95-86-3Relevant academic research and scientific papers
Synthesis of magnetic silver cyclodextrin nanocomposite as catalyst for reduction of nitro aromatics and organic dyes
Nariya, Pratik,Das, Manita,Shukla, Falguni,Thakore, Sonal
, (2020)
Nanocomposites decorated with metallic nanoparticles in their matrix are important class of heterogeneous catalyst with high catalytic activity. Functionalized polymers are low cost materials which offer excellent supports for catalysts to render stability to metallic nanoparticles. Herein we report synthesis of Silver nanocomposite using β-cyclodextrin (b-CD) maleic anhydride crosslinked polymer anchored on the surface of magnetic nanoparticles. The nanocomposite was characterized using sophisticated analytical techniques and its role as a catalyst for reduction of nitroaromatics and organic dyes was investigated. This catalytic system exhibited comparatively lower Ea value of 18 kJ mol?1 and followed pseudo first order kinetics. Simultaneous reduction of 4-Nitrophenol and Methylene Blue could be achieved in a time interval of 7 minutes. Being magnetically separable, the catalyst exhibited high recycling efficiency (up to 5 cycles) and ease of operation under mild conditions.
Porous noria polymer: a cage-to-network approach toward a robust catalyst for CO2fixation and nitroarene reduction
Giri, Arkaprabha,Patil, Niraj Nitish,Patra, Abhijit
, p. 4404 - 4407 (2021)
The advantages of the cage-to-network design strategy were demonstrated by knitting a waterwheel-like preporous molecular cage, noria, with a rigid aromatic linker to obtain a highly microporous organic polymer (NPOP,SBET: 748 ± 25 m2g?1). The NPOP was employed for the catalytic conversion of CO2to cyclic carbonates under solvent-free reaction conditions. Furthermore, a silver nanoparticle encapsulated NPOP exhibited remarkable catalytic activity for nitroarene reduction with excellent recyclability.
Synthesis of graphene quantum dots stabilized bimetallic AgRh nanoparticles and their applications
Li, Ning,Chen, Weifeng,Shen,Chen, Shaona,Liu
, (2019)
The design and synthesis of highly efficient and ultrafine bimetallic nanoparticles catalysts is challenging. Here we report the synthesis of AgRh bimetallic nanoparticles (AgRh BNPs) stabilized by graphene quantum dots (GQDs) and their exceptional catalytic activities in the reduction of 4-nitrophenol, 2,4-dinitrophenol and 4-nitrobenzene diazonium tetrafluoroborate and generation of hydroxyl radicals. Construction of AgRh BNPs nanocomposites is accomplished by mixing of GQDs and sodium borohydride, followed by the addition of simple commercial Ag and Rh salt at 0 °C in water. Among them, AgRh BNPs 4 exhibits excellent catalytic performance owing to a positive synergistic effects between the Ag and Rh atoms on GQDs, and its catalytic activity is better than those of both monometallic counterparts.
Yolk@Shell Nanoreactors Carrying a Cluster of Metal Nanocrystals Stabilized Inside the Hollow Carbon Shell
Acharya, Anubhab,Kumar, Amit,Lee, In Su
, p. 915 - 918 (2021)
Synthesis and stabilization of ultrasmall metal nanocrystals at high temperature have always been challenging due to their self-aggregating behavior. Here, we introduce a strategy to synthesize a cluster of tiny metal nanocrystals (~3 nm) inside a hollow carbon shell as yolk@shell-type architecture following a metal-coordination-based nanocrystal stabilization at high temperature (500?°C). The successful catalytic reduction of 2-amino-4-nitrophenol demonstrates the efficiency of such nanoreactor in chemical transformation. Further adaptation of this strategy helps in synthesizing bimetallic (Au/Pt, Au/Pd, and Au/Ru) nanocrystals, which unfolds the possibilities to design advanced new-generation catalysts.
