46 research outputs found
Transformation of Au<inf>144</inf>(SCH<inf>2</inf>CH<inf>2</inf>Ph)<inf>60</inf> to Au<inf>133</inf>(SPh- t Bu)<inf>52</inf> Nanomolecules: Theoretical and experimental study
Ultrastable gold nanomolecule Au144(SCH2CH2Ph)60 upon etching with
excess tert-butylbenzenethiol undergoes a core-size conversion and compositional change to
form an entirely new core of Au133(SPh-tBu)52. This conversion was studied using highresolution
electrospray mass spectrometry which shows that the core size conversion is
initiated after 22 ligand exchanges, suggesting a relatively high stability of the
Au144(SCH2CH2Ph)38(SPh-tBu)22 intermediate. The Au144 \u2192 Au133 core size conversion
is surprisingly different from the Au144 \u2192 Au99 core conversion reported in the case of
thiophenol, 12SPh. Theoretical analysis and ab initio molecular dynamics simulations show
that rigid p-tBu groups play a crucial role by reducing the cluster structural freedom, and
protecting the cluster from adsorption of exogenous and reactive species, thus rationalizing the kinetic factors that stabilize the
Au133 core size. This 144-atom to 133-atom nanomolecule\u2019s compositional change is reflected in optical spectroscopy and
electrochemistry