Liquid Metastable Precursors of Ibuprofen as Aqueous Nucleation Intermediates

Wiedenbeck, Eduard; Kovermann, Michael; Gebauer, Denis; Cölfen, Helmut

doi:10.1002/anie.201910986

Cited by 52 publications

(68 citation statements)

References 37 publications

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“…The multistep model, designated by nonclassical nucleation theory, accounts for the presence of intermediates in the pre-nucleation stage . Such intermediates have been illustrated in several materials systems including calcium-based inorganics [4][5][6][7][8] , organics [9][10][11] , polymers [12][13][14] , metals [15][16][17] , and semiconductor quantum dots (QDs) [18][19][20][21][22][23][24][25][26][27][28] .…”

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confidence: 99%

Room-temperature formation of CdS magic-size clusters in aqueous solutions assisted by primary amines

et al. 2020

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Aqueous-phase approaches to semiconductor CdS magic-size clusters (MSCs) and the formation pathway have remained relatively unexplored. Here, we report the demonstration of an aqueous-phase, room-temperature approach to CdS MSCs, together with an exploration of their evolution pathway. The resulting CdS MSCs display a sharp optical absorption peak at about 360 nm and are labeled MSC-360. With CdCl 2 and thiourea as the respective Cd and S sources, and 3-mercarpotopropionic acid as the ligand, CdS MSC-360 develops in a mixture of a primary amine and water. We argue that the primary amine facilitates roomtemperature decomposition of thiourea when CdCl 2 is present, and the formation pathway of MSCs is similar to that in organic-phase approaches. Our findings show there is a viable avenue to room-temperature aqueous-phase formation of CdS MSCs. Providing explanations of the procedure developed including the formation of large aggregates, the present study represents an important advance towards a mechanistic understanding of nanocrystal synthesis.

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confidence: 99%

Room-temperature formation of CdS magic-size clusters in aqueous solutions assisted by primary amines

et al. 2020

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“…The advance in the synthesis of quantum dots, resulting in an in‐depth understanding of the induction period described by the two‐pathway model, facilitates the control of size and particle yield of quantum dots, and thus embraces the promise of colloidal semiconductor quantum dots in various application areas . Furthermore, this two‐pathway model reinforces the multistep nucleation model which has been proposed for several other material systems including organics, polymers, inorganics, and metals …”

Section: Introductionmentioning

confidence: 52%

“…Also, the present study provides a more complete understanding of the evolution of MSCs and the transformations among them . Similar to the fabrication of small‐size CdS quantum dots with enhanced particle yield from a CdS induction period sample, the room‐temperature synthesis of single‐ensemble CdTeSe MSC‐399 by mixing CdTe and CdSe induction period samples assists in the advance of nonclassical nucleation theory …”

Section: Introductionmentioning

confidence: 84%

Room‐Temperature Formation Pathway for CdTeSe Alloy Magic‐Size Clusters

et al. 2020

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Little is known about the pathway of room‐temperature formation of ternary CdTeSe magic‐size clusters (MSCs) obtained by mixing binary CdTe and CdSe induction period samples containing binary precursor compounds (PCs) of MSCs, monomers (Ms), and fragments (Fs). Also, unestablished are dispersion effects that occur when as‐mixed samples (without incubation) are placed in toluene (Tol) and octylamine (OTA) mixtures. The resulting ternary MSCs, exhibiting a sharp optical absorption peak at 399 nm, are labelled CdTeSe MSC‐399, and their PCs are referred to as CdTeSe PC‐399. When the amount of OTA is relatively small, single‐ensemble MSC‐399 evolved without either binary CdTe or CdSe MSCs. When the OTA amount is relatively large, CdTe MSC‐371 appeared initially and then disappeared, while single‐ensemble MSC‐399 developed more deliberately. The larger the OTA amount, the more slowly these changes proceeded. The substitution reaction of CdTe PC + CdSe M/F↔CdTeSe PC‐399 + CdTe M/F is proposed to be rate‐determining for the MSC‐399 formation in a Tol and OTA mixture. This study provides further understanding of the transformation pathway between MSCs.

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“…FFA, where the molecules are in a higher concentration compared to the mother solution. As such, in the DLP the molecules are hindered in their translational and rotational movements and kinetically stable (metastable) whilst still possessing an interface with the surrounding liquid 9 .…”

Section: Resultsmentioning

confidence: 99%

Non-classical crystallisation pathway directly observed for a pharmaceutical crystal via liquid phase electron microscopy

Cookman

Hamilton

Hall

et al. 2020

Sci Rep

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Non-classical crystallisation (NCC) pathways are widely accepted, however there is conflicting evidence regarding the intermediate stages of crystallisation, how they manifest and further develop into crystals. Evidence from direct observations is especially lacking for small organic molecules, as distinguishing these low-electron dense entities from their similar liquid-phase surroundings presents signal-to-noise ratio and contrast challenges. Here, Liquid Phase Electron Microscopy (LPEM) captures the intermediate pre-crystalline stages of a small organic molecule, flufenamic acid (FFA), a common pharmaceutical. High temporospatial imaging of FFA in its native environment, an organic solvent, suggests that in this system a Pre-Nucleation Cluster (PNC) pathway is followed by features exhibiting two-step nucleation. This work adds to the growing body of evidence that suggests nucleation pathways are likely an amalgamation of multiple existing non-classical theories and highlights the need for the direct evidence presented by in situ techniques such as LPEM.

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Liquid Metastable Precursors of Ibuprofen as Aqueous Nucleation Intermediates

Cited by 52 publications

References 37 publications

Room-temperature formation of CdS magic-size clusters in aqueous solutions assisted by primary amines

Room-temperature formation of CdS magic-size clusters in aqueous solutions assisted by primary amines

Room‐Temperature Formation Pathway for CdTeSe Alloy Magic‐Size Clusters

Non-classical crystallisation pathway directly observed for a pharmaceutical crystal via liquid phase electron microscopy

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