Showing papers by "Arun Kumar Sinha published in 2012"
TL;DR: In this article, the formation of AuF is carefully studied, and a spontaneous assembly mechanism is proposed, and the time-course experimental results show that the influence of electrostatic field force (EFF) of the charged resin beads is held responsible for prickly tipped AuF formation.
Abstract: Highly branched Au flowers (AuFs) with sharp tips have been synthesized in high yield by controlling the kinetics of nanocrystal growth via galvanic replacement reaction. Controlled galvanic replacement takes place on appropriately chosen commercially available polystyrene bead supported Cu nanoparticles with HAuCl4. Such a reaction is thermodynamically driven through the exploitation of a Cu(II)/Cu(0) redox couple during nanocrystal formation. The hierarchical morphology of the resulting naked Au flowers (AuFs) depends on the galvanic exchange rate, which increases with increasing HAuCl4 concentration but over a specific concentration range. The formation of AuF is carefully studied, and a spontaneous assembly mechanism is proposed. The time-course experimental results show that the influence of electrostatic field force (EFF) of the charged resin beads is held responsible for prickly tipped AuF formation. Then the fabrication of AuF morphology becomes a large-scale free-standing synthetic protocol for a...
77 citations
TL;DR: In this paper, a truncated cubic Cu2O cubes with well-defined morphology have been successfully synthesized using a stable Cu(II)-EDTA precursor and glucose as the reducing agent in alkaline conditions under 5 min of microwave irradiation.
Abstract: Truncated Cu2O cubes with well-defined morphology have been successfully synthesized using a stable Cu(II)–EDTA precursor and glucose as the reducing agent in alkaline conditions under 5 min of microwave irradiation. The truncated cubic Cu2O particles as a solid powder were characterized by different physical methods. Curiously enough, upon the addition of Cu2O particles, the blue-colored methylene blue (MB) in aqueous acidic (pH ≈ 1.0) solution successively bleaches to colorless leuco-MB (LMB). The redox reaction generates a colorless solution which easily reverts back to blue in air. The reaction has been quantitatively monitored by UV–vis spectrophotometry. The reversible color change, i.e., oscillation between a blue MB solution and colorless LMB solution happens to be a periodic phenomenon for more than 50 cycles and is reproducibly demonstrated as a simple “clock reaction”. Acidic (pH ≈ 3.0) conditions favor zeroth-order kinetics for the underlying redox phenomena. Dilute H2SO4 has been proven to be...
53 citations
TL;DR: The surface-enhanced Raman spectra of a bifunctional Raman reporter, 2-mercaptobenzimidazole, has been found to be responsive exclusively towards Cu(2+) ions while the reporter remains anchored on the Au nanoparticle surface, and a specific Cu( 2+)-ion-detection protocol emerges.
Abstract: In the present study, surface-enhanced Raman spectra of a bifunctional Raman reporter, 2-mercaptobenzimidazole, has been found to be responsive exclusively towards Cu2+ ions while the reporter remains anchored on the Au nanoparticle surface. Thus a specific Cu2+-ion-detection protocol emerges. The simplicity, sensitivity, and reproducibility of the method allow routine and quantitative detection of Cu2+ ions. An interference study involving a wide number of other metal ions shows the procedure to be uniquely selective and analytically rigorous. A theoretical study was carried out to corroborate the experimental results. Finally, the method is promising for real-time assessment of Cu2+ ions in aqueous samples and also has the ability to discriminate CuI and CuII ions in solution.
46 citations
TL;DR: In this article, a variety of important hydroxy-functionalized classes of compounds are prepared under microwave-assisted conditions, and a number of them are shown to work well under microwave conditions.
Abstract: A variety of important hydroxy-functionalized classes of compounds is prepared under microwave-assisted conditions.
1 citations