Understanding and Controlling Rotation at the Single-Molecule Level.
Abstract: As technology goes to smaller and smaller dimensions, efficient
parts are needed on the same size scale in order to create nano- and micro-machines. Just
as motors are needed on the macroscale to run engines, motors are needed in these tiny
machines in order to convert a fuel source into productive work. While scientists have had
trouble creating synthetic nano- and micro-scale motors, ... read morethese sorts of "machines" are
prevalent throughout biology. This thesis describes studies into the fundamental properties
of rotating thioether molecules. Symmetric thioethers have been studied in detail as a
function of chain length to clarify the similarities between the rotational barriers for
thioethers with two or more carbons in each alkyl tail. Molecules were electrically-driven
using pulses from the STM tip, and the mechanism for this rotation was elucidated. Using
theoretical methods both the adsorption site and rotational pathway were revealed.
Asymmetric thioethers were studied using both experimental and theoretical methods.
Adsorption site dependent rotational properties were found, and the barrier to rotation was
calculated to have an asymmetric torsional potential. It was discovered that due to the
intrinsic chirality of even bare metal STM tips, that directed rotation could be achieved
in the electrically-induced motion of surface-bound enantiomers. This directed motion shows
for the first time that an electrically-driven rotary motor can be made from a single
Thesis (Ph.D.)--Tufts University, 2011.
Submitted to the Dept. of Chemistry.
Advisor: E. Charles Sykes.
Committee: Arthur Utz, Elena Rybak-Akimova, and Feng Wang.
Keyword: Physical Chemistry.read less
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