Investigating the motion of molecular machines on surfaces by STM: The nanocar and beyond

Abstract

To build up true molecular machines and understand the mechanics of nanoscale motion and manipulation in molecular system, we have created and investigated a family of molecules based around the concept of the nanocar, which has the rolling wheels made of spherical fullerene or carborane molecules. Assisted by scanning tunneling microscopy (STM), we have successfully characterized and manipulated these molecules. In addition, we have observed the behavior of these systems when thermal energy is applied. These initial studies open a new realm of nano-sized mechanical, chemical, and electrical devices.

Influence of Vacancies and Grain Boundaries on the Diffusive Motion of Surface Rolling Molecules

“…Consequently, a few experimental studies of nanocars have been accomplished. Zhang et al 20 reported one of the most valuable experimental observations and examined the motion of a few types of surface rolling molecules, including the nanocar. They reported that the nanocar remains almost motionless on the flat gold surface at temperatures lower than 200 °C, and it starts to move on the surface at the temperature of 200 °C.…”

“…A specially developed scanning tunneling microscopy (STM) machine imaged the whole race. 14,18 Shirai et al 19 and Zhang et al 20 conducted experimental tests on first-generation nanocars in UHV conditions to investigate the motion of nanocars on a gold substrate. Claytor et al 21 studied the motion of some p-carborane wheeled nanocars on a metallic substrate.…”

“…Experimental investigation of nanocar motion is not only costly and time-consuming but also unable to reveal the detailed motion of the wheels, deformation of the chassis, and many other phenomena that happen on the nanosecond time scale. 20,23 Utilizing nanocars in real-world applications is possible only when we have a clear and detailed knowledge of their behavior in different conditions and situations. Therefore, computational simulations are necessary and practical to fill these gaps and to obtain a better understanding of nanocar motion.…”

“…Experimental investigation of nanocar motion is not only costly and time-consuming but also unable to reveal the detailed motion of the wheels, deformation of the chassis, and many other phenomena that happen on the nanosecond time scale. , …”

Design of Carborane Molecular Architectures via Electronic Structure Computations

“…We have utilized a bottom-totop approach and electronic structure computations to design icosahedral borane and carborane molecular architectures by starting with single molecules as well as with dimeric units connected directly or through bridges [3][4][5][6][7][8][9][10][11][12][13][14][15][16]. Knowledge of the electronic, magnetic, optical, and other properties of such single and dimeric units illuminates the evaluation of the global properties of 1D, 2D, or 3D superclusters and nanostructures [17][18][19][20][21][22]. The use of light to modify properties of nanostructures is at the heart of current cutting-edge technology.…”