Molecule movement along a surface Defuse along a prefer directional direction dragged by STM chip on Au surface at 473K Nano-car Shirai, Y., Osgood, A. J., Zhao, Y., Kelly, K. F. & Tour, J. M. Nano Lett. 5, 2330–2334 (2005) Grill, L. et al. Nature Nanotechnol. 2, 95–98 (2007).

Molecule movement along a surface Defuse along a prefer directional direction dragged by STM chip on Au surface at 473K Nano-car =>molecule act only as passive elements Shirai, Y., Osgood, A. J., Zhao, Y., Kelly, K. F. & Tour, J. M. Nano Lett. 5, 2330–2334 (2005) Grill, L. et al. Nature Nanotechnol. 2, 95–98 (2007).

Nanocar+ rotor unit a(2006 model) b(2012 model) STM Image of b on Cu(111) Model of b (calculated) Nano-car don’t move along an Au or Cu surface by UV light pluses(248 nm) irradiation >interaction between wheel and surface is too strong >energy quenched by metal surface a)Morin, J.-F.; Shirai, Y.James M Tour, J. Org. Lett. 2006, 8, 1713– 1716 b)Pinn-Tsong Chiang, Leonhard Grill, and James M. Tour et al ACS Nano, 2012, 6 , 592–597

Electric nanocar Molecular design Exaction way Four rotor unit Nano-car flame electron excitation Unidirectional Conformational change Moving liner direction STM tip Exciting electron from STM tip (STM-IETS)

Electric nanocar Rotor unit conversion previous research Nature 2005,437, 1337-1340

Molecule movement along a surface STM at 7K 1step – scanning(<60mV,<50 pA) =>No scanning (600mV, 30 - 50 pA) On a Cu(111) surface

Double bound isomerization Electron excitation the electron could excite a phonon or molecules vibrational mode with an energy quantum of ħω Check threshold ħω/e(mV) e⊿V≧ħω(molecule vibration energy) => Electron induce molecule conversion Movement components Double bound isomerization Helix inversion http://www.ucl.ac.uk/chemistry/research/group_pages/nano/facilities/spectroscopy

Helix inversion

Double bond isomerization+Helix invesion Each data point represents 8 to40 manipulations performed on various molecules (I=30–50 pA)

Polarity dependence of Helix invesion Negative bias -> no movement Positive voltage pulses -> leading to movement and helix inversion.

Electron excitation ħω~500meV e⊿V≧ħω(molecule vibration energy) Double bound isomerization ħω~500meV e⊿V≧ħω(molecule vibration energy) Electron induce molecule conversion (one electron cause one reaction) Difference between The presence LUMO and fermi level Helix inversion ħω~200meV C=C bound starching vibration

STM-image each isomer

Movement control by chirality of isomer

Conclusion Scanning tunnelling microscopy confirms that activation of the conformational changes of the rotors through inelastic electron tunnelling propels the molecule unidirectionally across a Cu(111) surface. The system can be adapted to follow either linear or random surface trajectories or to remain stationary, by tuning the chirality of the individual motor units. their design provides a starting point for the exploration of more sophisticated molecular mechanical systems with directionally controlled motion.

Synthetic scheme 1 (rotor unit)

Synthetic scheme 2 (making nano-car flame)

表面科学Vol. 24, No. 5, pp. 313―317, 2003

表面科学Vol. 24, No. 5, pp. 313―317, 2003

A tunneling electron emitted from a STM tip is trapped in a molecule-induced resonant state.  The electron is dissipated into the metal surface after a short time, during which the electron could excite a phonon or molecules vibrational mode with an energy quantum of ħω