incorporation of different metals and their oxidation states and types of nitrogen present in the C?N framework are confirmed from X-ray photoelectron spectroscopy. The basicity of the materials is determined from a CO2-temperature programmed desorption. ZnCo embedded C?N framework exhibits excellent activity in the selective reductive formylation using HCOOH. For comparison, more than 15 materials are prepared, and their activities are compared. Several control experiments are performed to establish a structure-activity relation. The recycling experiment, hot-filtration test, and poisoning experiment demonstrate the metal embedded porous C?N framework‘s recyclability and stability. A reaction mechanism for the reductive N-formylation of nitroaromatics is presented based on structure-activity relationship, control reactions, and physicochemical characterizations. The development of interesting MOF-COF-derived metal nanoclusters embedded C?N framework for selective reductive formylation of nitroaromatics using formic acid will be highly attractive to catalysis researchers and industrialists.
- Kumar Kar, Ashish,Srivastava, Rajendra
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p. 3174 - 3183
(2021/05/27)
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- TiO2/Polyethersulphone films for photocatalytic degradation of acetaminophen in aqueous solution
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In this study, TiO2-polyethersulfone films with different TiO2 loadings, prepared by the phase inversion method were tested as photocatalysts for degradation of acetaminophen in aqueous solution. The prepared films were characterized by XRD, SEM-EDX, AFM, and XPS. The successful incorporation of the titanium dioxide nanoparticles was confirmed by the XRD and SEM-EDX. SEM images revealed a much smoother surface for the pristine PES as compared to the TiO2-PES films, while EDX result confirmed the immobilization of titanium, as increasing amounts of titania were detected with increased loading of titanium dioxide. The SEM cross sectional images also show that the prepared films transformed into porous structures with tear-like pores and the porosity increased from 0.06%, for pristine PES, to 0.35% for the (14 wt%) TiO2-PES, and then dropped slightly to 0.32% in (17 wt%) TiO2-PES due to the onset of aggregation. The TiO2-PES photocatalyst film with 14 wt% content of TiO2 exhibited 51% degradation efficiency for a film surface area of 80 cm2, and a maximum efficiency of 80% at 320 cm2 film surface area. However, an increased TiO2 loading up to 17 wt% led to a decline in efficiency which is attributed to agglomeration and possible defective pore structure of the films. The reactivity of the acetaminophen molecule, modelled using the density functional theory (DFT), enabled identification of the acetamido group and the aromatic ring as the regions most prone to electrophilic and radical attack, respectively.
- Abdullah, Abdul H.,Adlan Mohd Hir, Zul,Chijioke-Okere, Maureen O.,Njoku, Paschal C.,Ogukwe, Cynthia E.,Oguzie, Emeka E.
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- Rational Approach to Plasmonic Dimers with Controlled Gap Distance, Symmetry, and Capability of Precisely Hosting Guest Molecules in Hotspot Regions
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Plasmonic dimers not only provide a unique platform for studying fundamental plasmonic behavior and effects but also are functional materials for numerous applications. The efficient creation of well-defined dimers with flexible control of structure parameters and thus tunable optical property is the prerequisite for fully exploiting the potential of this nanostructure. Herein, based on a polymer-assisted self-assembly approach in conjugation with molecular cage chemistry, a strategy was demonstrated for constructing cage-bridged plasmonic dimers with controlled sizes, compositions, shape, symmetry, and interparticle gap separation in a modular and high-yield manner. With a high degree of freedom and controllability, this strategy allows facilely accessing various symmetrical/asymmetrical dimers with sub-5 nm gap distance and tailored optical properties. Importantly, as the linkage of the two constituent elements, the molecular cages embedded in the junction endow the assembled dimers with the ability to precisely and reversibly host rich guest molecules in hotspot regions, offering great potential for creating various plasmon-mediated applications.
- Dong, Hao,Feng, Kai,He, Guokang,Li, Guangtao,Sun, Fuwei,Tian, Li,Wang, Chen,Wang, Peng,Zhao, Hongwei
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p. 8631 - 8638
(2021/06/28)
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- Regioselective Radical Arene Amination for the Concise Synthesis ofortho-Phenylenediamines
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The formation of arene C-N bonds directly from C-H bonds is of great importance and there has been rapid recent development of methods for achieving this through radical mechanisms, often involving reactiveN-centered radicals. A major challenge associated with these advances is that of regiocontrol, with mixtures of regioisomeric products obtained in most protocols, limiting broader utility. We have designed a system that utilizes attractive noncovalent interactions between an anionic substrate and an incoming radical cation in order to guide the latter to the areneorthoposition. The anionic substrate takes the form of a sulfamate-protected aniline and telescoped cleavage of the sulfamate group after amination leads directly toortho-phenylenediamines, key building blocks for a range of medicinally relevant diazoles. Our method can deliver both free amines and monoalkyl amines allowing access to unsymmetrical, selectively monoalkylated benzimidazoles and benzotriazoles. As well as providing concise access to valuableortho-phenylenediamines, this work demonstrates the potential for utilizing noncovalent interactions to control positional selectivity in radical reactions.