Galactose Grafted Two-Dimensional Nanosheets as a Scaffold for the In Situ Synthesis of Silver Nanoparticles: A Potential Catalyst for the Reduction of Nitroaromatics
Harikrishnan, Kaloor S.,Krishnan, Nithiyanandan,Kumar, Nilima Manoj,Krishna, Anusree,Raj, Gowtham,Perumal, Devanathan,Kalathil, Jemshiya,Krishna, Jithu,Varghese, Reji
, p. 14100 - 14107 (2021/09/06)
Two major hurdles in NP-based catalysis are the aggregation of the NPs and their recycling. Immobilization of NPs onto a 2D support is the most promising strategy to overcome these difficulties. Herein, amphiphilicity-driven self-assembly of galactose-hexaphenylbenzene-based amphiphiles into galactose-decorated 2D nanosheet is reported. The extremely dense decoration of reducing sugar on the surface of the sheets is used for the in situ synthesis and immobilization of ultrafine catalytically active AgNPs by using Tollens’ reaction. The potential of the system as a catalyst for the reduction of various nitroaromatics is demonstrated. Enhanced catalytic activity is observed for the immobilized AgNPs when compared to the corresponding discrete AgNPs. Recovery of the catalytic system from the reaction mixture by ultrafiltration and its subsequent recycling for several cycles without dropping its activity is shown. This is the first report demonstrating the in situ synthesis and immobilization of ultrafine AgNPs onto a 2D nanosheet that exhibits excellent catalytic performance for the reduction of nitroaromatics.
Record-high catalytic hydrogenated activity in nitroarenes reduction derived from in-situ nascent active metals enabled by constructing bimetallic phosphate
Yang, Fu,Wang, Jin,Gao, Shuying,Zhou, Shijian,Kong, Yan
, (2020/03/10)
Herein, we report an excellent in-situ exsolution triggered hydrogenated catalyst F-Ni/Cu-P-RT started from bimetallic phosphate Ni/Cu-P-RT, affording an ultrafast catalytic hydrogenated rate (20 s even 5 s) in nitrophenol reduction. In the first catalytic cycle, we proved the enhanced catalytic reduction activity of bimetallic Ni/Cu-P-RT within 50 s compared to monometallic counterparts. The kinetics results revealed Ni/Cu-P-RT affords the reaction rate K of 2.85/4.23/6.6 min?1 at 20, 30, and 40 °C with the activation energy 32 kJ/mol. Impressively, the involved reaction induction period is visibly observed and interpreted by reconstruction and evolution of active metal during the reaction, but was eliminated through integrating two metal Cu-Ni by regulation of electronic band energy of phosphate from 4.1–3.5 eV. The nascent Cu and Ni nanoparticles as reaction-preferred active species were in-situ exsolved partially after adding NaBH4, triggering the resulted higher active and stable F-Ni/Cu-P-RT(20 s, 14.1 min?1) in later multiple cycles.
Chemoselective reduction of nitro and nitrile compounds using an Fe3O4-MWCNTs?PEI-Ag nanocomposite as a reusable catalyst
Ansari, Sara,Khorshidi, Alireza,Shariati, Shahab
, p. 3554 - 3565 (2020/02/04)
Multi-walled carbon nanotubes (MWNTs) were modified with carboxylic acid functional groups (MWCNTs-(COOH)n) prior to decoration with Fe3O4 nanoparticles. A further modification step by polyethyleneimine (PEI) resulted in Fe3O4-MWCNTs?PEI which provided a suitable platform for coordination and in situ reduction of silver ions to obtain an Fe3O4-MWCNTs?PEI-Ag nanocomposite with highly dispersed Ag nanoparticles. The Fe3O4-MWCNTs?PEI-Ag hybrid material was characterized by various techniques such as Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), transmission electron microscopy (TEM), vibrating sample magnetometry (VSM), X-ray photoelectron spectroscopy (XPS) and thermogravimetric analysis (TGA), and was used as an efficient catalyst for chemoselective reduction of nitroaromatic and nitrile compounds to their corresponding amines in aqueous solution at ambient temperature. Nitrofurazone, a cytotoxic antibiotic, as a non-aromatic example was also reduced selectively at the nitro group without reduction of the other functionalities in the presence of Fe3O4-MWCNTs?PEI-Ag. The catalyst was magnetically recoverable and maintained its activity for at least six cycles without considerable loss of efficiency.
