Selective Catalysis and Nanoscience: An Inseparable Pair

Biradar

et al. 2010

Chemistry A European J

We report a solution-phase synthetic route to copper nanoparticles with controllable size and shape. The synthesis of the nanoparticles is achieved by the reduction of copper(II) salt in aqueous solution with hydrazine under air atmosphere in the presence of poly(acrylic acid) (PAA) as capping agent. The results suggest that the pH plays a key role for the formation of pure copper nanoparticles, whereas the concentration of PAA is important for controlling the size and geometric shape of the nanoparticles. The average size of the copper nanoparticles can be varied from 30 to 80 nm, depending on the concentration of PAA. With a moderate amount of PAA, faceted crystalline copper nanoparticles are obtained. The as-synthesized copper nanoparticles appear red in color and are stable for weeks, as confirmed by UV/Vis and X-ray photoemission (XPS) spectroscopy. The faceted crystalline copper nanoparticles serve as an effective catalyst for N-arylation of heterocycles, such as the C--N coupling reaction between p-nitrobenzyl chloride and morpholine producing 4-(4-nitrophenyl)morpholine in an excellent yield under mild reaction conditions. Furthermore, the nanoparticles are proven to be versatile as they also effectively catalyze the three-component, one-pot Mannich reaction between p-substituted benzaldehyde, aniline, and acetophenone affording a 100% conversion of the limiting reactant (aniline).

Section: Resultsmentioning

confidence: 99%

Controlled Synthesis of Water‐Dispersible Faceted Crystalline Copper Nanoparticles and Their Catalytic Properties

Biradar

et al. 2010

Chemistry A European J

“…NST applications are highly knowledge intensive, as most of the sectors where they take place-for instance catalysts (Zecchina et al 2007;Evangelisti et al 2007) or biomaterials Celotti et al 2006)-still rely much on the results of basic research. This fact has attracted towards NST the attention of scientists engaged in studies of Organization and Management, Economics, Innovation Studies.…”

Section: An Overview On the History Of Nanotechnologies And Of Polymersmentioning

confidence: 99%

Time relations between scientific production and patenting of knowledge: the case of nanotechnologies

Finardi

2011

Scientometrics

Nanosciences and nanotechnologies are considered important for the development of science, technology and innovation, and the study of their characters can be a great help to the decisions of policy makers and of practitioners. This work is centred on the issue of the time relations between science and technology/innovation, and in particular on the speed of transfer of science-generated knowledge towards its exploitation in patenting. A methodology based on patent citations is used in order to measure the time lag between cited journal articles and citing patent, and thus the time proximity between the two steps. Keywords regarding nanotechnology/nanoscience items are searched in order to collect data useful for the analysis. Collateral measures, performed on another class of materials and on the spatial origin of citing/cited documents, help giving evidence of the peculiarity of the behaviour and on its nature. The most representative time lag between production of scientific knowledge and its technological exploitation appears being around 3-4 years.

“…The shape is another parameter of key importance to control the properties of such nanoparticles as the motion of electrons (and therefore holes and plasmons) can be confined in given directions. For example, not only the catalytic activity of metals is enhanced when their size is reduced, 3,4 but the selectivity of the catalyzed reactions is also strongly dependent on the exposed facets, and therefore on the shape of the nanocrystals (NCs). 5,6 Besides, the surface plasmon resonance (SPR) in Au NCs is mostly dependent on their shape: 7 changing the geometry of the nanocrystal changes the energy of the plasmon peak more than the mere increase of the size of the spherical particles.…”

Section: Introductionmentioning

confidence: 99%

Two-Dimensional Colloidal Nanocrystals

et al. 2016

Abstract:In this paper, we review recent progresses on colloidal growth of 2D nanocrystals.We identify four main sources of anisotropy which lead to the formation of plate-and sheetlike colloidal nanomaterials. Defect induced anisotropy is a growth method which relies on the presence of topological defects at the nanoscale to induce 2D shapes objects. Such a method is particularly important in the growth of metallic nanoobjects. Another way to induce anisotropy is based on ligand engineering. The availability of some nanocrystal facets can be tuned by selectively covering the surface with ligands of tunable thickness. Cadmium chalcogenides nanoplatelets (NPLs) strongly rely on this method which offers atomic control in the thinner direction, down to a few monolayers. 2D objects can also be obtained by post or in situ self-assembly of nanocrystals. This growth method differs from the previous ones in the sense that the elementary objects are not molecular precursors, and is a common method for lead chalcogenide compounds. Finally, anisotropy may simply rely on the lattice anisotropy itself as it is common for rod-like nanocrystals. Colloidally grown Transition Metal DiChalcogenides (TMDC) in particular result from such process. We also present hybrid syntheses which combine several of the previously described methods and other paths, such as cation exchange, which expand the range of available materials. Finally, we discuss in which sense 2D-objects differ from 0D nanocrystals and review some of their applications in optoelectronics, including lasing and photodetection, and biology.