- Gillespie, James E.,Morrill, Charlotte,Phipps, Robert J.
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p. 9355 - 9360
(2021/07/19)
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- Synthetic method of p-hydroxybenzonitrile
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The invention discloses a synthesis method of p-hydroxybenzonitrile, which comprises the following steps: carrying out diazotization reaction on p-hydroxyaniline to form a diazo compound, and reactingthe diazo compound with cuprous chloride and sodium cyanide to obtain the p-hydroxybenzonitrile. The p-hydroxyaniline is obtained by hydrogen reduction of p-nitrosophenol, and the p-nitrosophenol isobtained by nitrosation of phenol. The reaction temperature of each step is low, the reaction conditions are mild, and the reaction power consumption is greatly reduced. The reaction can be carried out by adopting a conventional reaction kettle, the equipment requirement is low, and the investment is small. According to the method, a dehydrating agent and filler are not used, only a small amount of catalyst is used, meanwhile, the catalyst can be recycled, the solid waste amount is small, only a small amount of solid catalyst is generated, and no difficult-to-treat wastewater is generated.
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- Method for preparing p-aminophenol through nitrobenzene transfer hydrogenation
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The invention relates to a method for preparing p-aminophenol through nitrobenzene transfer hydrogenation. The method comprises the following steps: adding a hydrogen source, nitrobenzene and a catalyst into a reactor, and reacting for 2-12 hours at 60-180 DEG C under magnetic stirring to obtain a product p-aminophenol, wherein the catalyst is a supported metal catalyst and a solid acid catalyst,and the hydrogen source is an aqueous formic acid solution or isopropanol. According to the method, high-pressure H2 is prevented from being used as a raw material, so the risk of a process for preparing p-aminophenol through nitrobenzene hydrogenation is greatly reduced. The used catalyst has good catalytic performance, the highest conversion rate of nitrobenzene is 80.0%, and the highest yield of p-aminophenol is 51.3%.
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Paragraph 0028-0083
(2020/12/14)
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- A polyamine dendritic polymer-copper complex: A reusable catalyst for the additive-free amination of aryl bromides, and iodides
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A porphyrin-initiated amine-functionalized polyepichlorohydrin dendritic polymer (PPECH-Amine) was effectively synthesized, and its water-soluble copper complex (PPECH-Amine-Cu) was developed by treating it with copper acetate. PPECH-Amine and PPECH-Amine-Cu were characterised by different spectroscopic and microscopic techniques. PPECH-Amine-Cu was identified as a reusable catalyst for the amination of bromo- and iodo-benzene derivatives in aqueous media. Due to the presence of residual amino groups in the PPECH-Amine-Cu catalyst, the protocol does not need any additional base additive, as ammonia itself acts as a base and a coupling partner. Due to the good water-soluble nature of this catalyst, it can be easily separated and reused up to six reaction cycles without any loss in its activity.
- Avudaiappan,Palmurukan,Unnikrishnan,Sreekumar
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p. 1477 - 1484
(2020/02/05)
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- Synthetic method of aminophenol compounds
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The invention provides a synthesis method of aminophenol compounds. The synthesis method comprises the following steps: taking an carbon-coated nickel nano composite material containing alkaline-earthmetals as a catalyst, and catalyzing a hydrogenation reduction reaction of nitro-phenol compounds in a hydrogen atmosphere; wherein the nano composite material contains a core-shell structure with ashell layer and an inner core, the shell layer is a graphitized carbon layer containing alkaline-earth metals and oxygen, and the inner core is nickel nano particles. According to the method, the nanocomposite material is used as a catalyst; a carbon material and the nickel nano particles generate a synergistic effect and a good catalytic effect, the alkaline-earth metals of the shell layer further synergistically improve the catalytic performance of the nano composite material, and the catalyst is used for hydrogenation reduction of nitro-phenol compounds to synthesize aminophenol compounds,and has excellent activity, selectivity and safety.
