Kinetics and Mechanisms of Aggregative Nanocrystal Growth

Wang, Fudong; Richards, Vernal N.; Shields, Shawn P.; Buhro, William E.

doi:10.1021/cm402139r

Cited by 448 publications

(483 citation statements)

References 197 publications

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“…At remarked by Wang: [113] Christopher Ingold, a major early contributor to mechanistic organic chemistry, astutely foreshadowed the future development of organic synthesis in the following statement: [114,115] "The new work made it inescapably clear that the old order in organic chemistry was changing, the art of the subject diminishing, its science increasing: no longer could one just mix things; sophistication in physical chemistry was the base from which all chemists, including the organic chemist, must start." The current state of the understanding of chemical reactivity is comparable to that of organic synthesis a century ago.…”

Section: Discussionmentioning

confidence: 99%

Unraveling reaction mechanisms by means of Quantum Chemical Topology Analysis

Andrés

González-Navarrete

Safont

2014

Int J of Quantum Chemistry

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A chemical reaction can be understood in terms of geometrical changes of the molecular structures and reordering of the electronic densities involved in the process; therefore, identifying structural and electronic density changes taking place along the reaction coordinate renders valuable information on reaction mechanism. Understanding the atomic rearrangements that occur during chemical reactions is of great importance, and this perspective aims to highlight the major developments in quantum chemical topology analysis, based on the combination of electron localization function and catastrophe theory as useful tools in elucidating the bonding and reactivity patterns of molecules. It reveals all the expected, but still ambiguous, elements of electronic structure extensively used by chemists. The chemical bonds determine chemical reactivity, and this technique offers the possibility of their visualization, allowing chemists to understand how atoms bond, how and where bonds are broken/ formed along a given reaction pathway at a most fundamental level, and so, better following and understanding the changes in the bond pattern. Their results clearly herald a new era, in which the atomic imaging of chemical bonds will constitute a new method for examining chemical structures and reaction mechanisms. The important feature of this procedure is that in practice the scope of its values is systemindependent. In addition, from a practical point of view, it is cheap to calculate and implement because wave functions are the required input, which are easily available from standard calculations. To capture these results two reaction mechanisms: isomerization of C(BH) 2 carbene and the thermal cycloheptatriene-norcaradiene isomerizations have been selected, indicating both the generality and utility of this type of analysis.

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Section: Discussionmentioning

confidence: 99%

Unraveling reaction mechanisms by means of Quantum Chemical Topology Analysis

Andrés

González-Navarrete

Safont

2014

Int J of Quantum Chemistry

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“…This model applies to specific solid-state phase transformations. However, it has also been used to fit other nucleation-and-growth processes exhibiting sigmoidal conversion kinetics, such as crystal formation from solution and melts [21,22]. For solid-state phase transformations, the value of n is usually related to the mechanism of nucleation and the dimensionality of growth.…”

Section: Saxs and Waxs Data Processingmentioning

confidence: 99%

Physicochemical and Additive Controls on the Multistep Precipitation Pathway of Gypsum

et al. 2017

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Synchrotron-based small-and wide-angle X-ray scattering (SAXS/WAXS) was used to examine in situ the precipitation of gypsum (CaSO 4 ·2H 2 O) from solution. We determined the role of (I) supersaturation, (II) temperature and (III) additives (Mg 2+ and citric acid) on the precipitation mechanism and rate of gypsum. Detailed analysis of the SAXS data showed that for all tested supersaturations and temperatures the same nucleation pathway was maintained, i.e., formation of primary particles that aggregate and transform/re-organize into gypsum. In the presence of Mg 2+ more primary particle are formed compared to the pure experiment, but the onset of their transformation/reorganization was slowed down. Citrate reduces the formation of primary particles resulting in a longer induction time of gypsum formation. Based on the WAXS data we determined that the precipitation rate of gypsum increased 5-fold from 4 to 40 • C, which results in an effective activation energy of~30 kJ·mol −1 . Mg 2+ reduces the precipitation rate of gypsum by more than half, most likely by blocking the attachment sites of the growth units, while citric acid only weakly hampers the growth of gypsum by lowering the effective supersaturation. In short, our results show that the nucleation mechanism is independent of the solution conditions and that Mg 2+ and citric acid influence differently the nucleation pathway and growth kinetics of gypsum. These insights are key for further improving our ability to control the crystallization process of calcium sulphate.

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“…11 Nevertheless, the resemblance to reactant-induced Ostwald ripening and disintegration of metal nanoparticles is intriguing. [12][13] Moreover, examples are restricted to less reactive gold and silver NCs; copper NCs with metallic character are significantly rarer due to their much higher susceptibility to oxidation. In fact, to our knowledge, only two such complexes are known, namely, [(Cp*AlCu) 6 H 4 ] and [Cu 25 H 22 (PPh 3 ) 12 ]Cl (1).…”

Section: Introductionmentioning

confidence: 99%

Ligand-Exchange-Induced Growth of an Atomically Precise Cu₂₉ Nanocluster from a Smaller Cluster

et al. 2016

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ABSTRACT:The copper hydride nanocluster (NC) [Cu 29 Cl 4 H 22 (Ph 2 phen) 12 ]Cl (2; Ph 2 phen = 4,7-diphenyl-1,10-phenanthroline) was isolated cleanly, and in good yields, by controlled growth from the smaller NC, [Cu 25 H 22 (PPh 3 ) 12 ]Cl (1), in the presence of Ph 2 phen and a chloride source at room temperature. Complex 2 was fully characterized by singlecrystal X-ray diffraction, XANES, and XPS, and represents a rare example of an N* = 2 superatom. Its formation from 1 demonstrates that atomically precise copper clusters can be used as templates to generate larger NCs that retain the fundamental electronic and bonding properties of the original cluster. A time-resolved kinetic evaluation of the formation of 2 reveals that the mechanism of cluster growth is initiated by rapid ligand exchange. The slower extrusion of CuCl monomer, its transport, and subsequent capture by intact clusters, resemble elementary steps in the reactant-assisted Ostwald ripening of metal nanoparticles.

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Kinetics and Mechanisms of Aggregative Nanocrystal Growth

Cited by 448 publications

References 197 publications

Unraveling reaction mechanisms by means of Quantum Chemical Topology Analysis

Unraveling reaction mechanisms by means of Quantum Chemical Topology Analysis

Physicochemical and Additive Controls on the Multistep Precipitation Pathway of Gypsum

Ligand-Exchange-Induced Growth of an Atomically Precise Cu₂₉ Nanocluster from a Smaller Cluster

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Kinetics and Mechanisms of Aggregative Nanocrystal Growth

Cited by 448 publications

References 197 publications

Unraveling reaction mechanisms by means of Quantum Chemical Topology Analysis

Unraveling reaction mechanisms by means of Quantum Chemical Topology Analysis

Physicochemical and Additive Controls on the Multistep Precipitation Pathway of Gypsum

Ligand-Exchange-Induced Growth of an Atomically Precise Cu29 Nanocluster from a Smaller Cluster

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Ligand-Exchange-Induced Growth of an Atomically Precise Cu₂₉ Nanocluster from a Smaller Cluster