609-24-5Relevant articles and documents
One pot green synthesis of polyaniline coated gold nanorods and its applications
Mondal, Sanjoy,Rana, Utpal,Ranjan Bhattacharjee, Rama,Malik, Sudip
, p. 57282 - 57289 (2014)
Morphology controlled high aspect ratio worm-like polyaniline (PANI) layer coated Au-nanostructures (Au/PANI) have been successively synthesized by in situ polymerisation techniques using aniline as a monomer with HAuCl4 as an oxidising agent in the absence and presence of citric acid (CA). Synthesized composites were characterized by HRTEM, FESEM, XRD, XPS, UV-vis and FTIR study. Spherical morphologies are seen in the absence of CA and Au nanoparticles are coated by a PANI thin layer with ～30 nm thickness. In the presence of CA, as well as depending upon the CA to aniline molar ratio, morphology varies from irregular assembly to regular fiber to spherical-like nanostructures. The nanostructures show fibrous morphology with an average diameter of ～100 nm and lengths of more than 5 μm when CA to aniline molar ratios are 1.0 and 0.2. When the ratios are 2.0 and 0.1, the nanostructure represents the granularlike morphology. Nanofiber formation takes place by the assembly of the CA capped tiny Au-nanorods in the presence of aniline during the polymerisation, and all Au-nanorods are finely coated by a PANI thin layer of ～5 nm thickness. Importantly, fibrous Au/PANI nanostructures show superior catalytic activity compared to spherical/irregular Au/PANI nanostructures towards the reduction of toxic aromatic nitro compounds like 4-nitrophenol (4-NP), 4-nitroaniline (4-NA), 2,4-dinitrophenol (2,4-DNP) and 2,4,6-trinitrophenol (2,4,6-TNP). This is because of the coating thickness of PANI over Au-nanoparticles in fibrous Au/PANI nanostructures as well as enhanced surface area.
Catalytic hydrogenation of nitrophenols and nitrotoluenes over a palladium/graphene nanocomposite
Sun, Jingwen,Fu, Yongsheng,He, Guangyu,Sun, Xiaoqiang,Wang, Xin
, p. 1742 - 1748 (2014)
We report a stable palladium/graphene (Pd/G) nanocomposite with differing Pd content for use in the catalytic hydrogenation of nitrophenols and nitrotoluenes. Various microscopic and spectroscopic techniques were employed to characterize the as-prepared catalysts. Catalytic hydrogenation reactions of nitrophenols were conducted in aqueous solution by adding NaBH4, while the nitrotoluene hydrogenation was carried out in methanol in the presence of H2 because of the poor solubility in water. The Pd/G hybrids exhibited much higher activity and higher stability than the commercial Pd/C. Due to the presence of a large excess of NaBH4 compared to p-nitrophenol, the kinetic data can be explained by the assumption of a pseudo-first-order reaction with regard to p-nitrophenol. The resulting high catalytic activity can be attributed to the graphene sheets' strong dispersion effect for Pd nanoparticles and good adsorption ability for nitrobenzene derivatives via π-π stacking interactions. A plausible mechanism is proposed. Considering inductive and conjugation effects that may affect the reactions, the reactivity of nitrophenols in this study is expected to follow the order m-NP > o-NP > p-NP > 2,4-DNP > 2,4,6-TNP, which is in good agreement with the experimental results. This journal is the Partner Organisations 2014.
Switchable Bifunctional Bistate Reusable ZnO-Cu for Selective Oxidation and Reduction Reaction
Sarmah, Kasturi,Mukhopadhyay, Subhamoy,Maji, Tarun K.,Pratihar, Sanjay
, p. 732 - 745 (2019/01/11)
Herein we disclosed the utilization of copper loaded zinc oxide (ZnO-Cu) for its stimuli (O2/light) responsive switchable performance between its reduced (S-1) and oxidized (S-2) state for two antagonistic reactions, namely oxidation of alkyl arenes/heteroarenes to aldehydes/ketones and reduction of nitro arenes/heteroarenes to corresponding amines. The two states of the catalyst showed its switchable performance as highly active and poorly active catalyst for oxidation and reduction, and both reactions could be turned "off" and "on" by changing the stimuli (light and O2/N2). The switching efficiency between the states and their relative reactivity were found to be consistent under variety of reaction conditions and remain unaltered irrespective of oxidation-reduction (or vice versa) sequence and substrates used in the reaction. The photo catalysts (S-1 and S-2) demonstrated good catalytic activity, multiple reusability, broad substrate scope, and reasonable functional group tolerance for both the reactions and probed its quality performance in a large-scale setup. The system was used in an assisted tandem catalysis setup for the synthesis of benzyl amines utilizing both oxidation and reduction reaction by stimuli responsive switching between the states of the catalyst.
An easily accessible and recyclable copper nanoparticle catalyst for the solvent-free synthesis of dipyrromethanes and aromatic amines
Megarajan, Sengan,Ayaz Ahmed, Khan Behlol,Rajmohan, Rajamani,Vairaprakash, Pothiappan,Anbazhagan, Veerappan
, p. 103065 - 103071 (2016/11/13)
A facile method to prepare a reusable copper nanocatalyst is reported. Transmission electron microscopy shows that the CuNPs are spherical in nature and reside in the nanoscopic template of the capping agent, guar gum. Powder X-ray diffraction studies confirm the crystalline nature of the CuNPs. The catalytic efficiency and recyclability of the synthesized CuNPs were demonstrated through the synthesis of dipyrromethanes (DPMs) and aromatic amines. Various DPMs are obtained in very good yields under solvent-free conditions and nitroarenes are converted to the corresponding amino compounds within 10 min, as evidenced by the kinetic study.