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Paragraph 0130-0145; 0155-0163
(2020/08/09)
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- Ultrasound-assisted rapid reduction of nitroaromatics to anilines using gallium metal
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The reduction of nitroaromatic compounds to anilines is widely used throughout organic synthesis. Typical methods of performing this transformation utilize hydrogenation over a pyrophoric catalyst or a finely divided reducing metal, which often affords heterogeneous mixtures that are difficult to purify. Herein, we report for the first time the use of gallium metal as a reducing agent in organic synthesis. The reaction proceeds under aerobic conditions and affords homogeneous mixtures for a convenient workup. Using this method, twelve anilines were obtained in 33% to quantitative yields with short reaction times of 10-60 minutes.
- Bento, Ian,Bernaldez, Mabel,Noguchi, Ryden,Kawakami, Joel
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supporting information
p. 1404 - 1407
(2020/03/31)
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- Synthesis, characterization, and catalytic activity of half-sandwich ruthenium complexes with pyridine/phenylene bridged NHC = E (NHC = N-heterocyclic carbene, E = S, Se) ligands
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Three half-sandwichruthenium(II) complexes with pyridine/phenylene bridged NHC = E (NHC = N-heterocyclic carbene, E = S, Se) ligands [Ru(p-cymene)L](PF6)1–2 (1a–1c, L = ligand) were synthesized and characterized. All ruthenium complexes were fully characterized by 1H and 13C NMR spectra, mass spectrometry, and single-crystalX-ray diffraction methods. Moreover, the half-sandwich ruthenium complexes with NHC = E ligands showed highly catalytic activities towards to the tandem dehydrogenation of ammonia borane (AB) and hydrogenation of R–NO2 to R–NH2 at 353 K in water.
- Jia, Wei-Guo,Du, Teng-Teng,Gao, Li-Li,Du, Jun
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- A Pd confined hierarchically conjugated covalent organic polymer for hydrogenation of nitroaromatics: Catalysis, kinetics, thermodynamics and mechanism
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Herein, we propose a fast and scalable synthesis of a triazine based hierarchically conjugated covalent organic polymer under solvent and additive free conditions through a single step process. The synthesized material CCTP (Cyanuric Chloride-Thiourea-Polymer) was thoroughly characterized by various physicochemical techniques. The CCTP exhibited regular sponginess and excellent chemical as well as thermal stability. The solvent and additive free approach for CCTP synthesis provides a sustainable alternative for classical solvothermal methods. The CCTP was immobilized with Pd (0) and subsequently a heterogeneous material Pd&at;CCTP was obtained, which was used as an efficient catalyst for the hydrogenation of nitroarenes. The rate constant and Ea were measured to be 2.08 × 10-2 s-1 and 15.67 kJ mol-1 respectively and thereafter other thermodynamic parameters like ΔH, ΔS and ΔG for the hydrogenation of p-nitrophenol were also calculated. The obtained results indicate that the catalytic hydrogenation of p-nitrophenol is a non-spontaneous and endothermic process. We have also investigated the effect of surfactants (NH4OH, FA, and N2) on the reaction performance, and consequently NH4OH and FA both slow down the reaction while N2 doesn't affect the reaction medium. Further, we calculated the rate constant for the hydrogenation of 2,4-dinitrophenol and 2,4,6-trinitrophenol. An array of nitroarenes were further reduced to extend the substrate scope at RT; high TOFs were observed. Besides, Pd&at;CCTP showed excellent reusability in hydrogenation reactions without evident performance falloff.
- Awasthi, Satish Kumar,Yadav, Deepika
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p. 4295 - 4303
(2020/07/30)
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- Solvent-free synthesis of propargylamines via A3 coupling reaction and organic pollutant degradation in aqueous condition using Cu/C catalyst
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The present report focuses on the efficient and operationally simple synthesis of biomass-derived carbon as support to immobilize copper particles as a catalyst for the one-pot synthesis of propargylamines from furfural via the A3 coupling reaction. This new catalyst showed remarkable catalytic performance leading to a 97% yield within 5 h at 80 °C using 5 mg (0.0022 mmol Cu) of Cu/C catalyst under solvent-free condition. Moreover, nitro-substituted compounds such as 4-nitrophenol (4-NP) are highly toxic and not easily degradable. Hence, a quick and effective method is required to neutralize these toxic compounds. The synthesized active support Cu/C catalyst having various electron-donating groups containing small amounts of Cu plays an essential role in the catalytic reduction of 4-NP (0.1 g). Using only 3 mg (0.0013 mmol Cu) of Cu/C catalyst and NaBH4 (10 mmol), a 99% yield (100% selectivity) in the aqueous condition at 25 °C was achieved. The catalytic reduction follows the pseudo-first-order kinetics with reaction rate constant of 0.028 s?1. Moreover, results demonstrate that the Cu/C catalyst has superior catalytic activity due to the presence of electron-donating molecules such as O, S, and N atoms, which enable synergistic effect in enhancing the overall catalytic performance. Notably, the recoverability and recyclability of the synthesized catalyst were evaluated for up to four cycles, which confirmed its stability in these cycles.
