The Reactions of Hydrogen Atoms in Aqueous Solutions: Thiols

Tung, Tzu-Lin; Kuntz, Robert R.

doi:10.2307/3573807

“…Aqueous electrons sever the C-S bond between the PEG and thiol, creating a reactive alkyl radical at the end of the PEG chain, PEG •. 60,61 PEG − S • species are rapidly oxidized by dissolved oxygen 62 into PEG − SOO • or recombine to form disulfide bridges (PEGS-SPEG). 63 Besides the thiol functional group, hydroxyl radicals readily oxidize the PEG chain via hydrogen abstraction to form alkyl radicals on the PEG chain, PEG • −SH.…”

Section: Radical-ligand Reactionsmentioning

confidence: 99%

Visualizing Ligand-Mediated Bimetallic Nanocrystal Formation Pathways with in Situ Liquid-Phase Transmission Electron Microscopy Synthesis

Wang

¹

,

Leff

²

,

Li

³

et al. 2021

View full text Add to dashboard Cite

Colloidal synthesis of alloyed multimetallic nanocrystals with precise composition control remains a challenge and a critical missing link in theory-driven rational design of functional nanomaterials. Liquid phase transmission electron microscopy (LP-TEM) enables directly visualizing nanocrystal formation mechanisms that can inform discovery of design rules for colloidal multimetallic nanocrystal synthesis, but it remains unclear whether the salient chemistry of the flask synthesis is preserved in the extreme electron beam radiation environment during LPTEM. Here we demonstrate controlled in situ LP-TEM synthesis of alloyed AuCu nanoparticles while maintaining the molecular structure of electron beam sensitive metal thiolate precursor complexes. Ex situ flask synthesis experiments showed that nearly equimolar AuCu alloys formed from heteronuclear metal thiolate complexes, while gold-rich alloys formed in their absence. Systematic dose rate-controlled in situ LP-TEM synthesis experiments established a range of electron beam synthesis conditions that formed alloyed AuCu nanoparticles with similar alloy composition, random alloy structure, and particle size distribution shape as those from ex situ flask synthesis, indicating metal thiolate complexes were preserved under these conditions. Reaction kinetic simulations of radical-ligand reactions revealed that polymer capping ligands acted as effective hydroxyl radical scavengers during LP-TEM synthesis and prevented metal thiolate oxidation at low dose rates. In situ synthesis experiments and ex situ atomic scale imaging revealed that a key role of metal thiolate complexes was to prevent copper atom oxidation and facilitate formation of prenucleation cluster intermediates. This work demonstrates that complex ion precursor chemistry can be maintained during LP-TEM imaging, enabling probing nanocrystal formation mechanisms with LP-TEM under reaction conditions representative of ex situ flask synthesis. File list (2) download file view on ChemRxiv AuCumanuscript_ChemRxiv.pdf (1.69 MiB) download file view on ChemRxiv Supplementary Materials_chemRxiv.pdf (1.08 MiB)

show abstract

“…Hydroxyl and hydrogen radicals abstract hydrogen from the thiol functional groups to form thiyl radicals, PEG − S •. Aqueous electrons sever the C-S bond between the PEG and thiol, creating a reactive alkyl radical at the end of the PEG chain, PEG • 60,61. PEG − S • species are rapidly oxidized by dissolved oxygen62 into PEG − SOO • or recombine to form disulfide bridges (PEGS-SPEG) 63.…”

mentioning

confidence: 99%

Visualizing Ligand-Mediated Bimetallic Nanocrystal Formation Pathways with In Situ Liquid Phase Transmission Electron Microscopy Synthesis

