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Core Size Conversion: Route for Exclusive Synthesis of Au38 or Au40 Nanomolecules
journal contribution
posted on 2014-03-11, 00:00 authored by Praneeth
Reddy Nimmala, Vijay Reddy Jupally, Amala DassGold nanomolecules with a precise
number of gold atoms and ligands
have promise for catalytic, optical, and biomedical applications.
For practical applications, it is essential to develop synthetic protocols
to prepare monodisperse gold nanomolecules. A typical synthesis yields
a number of nanomolecules with discrete numbers of core atoms. Thermochemical
treatment in the presence of excess thiol, etching, is known to narrow
down the number of discrete nanomolecules, by selective degradation
of sizes with lower stability. Au38(SR)24 and
Au40(SR)24 are abundantly formed in these etching
reactions due to their extraordinary stability to chemical etching.
These nanomolecules are of high interest due in part to its stability,
X-ray crystallographic structure availability (Au38), and
intrinsic chirality arising from the arrangement of the Au-SR interface.
However, the synthetic routes typically yield a mixture of Au38 and Au40, demanding extensive separation protocols.
Here, we present a synthetic route to prepare either Au38 or Au40 exclusively in the product of etching. This was
made possible by conducting a comprehensive mechanistic study starting
from single-sized reactant. Au67 on etching yields Au40 exclusively. Au103–105(SR)45–46 on etching also yields Au40 exclusively. Clusters of
various sizes smaller than Au67 on etching yield Au38 exclusively. This is the first direct evidence for the exclusive
formation of Au38 and Au40 nanomolecules by
core size conversion. Mass spectrometry was used to study the core
size conversion reactions to understand the mechanism. Au38 and Au40 nanomolecules form via different intermediates,
as observed in the mass spectrometry data.
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- Biophysics
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- Cell Biology
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- Developmental Biology
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Keywords
mass spectrometrysynthesis yieldsstructure availabilitycore Size ConversionExclusive Synthesisstabilitycore atomsmass spectrometry datagold nanomoleculesetching reactionsetching yieldscore size conversion reactionsseparation protocolsgold atomscore size conversion40 nanomolecules formThermochemical treatment40 nanomoleculeschemical etching40 NanomoleculesGold nanomolecules
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