- Rathod, Pramod V.,Puguan, John Marc C.,Kim, Hern
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- Atomically Dispersed Co Catalyst for Efficient Hydrodeoxygenation of Lignin-Derived Species and Hydrogenation of Nitroaromatics
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Single-atom catalysts (SACs) have attracted much attention due to their outstanding catalytic performance in heterogeneous catalysis. Here, we report a template sacrificial method to fabricate an atomically dispersed Co catalyst; three kinds of silica templates with different microstructures (MCM-41, SBA-15, and FDU-12) were employed and the effect of pore structure of the templates on the dispersity of Co was investigated. The catalysts fabricated with different templates presented different Co dispersities, leading to distinguishing catalytic performance. The optimized Co1?NC-(SBA) catalyst with atomically dispersed Co displayed outstanding catalytic activity for the hydrodeoxygenation (HDO) of lignin-derived species as well as the hydrogenation of various nitroaromatics. The reaction mechanism of the HDO of vanillin was investigated by using density functional theory calculations as well.
- Du, Congcong,Gao, Shutao,Gao, Yongjun,Huang, Jianyu,Meng, Tao,Qiao, Yuqing,Shang, Ningzhao,Shen, Tongde,Wang, Chun,Wang, Haijun,Wang, Junmin,Wang, Zhi,Wu, Qiuhua,Zhang, Longkang
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p. 8672 - 8682
(2020/09/18)
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- Palladium nanoparticles embedded in mesoporous carbons as efficient, green and reusable catalysts for mild hydrogenations of nitroarenes
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The reduction of nitroarenes is the most efficient route for the preparation of aromatic primary amines. These reductions are generally performed in the presence of heterogeneous transition metal catalysts, which are rather efficient but long and tedious to prepare. In addition, they contain very expensive metals that are in most cases difficult to reuse. Therefore, the development of efficient, easily accessible and reusable Pd catalysts obtained rapidly from safe and non-toxic starting materials was implemented in this report. Two bottom-up synthesis methods were used, the first consisted in the impregnation of a micro/mesoporous carbon support with a Pd salt solution, followed by thermal reduction (at 300, 450 or 600 °C) while the second involved a direct synthesis based on the co-assembly and pyrolysis (600 °C) of a mixture of a phenolic precursor, glyoxal, a surfactant and a Pd salt. The obtained composites possess Pd nanoparticles (NPs) of tunable sizes (ranging from 1-2 to 7.0 nm) and homogeneously distributed in the carbon framework (pores/walls). It turned out that they were successfully used for mild and environment-friendly hydrogenations of nitroarenes at room temperature under H2(1 atm) in EtOH in the presence of only 5 mequiv. of supported Pd. The determinations of the optimal characteristics of the catalysts constituted a second objective of this study. It was found that the activity of the catalysts was strongly dependent on the Pd NPs sizes,i.e., catalysts bearing small Pd NPs (1.2 nm obtained at 300 °C and 3.4 nm obtained at 450 °C) exhibited an excellent activity, while those containing larger Pd NPs (6.4 nm and 7.0 nm obtained at 600 °C, either by indirect or direct methods) were not active. Moreover, the possibility to reuse the catalysts was shown to be dependent on the surface chemistry of the Pd NPs: the smallest Pd NPs are prone to oxidation by air and their surface was gradually covered by a PdO shell decreasing their activity during reuse. A good compromise between intrinsic catalytic activity (i.e. during first use) and possibility of reuse was found in the catalyst made by impregnation followed by reduction at 450 °C since the hydrogenation could be performed in only 2 h in EtOH or even in water. The catalyst was quantitatively recovered after reaction by filtration, used at least 7 times with no loss of efficiency. Advantageously, almost Pd-free primary aromatic amines were obtained since the Pd leaching was very low (0.1% of the introduced amount). Compared to numerous reports from the literature, the catalysts described here were both easily accessible from eco-friendly precursors and very active for hydrogenations under mild and “green” reaction conditions.
