1 research outputs found
Unraveling the Interplay of Backbone Rigidity and Electron Rich Side-Chains on Electron Transfer in Peptides: The Realization of Tunable Molecular Wires
Electrochemical studies
are reported on a series of peptides constrained
into either a 3<sub>10</sub>-helix (<b>1</b>ā<b>6</b>) or Ī²-strand (<b>7</b>ā<b>9</b>) conformation,
with variable numbers of electron rich alkene containing side chains.
Peptides (<b>1</b> and <b>2</b>) and (<b>7</b> and <b>8</b>) are further constrained into these geometries with a suitable
side chain tether introduced by ring closing metathesis (RCM). Peptides <b>1</b>, <b>4</b> and <b>5</b>, each containing a single
alkene side chain reveal a direct link between backbone rigidity and
electron transfer, in isolation from any effects due to the electronic
properties of the electron rich side-chains. Further studies on the
linear peptides <b>3</b>ā<b>6</b> confirm the ability
of the alkene to facilitate electron transfer through the peptide.
A comparison of the electrochemical data for the unsaturated tethered
peptides (<b>1</b> and <b>7</b>) and saturated tethered
peptides (<b>2</b> and <b>8</b>) reveals an interplay
between backbone rigidity and effects arising from the electron rich
alkene side-chains on electron transfer. Theoretical calculations
on Ī²-strand models analogous to <b>7</b>, <b>8</b> and <b>9</b> provide further insights into the relative roles
of backbone rigidity and electron rich side-chains on intramolecular
electron transfer. Furthermore, electron population analysis confirms
the role of the alkene as a āstepping stoneā for electron
transfer. These findings provide a new approach for fine-tuning the
electronic properties of peptides by controlling backbone rigidity,
and through the inclusion of electron rich side-chains. This allows
for manipulation of energy barriers and hence conductance in peptides,
a crucial step in the design and fabrication of molecular-based electronic
devices