A Pd confined hierarchically conjugated covalent organic polymer for hydrogenation of nitroaromatics: Catalysis, kinetics, thermodynamics and mechanism
Awasthi, Satish Kumar,Yadav, Deepika
, p. 4295 - 4303 (2020/07/30)
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.
Pd-Pt/modified GO as an efficient and selective heterogeneous catalyst for the reduction of nitroaromatic compounds to amino aromatic compounds by the hydrogen source
Salahshournia, Hossein,Ghiaci, Mehran
, (2019/02/14)
In this work, different nitroaromatic compounds were successfully reduced to their corresponding aromatic amines with excellent conversion and selectivity in methanol at 50?°C by using Pd-Pt nanoparticles immobilized on the modified grapheme oxide (m-GO) and hydrogen as the reducing source. The catalytic efficiency of Pd and Pd-Pt loading on the modified GO was investigated for the reduction of various nitroaromatic compounds, and the Pd-Pt/m-GO system demonstrated the highest conversion and selectivity. The catalyst was characterized by different techniques including FT-IR, Raman, UV–Vis, XRD, BET, XPS, FESEM, EDS, and TEM. The metal nanoparticles with the size of less than 10?nm were uniformly distributed on the m-GO. The catalyst could be reused at least five times without losing activity, showing the stability of the catalyst structure. Finally, the efficiency of the prepared catalyst was compared with Pd-Pt/AC, and Pd-Pt/GO catalysts.
Synthesis of Ultrafine Silver Nanoparticles on the Surface of Fe3O4@SiO2@KIT-6-NH2 Nanocomposite and Their Application as a Highly Efficient and Reusable Catalyst for Reduction of Nitrofurazone and Aromatic Nitro Compounds Under Mild Conditions
Ansari, Sara,Khorshidi, Alireza,Shariati, Shahab
, p. 410 - 418 (2018/11/23)
Uniform dispersion of ultrafine spherical silver nanoparticles (NPs) was obtained over the surface of Fe3O4@SiO2@KIT-6 core–shell support via functionalization of the mesoporous KIT-6 shell by aminopropyltriethoxysilane, followed by coordination of Ag+ ions and in situ chemical reduction with sodium borohydride. The obtained hybrid material, Fe3O4@SiO2@KIT-6-Ag nanocomposite, was fully characterized by Fourier transform infrared spectroscopy, X-ray diffraction, scanning electron microscopy, and transmission electron microscopy, and used as an efficient catalyst for selective reduction of nitroaromatic compounds in aqueous solution at ambient temperature and neutral pH [nine examples, apparent rate constants at 25?°C, k (min?1), 0.112–0.628]. As a non-aromatic example, nitrofurazone which is a cytotoxic antibiotic was also reduced selectively at nitro group without reduction of other functionalities. Fe3O4@SiO2@KIT-6-Ag NPs also showed potential ability to act as catalyst for reduction of nitromethane in aqueous solution which can provide a colorimetric method for detection of nitromethane in solution down to 0.9 × 10?4?mol?L?1. Fe3O4@SiO2@KIT-6-Ag nanocomposite was also screened for its antibacterial activity, and satisfactory results were obtained in comparison with drug references including Tetracycline, Chloramphenicol and Cefotaxime as positive controls, on gram negative Escherichia coli and Pseudomonas aeroginosa. Ease of recycling of the Fe3O4@SiO2@KIT-6-Ag is another benefit of this nanocatalyst. Under the optimized conditions, the recycled catalyst showed 15% loss of efficiency after five successive runs. Graphical Abstract: [Figure not available: see fulltext.].