- Becht, Jean-Michel,Enneiymy, Mohamed,Fioux, Philippe,Le Drian, Claude,Matei Ghimbeu, Camelia
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p. 36741 - 36750
(2020/10/19)
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- Generation and characterization of palladium nanocatalyst anchored on a novel polyazomethine support: Application in highly efficient and quick catalytic reduction of environmental contaminant nitroarenes
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Removal of toxic nitroarenes, which threaten all living organisms and environment, from wastewaters has been an important and prior issue. Therefore, the focus of the present study was to fabricate an effective, fast, reusable, and easily recoverable heterogeneous Pd nanoparticles (Pd NPs) supported on a novel polyazomethine having phenol group (Pd NPs? P(3-M-4-PAP)) for removal of several hazardous nitroarenes by catalytic reduction from water. Firstly, a novel polyazomethine featuring phenol group was prepared as a stabilizer and then, Pd NPs were anchored on it. Characterizations of the materials were performed by XRD, UV–Vis, FTIR, 1H-NMR, TGA, FE-SEM, EDS and TEM techniques. The obtained TEM analysis results showed that the size of Pd NPs was about 50 nm. Then, catalytic ability of Pd NPs?P(3-M-4-PAP) was investigated in reduction of harmful nitroarenes to useful aniline derivatives in water. Catalytic tests revealed that Pd NPs?P(3-M-4-PAP) had outstanding catalytic efficiency against reduction of different nitroarenes by giving excellent yields (up to 98%), in very short time (between 22s and 70s) with 2 mg nanocatalyst. Moreover, performed reusability test results demonstrated that the Pd NPs?P(3-M-4-PAP) could be recurrently reusable and easily recoverable.
- Y?lmaz Baran, Nuray
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- Heterogeneous photocatalysis of azides: Extending nitrene photochemistry to longer wavelengths
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The photodecomposition of azides to generate nitrenes usually requires wavelengths in the 300 nm region. In this study, we show that this reaction can be readily performed in the UVA region (368 nm) when catalyzed by Pd-decorated TiO2. In aqueous medium the reaction leads to amines, with water acting as the H source; however, in non-protic and non-nucleophilic media, such as acetonitrile, nitrenes recombine to yield azo compounds, while azirine-mediated trapping occurs in the presence of nucleophiles. The heterogeneous process facilitates catalyst separation while showing great chemoselectivity and high yields.
- Argüello, Juan E.,Lanterna, Anabel E.,Lemir, Ignacio D.,Scaiano, Juan C.
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supporting information
p. 10239 - 10242
(2020/10/02)
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- Acceptorless dehydrogenative oxidation of primary alcohols to carboxylic acids and reduction of nitroarenes via hydrogen borrowing catalyzed by a novel nanomagnetic silver catalyst
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A novel silver nano magnetic catalyst was devised for dehydrogenative oxidation of aromatic and aliphatic alcohols to the corresponding acid with water as the sole oxygen source and hydrogen gas as the only by-product. The designed catalytic system advantages from easy recovery of magnetic materials i.e. magnetic decantation, being economically viable and environmentally friendly. Furthermore, the catalytic reaction is able to reduce aryl nitro compounds in the absence of any reducing agent.
- Yazdani, Elahe,Heydari, Akbar
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supporting information
(2020/08/14)
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- Alkaline Phosphatase-Triggered in Situ Formation of Silicon-Containing Nanoparticles for a Fluorometric and Colorimetric Dual-Channel Immunoassay
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Enzyme-triggered in situ chromogenic and/or fluorogenic reactions under accessible conditions are significant for developing enzyme activity and related spectroscopic assays. Here, we describe a facile one-pot synthetic strategy to prepare silicon-containing nanoparticles with yellow-green fluorescence and orange-red color by mixing N-[3-(trimethoxysilyl)propyl]ethylenediamine and p-aminophenol (AP) in aqueous solution at a mild temperature. Encouraged by the AP-regulated simple synthetic procedure and the generation of AP from alkaline phosphatase (ALP)-catalyzed hydrolysis of 4-aminophenol phosphate (APP), a fluorometric and colorimetric dual-readout ALP activity assay can be rationally envisioned and developed by employing APP as the substrate. In the wake of the good analytical performance of such ALP activity assay and its successful combination with enzyme-linked immunosorbent assay (ELISA), corresponding fluorometric and colorimetric dual-readout ALP-based ELISA has been constructed for highly sensitive and quantitative determination of human prostate-specific antigen (PSA), the key biomarker of prostate cancer in human serum. The convincing performance in evaluating the PSA level in serologic tests unambiguously reveals the great potential of our proposed fluorometric and colorimetric dual-channel immunoassay in early clinical diagnosis by monitoring disease biomarkers.