Wang

¹

,

Leff

²

,

Li

³

et al. 2020

Preprint

View full text Add to dashboard Cite

Colloidal synthesis of alloyed multimetallic nanocrystals with precise composition control remains a challenge and a critical missing link in theory-driven rational design of functional nanomaterials. Liquid phase transmission electron microscopy (LP-TEM) enables directly visualizing nanocrystal formation mechanisms that can inform discovery of design rules for colloidal multimetallic nanocrystal synthesis, but it remains unclear whether the salient chemistry of the flask synthesis is preserved in the extreme electron beam radiation environment during LPTEM. Here we demonstrate controlled in situ LP-TEM synthesis of alloyed AuCu nanoparticles while maintaining the molecular structure of electron beam sensitive metal thiolate precursor complexes. Ex situ flask synthesis experiments showed that nearly equimolar AuCu alloys formed from heteronuclear metal thiolate complexes, while gold-rich alloys formed in their absence. Systematic dose rate-controlled in situ LP-TEM synthesis experiments established a range of electron beam synthesis conditions that formed alloyed AuCu nanoparticles with similar alloy composition, random alloy structure, and particle size distribution shape as those from ex situ flask synthesis, indicating metal thiolate complexes were preserved under these conditions. Reaction kinetic simulations of radical-ligand reactions revealed that polymer capping ligands acted as effective hydroxyl radical scavengers during LP-TEM synthesis and prevented metal thiolate oxidation at low dose rates. In situ synthesis experiments and ex situ atomic scale imaging revealed that a key role of metal thiolate complexes was to prevent copper atom oxidation and facilitate formation of prenucleation cluster intermediates. This work demonstrates that complex ion precursor chemistry can be maintained during LP-TEM imaging, enabling probing nanocrystal formation mechanisms with LP-TEM under reaction conditions representative of ex situ flask synthesis.

show abstract

“…The value of 5 thus estimated from the lo-' M solution yields at pH 0.5 is typical of primary sulphydryl compounds such as cysteine and methyl mercaptan (3,12). The mechanism also predicts G(RSSR) = (1 12) [ g c i + g, , + gOH], which is 3.1 molecules per 100 eV for lo-' M RSH, taking into account the solute reactivity (5).…”

Section: Discussionmentioning

confidence: 85%

“…We have therefore reinvestigated the radiation chemistry of aqueous mercaptoethanol. A detailed study of the pH dependence of the hydrogen yields was made, since reaction [lo] (or [I 11- [12]) would significantly augment G(H2) in the pH range 4-7. Hydrogen sulphide, RSSR, and RH (i.e.…”

Section: Introductionmentioning

confidence: 99%

The radiation chemistry of 2-mercaptoethanol

Lal¹

1985

View full text Add to dashboard Cite

MANOHAR LAL and DAVID A. ARMSTRONG.' Can. J. Chem. 63, 30 ( 1 985). Hydrogen, hydrogen sulphide, mercaptoethanol disulphide, and ethanol yields from the radiolysis of 2-mercaptoethanol are consistent with the same mechanism postulated for other sulphydryl-containing molecules. In all cases studied g,, in neutral solution appears to be enhanced ( g H = 0.7-0.9 molecule per 100 eV). However, there is no basis for attributing this to reaction [lo] which was postulated in earlier work:but is not supported by independent data from H atom studies.MANOHAR LAL et DAVID A. ARMSTRONG. Can. J. Chem. 63, 30 (1985). Les rendements en hydrogkne, en sulfure d'hydrogkne, en disulfure de mercaptoCthanol et en Cthanol, obtenus lors de la radiolyse du mercapto-2 Cthanol, sont en accord avec le mecanisme postulC pour d'autres moltcules contenant des groupes sulfhydryles. Dans tous les cas CtudiCs, il semble que la valeur de gH en solution neutre soit augmentCe (gH = 0,7-0,9 molCcule par 100 eV). Toutefois, il n'y a aucune donnCe experimentale qui puisse permettre d'attribuer ce rksultat a la reaction [lo]

show abstract

The Reactions of Hydrogen Atoms in Aqueous Solutions: Thiols

Cited by 11 publications

References 6 publications

Visualizing Ligand-Mediated Bimetallic Nanocrystal Formation Pathways with in Situ Liquid-Phase Transmission Electron Microscopy Synthesis

Visualizing Ligand-Mediated Bimetallic Nanocrystal Formation Pathways with in Situ Liquid-Phase Transmission Electron Microscopy Synthesis

Visualizing Ligand-Mediated Bimetallic Nanocrystal Formation Pathways with In Situ Liquid Phase Transmission Electron Microscopy Synthesis

The radiation chemistry of 2-mercaptoethanol

Contact Info

Product

Resources

About