- Chen, Chuanxia,Jiang, Yuanyuan,Lu, Yizhong,Ni, Pengjuan,Sun, Jian,Wang, Bo,Yang, Fan,Zhang, Chenghui,Zhao, Dan
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p. 4639 - 4646
(2020/04/02)
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- Bimetallic photoredox catalysis: Visible light-promoted aerobic hydroxylation of arylboronic acids with a dirhodium(ii) catalyst
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We report the use of a rhodium(II) dimer in visible light photoredox catalysis for the aerobic oxidation of arylboronic acids to phenols under mild conditions. Spectroscopic and computational studies indicate that the catalyst Rh2(bpy)2(OAc)4 (1) undergoes metal-metal to ligand charge transfer upon visible light irradiation, which is responsible for catalytic activity. Further reactivity studies demonstrate that 1 is a general photoredox catalyst for diverse oxidation reactions.
- Campbell, Michael G.,Chuang, Gary Jing,Liu, Ming-Lun,Miura-Stempel, Emily,Tu, Jing-Wen,Yang, Hsiang-Ming
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p. 2040 - 2047
(2020/03/13)
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- Coupled heterogeneous photocatalysis using a P-TiO2-αFe2O3 catalyst and K2S2O8 for the efficient degradation of a sulfonamide mixture
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Phosphorous-doped Ti-Fe mixed oxide (P-TiO2-αFe2O3) catalysts were prepared by the microwave-assisted sol-gel route and characterized using XRD, SEM, N2 physisorption, UV–vis diffuse reflectance, FTIR, and XPS. P-TiO2-αFe2O3 was evaluated during the degradation of a sulfonamide mixture (5 mg/L, each) under visible light. The photocatalytic process was optimized with a face-centered central composite design. Under optimal conditions (0.5 wt% of αFe2O3, pH 10, and 0.75 g/L of catalyst loading), the sulfate radical advanced oxidation process was carried out using 5 mM K2S2O8 (PS). P doping shifted the light absorption of P-TiO2-αFe2O3 in the visible light range owing to substitutional doping, while the coupling of P-TiO2 with α-Fe2O3 enhanced the absorption in the visible range, which resulted in an increase in the lifetime of the charge carriers and in a superior photoactivity of the P-TiO2-αFe2O3 catalyst in comparison to that of TiO2. The mineralization yield of the sulfonamides (SNs) mixture was enhanced in the presence of an electron acceptor (SO4 ? [rad]), allowing nearly 69 % within 300 min with the P-TiO2-αFe2O3/PS system, while P-TiO2-αFe2O3 and K2S2O8 oxidation achieved only 27 % and 21 %, respectively. The biodegradability index was 0.48 using the P-TiO2-αFe2O3/PS system, indicating a less toxic effluent than the original compounds. Recycling tests demonstrated that P-TiO2-αFe2O3 exhibits good stability in activating PS for SNs degradation during three cycles. Two main intermediates (pyrimidine and hydroquinone) and their hydroxylated re-arrangements were detected during the degradation of the SNs by the coupled process. Oxalic, oxamic, sulfonic, and acetic acids were also identified as by-products from the degradation of the SNs.
- Guzmán-Mar, Jorge L.,Hernández-Ramírez, Aracely,Hinojosa-Reyes, Laura,Mendiola-Alvarez, Sandra Y.,Palomino-Cabello, Carlos,Turnes-Palomino, Gemma
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- Method for preparing aromatic amine by one-pot method of aromatic ketone
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The invention discloses a method for preparing aromatic amine by an aromatic ketone one-pot method. The method comprises the following steps: uniformly mixing a protonic acid catalyst with aromatic ketone, wherein the molar ratio of the protonic acid catalyst to aromatic ketone is (0.5-8):1; adding hydroxylamine hydrochloride into the obtained mixed solution, wherein the molar ratio of hydroxylamine hydrochloride to a carbonyl group of aromatic ketone is (1-2):1; raising the temperature under a stirring condition to 60-140 DEG C for a reaction; adding hydrochloric acid after finish of the reaction to hydrolyze a generated amide group into an amino; and performing cooling and crystallization to obtain aromatic amine. Polyphosphoric acid, concentrated sulfuric acid and methanesulfonic acid are adopted for catalysis to prepare aromatic amine in one step. Compared with a conventional method, the method provided by the invention has the advantages that reaction steps are reduced, the technological process is greatly simplified, the period is shortened, the cost is lowered, and the efficiency and the productivity are remarkably improved.
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Paragraph 0044-0045; 0086-0087
(2020/06/02)
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- Visible-light-promoted aerobic oxidative hydroxylation of arylboronic acids in water by hydrophilic organic semiconductor
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A green and sustainable catalytic system was developed based on perylenediimide (PDI) organic semiconductor for the aerobic oxidative hydroxylation of arylboronic acids in aqueous solution with visible light. By using PDI-SN, a hydrophilic organic semiconductor, which can activate oxygen to produce superoxide radicals in aqueous solution, this reaction proceeds under ambient conditions: water as the solvent and air as the oxidant, giving various phenols as products with high yields. In contrast to methods using organic solvents, this novel process has the potential of green industrial application.
- Yu, Kunyi,Zhang, Hanjie,Sheng, Yuqiang,Zhu, Yongfa
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supporting information
(2020/06/23)
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- Photoluminescence as a valuable tool in the optical characterization of acetaminophen and the monitoring of its photodegradation reactions
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In this work, new evidence for the photodegradation reactions of acetaminophen (AC) is reported by photoluminescence (PL), Raman scattering and FTIR spectroscopy. Under excitation wavelength of 320 nm, AC shows a PL band in the spectral range of 340–550 nm, whose intensity decreases by exposure to UV light. The chemical interaction of AC with the NaOH solutions, having the concentration ranging between 0.001 and 0.3 M, induces a gradual enhancement of the photoluminescence excitation (PLE) and PL spectra, when the exposure time of samples at the UV light increases until 140 min, as a result of the formation of p-aminophenol and sodium acetate. This behavior is not influenced by the excipients or other active compounds in pharmaceutical products as demonstrated by PLE and PL studies. Experimental arguments for the obtaining of p-aminophenol and sodium acetate, when AC has interacted with NaOH, are shown by Raman scattering and FTIR spectroscopy.
- Baibarac, Mihaela,Daescu, Monica,Ion, Alina C.,Matea, Adelina,Negrila, Catalin,Serbschi, Constantin
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- Cu(I)/sucrose-catalyzed hydroxylation of arenes in water: The dual role of sucrose
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A protocol for the hydroxylation of aryl halides catalyzed by copper(I) and sucrose in neat water has been developed. The dual role of sucrose, the reaction pathway, and the high selectivity for hydroxylation were investigated using a combination of experimental and theoretical techniques. This journal is
- Murata, Shigeo,Takagi, Mio,Takita, Ryo,Watanabe, Ayako,Watanabe, Kohei
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supporting information
p. 7827 - 7831
(2020/11/02)
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- Silver-Catalyzed para-Selective Amination and Aminative Dearomatization of Phenols with Azodicarboxylates in Water
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An efficient silver-catalyzed para-selective amination and aminative dearomatization of phenols with azodicarboxylates was developed. It afforded the para-aminophenols or amino cyclohexadieneones from free phenols depending on whether it has a para-substituent. The reaction proceeded smoothly in water under simple and mild conditions, giving the highly selective products in good yields within a short reaction time. It also showed broad substrate scope and good functional group compatibility.
- Li, Dong,Liu, Jixiang,Wang, Xia,Zhang, Qian,Zhao, Ruinan,Zhou, Zhong
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supporting information
p. 8144 - 8149
(2020/11/02)
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- Trinuclear Mn2+/Zn2+based microporous coordination polymers as efficient catalysts foripso-hydroxylation of boronic acids
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Two microporous coordination polymers based on hourglass trinuclear building units, [Mn3(bpdc)3(bpy)]·2DMF and [Zn3(bpdc)3(bpy)]·2DMF·4H2O (bpdc = 4,4′-biphenyl dicarboxylic acid, bpy = 4,4′-bipyridine), have been synthesized under solvothermal conditions employing DMF as the solvent. Each structure consists of two crystallographically distinct M2+(M1 and M2) centers that are connectedviacarboxylate bridges from six bpdc ligands, generating a trinuclear metal cluster, [M3(bpdc)3(bpy)]. Cluster representation of the structure resulted in an interpenetrated net of rarehextopological type. Catalytic activities of the CPs have been assessed for the oxidative hydroxylation of phenylboronic acids (PBAs) using aqueous hydrogen peroxide (H2O2). Various substituted aryl/hetero-arylboronic acids RB(OH)2[R = phenyl, 2,4-difluorophenyl, 4-aminophenyl, 2-thiopheneetc.] underwentipso-hydroxylation smoothly at room temperature to generate the corresponding phenols in excellent yields. The main advantages of this protocol are the aqueous medium reaction, heterogeneous catalytic system, and short reaction time with excellent yield.
- Bora, Sanchay J.,Dutta, Anurag,Goswami, Shyam,Guha, Ankur K.,Paul, Rima,Thakur, Ashim J.
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p. 5454 - 5462
(2020/05/16)
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- Aerobic photooxidative hydroxylation of boronic acids catalyzed by anthraquinone-containing polymeric photosensitizer
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We report herein the synthesis of a polymeric photosensitizer and its application in aerobic photooxidative hydroxylation of boronic acids. The polymeric photosensitizer was synthesized by the condensation of anthraquinone-2-carbonyl chloride (AQ-2-COCl) with poly (2-hydroxyethyl methacrylate) (PHEMA). The photo-oxidative hydroxylation of boronic acids using anthraquinone-containing-poly (2-hydroxyethyl methacrylate) (AQ-PHEMA) was then explored and shown to exhibit high efficiency and broad scope. Moreover, AQ-PHEMA could be easily recovered and reused for more than 20 times without significant loss of the catalytic activity.
- Chen, Yang,Ding, Aishun,Hu, Jianhua
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p. 7927 - 7932
(2020/03/11)
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- Silicon-grafted Ag/AgX/rGO nanomaterials (X = Cl or Br) as dip-photocatalysts for highly efficient p-nitrophenol reduction and paracetamol production
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In this work, plasmonic Ag/AgX/rGO (X?=?Cl or Br) nano-photocatalysts were grafted with silicon by adding trimethylsilyl chloride as silicon precursor. The synthesized Ag/AgX/rGO-Si hybrids showed a large improvement of photocatalytic activity towards the synthesis of p-aminophenol (PAP) as well as paracetamol (acetaminophen; APAP) through the photoreduction of p-nitrophenol (PNP). The prepared catalysts Ag/AgX/rGO were characterized using SEM, XRD, FTIR and the reduction reaction of p-nitrophenol was monitored by UV–Vis measurements, GC/MS and 1HNMR data. From the results, it was demonstrated that the rate order of reduction process of the PNP to PAP and to APAP under visible light irradiation of the samples was as follows; Ag/AgBr/rGO-Si?>?Ag/AgCl/rGO-Si?>?Ag/AgBr/rGO?>?Ag/AgCl/rGO. The reaction mechanism had been postulated that was supported with the spectroscopic data. In addition, the catalysts were recovered from the reaction medium and re-used in three cycles that indicated the reusability and stability of the catalysts. This study was featured by the following; i) fast reaction, ii) the reduction of p-nitrophenol to paracetamol was performed in a facile one-pot reaction compared to previous approaches that tends to reduce the production cost, and iii) investigations on the catalytic properties of Ag/AgX/rGO in organic transformations open the door to find a benefice of these catalysts in other organic reactions and in the development in the synthesis of pharmaceutical products.
- Attia, Yasser A.,Mohamed, Yasser M.A.
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- Copper(ii)-catalyzed c-n coupling of aryl halides and n-nucleophiles promoted by quebrachitol or diethylene glycol
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Herein, we report the natural ligand quebrachitol (QCT) as a promoter for a Cu(II) catalyst, which is highly effective for N-Arylation of various amines and related aryl halides. A series of diarylamine derivatives were obtained in high yields by using diethylene glycol (DEG) as both ligand and solvent. The C-N coupling reactions proceed under mild conditions and exhibit good functional group tolerance.
- Chen, Guoliang,Chen, Yuanguang,Du, Fangyu,Fu, Yang,Wu, Ying,Zhou, Qifan
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supporting information
p. 2161 - 2168
(2019/11/25)
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- Atomically precise Ag nanoclusters intercalated in zirconium pyrophosphate for efficient hydrogenation of nitroaromatics
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Designing and fabricating catalysts with highly dispersed metal nanoclusters (NCs) is very crucial for achieving high activity and selectivity. In this work, all-alkynyl-protected [Ag74(C≡CPh)44](NO3)2 cluster (
- Gong, Honghui,Lin, Lina,Zhao, Xiuge,Li, Huan,Li, Difan,Xu, Zichen,Chen, Manyu,Huang, Rong,Hou, Zhenshan
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- Well-Defined Metal Nanoparticles@Covalent Organic Framework Yolk–Shell Nanocages by ZIF-8 Template as Catalytic Nanoreactors
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Yolk–shell nanoreactors have received considerable interest for use in catalysis. However, the controlled synthesis of continuous crystalline shells without imperfections or cracks remains challenging. Here, a strategy for the synthesis of yolk–shell meta
- Cui, Kaixun,Zhong, Wanfu,Li, Lingyun,Zhuang, Zanyong,Li, Liuyi,Bi, Jinhong,Yu, Yan
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- Synthesis of a highly active amino-functionalized Fe3O4@SiO2/APTS/Ru magnetic nanocomposite catalyst for hydrogenation reactions
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An amino-functionalized silica-coated Fe3O4 nanocomposite (Fe3O4@SiO2/APTS) was synthesized. The Fe3O4@SiO2 microspheres possessed a well-defined core–shell structure,
- Liu, Yue,Lv, Mingxin,Li, Lu,Yu, Hailong,Wu, Qiong,Pang, Jinhui,Liu, Yuxiang,Xie, Congxia,Yu, Shitao,Liu, Shiwei
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