Nanocar
Encyclopedia
The nanocar is a molecule designed in 2005 at Rice University
by a group headed by Professor James Tour
. Despite the name, the original nanocar does not contain a molecular motor
, hence, it is not really a car. Rather, it was designed to answer the question of how fullerene
s move about on metal surfaces; specifically, whether they roll or slide.
The molecule consists of an H-shaped 'chassis' with fullerene
groups attached at the four corners to act as wheels.
When dispersed on a gold
surface, the molecules attach themselves to the surface via their fullerene groups and are detected via scanning tunneling microscopy
. One can deduce their orientation as the frame length is a little shorter than its width.
Upon heating the surface to 200 °C the molecules move forward and back as they roll on their fullerene "wheels". The nanocar is able to roll about because the fullerene wheel is fitted to the alkyne
"axle" through a carbon-carbon single bond. The hydrogen on the neighboring carbon is no great obstacle to free rotation. When the temperature is high enough, the four carbon-carbon bonds rotate and the car rolls about. Occasionally the direction of movement changes as the molecule pivots. The rolling action was confirmed by Professor Kevin Kelly, also at Rice, by pulling the molecule with the tip of the STM
microscope.
. These papers supposed to be a not-so-serious contribution to a fundamental debate on the limits of bottom-up Drexlerian nanotechnology and conceptual limits of how far mechanistic analogies advanced by Eric Drexler could be carried out. The important feature of this nanocar concept was the fact that all molecular component tinkertoys were known and synthetized molecules (alas, some very exotic and only recently discovered, e.g. staffenes, and notably – ferric wheel, 1995), in contrast to some Drexlerian diamondoid structures that were only postulated and never synthesized; and the drive system that was embedded in a ferric wheel and driven by inhomogeneous or time-dependent magnetic field of a substrate – an "engine in a wheel" concept.
wheels and a light powered helicene
synthetic molecular motor. Although the motor moiety displayed unidirectional rotation in solution, light-driven motion on a surface has yet to be observed. Motility in water and other liquids can be also realized by a molecular propeller
in the future.
Rice University
William Marsh Rice University, commonly referred to as Rice University or Rice, is a private research university located on a heavily wooded campus in Houston, Texas, United States...
by a group headed by Professor James Tour
James Tour
James M. Tour is a synthetic organic chemist, specializing in nanotechnology.-Career:He is well-known for his work in molecular electronics and molecular switching molecules. He has also been involved in other work, such as the creation of a nanocar and NanoKids, an interactive learning DVD to...
. Despite the name, the original nanocar does not contain a molecular motor
Synthetic molecular motors
Synthetic molecular motors are molecular machines capable of rotation under energy input. Although the term "molecular motor" has traditionally referred to a naturally occurring protein that induces motion , some groups also use the term when referring to non-biological, non-peptide synthetic...
, hence, it is not really a car. Rather, it was designed to answer the question of how fullerene
Fullerene
A fullerene is any molecule composed entirely of carbon, in the form of a hollow sphere, ellipsoid, or tube. Spherical fullerenes are also called buckyballs, and they resemble the balls used in association football. Cylindrical ones are called carbon nanotubes or buckytubes...
s move about on metal surfaces; specifically, whether they roll or slide.
The molecule consists of an H-shaped 'chassis' with fullerene
Fullerene
A fullerene is any molecule composed entirely of carbon, in the form of a hollow sphere, ellipsoid, or tube. Spherical fullerenes are also called buckyballs, and they resemble the balls used in association football. Cylindrical ones are called carbon nanotubes or buckytubes...
groups attached at the four corners to act as wheels.
When dispersed on a gold
Gold
Gold is a chemical element with the symbol Au and an atomic number of 79. Gold is a dense, soft, shiny, malleable and ductile metal. Pure gold has a bright yellow color and luster traditionally considered attractive, which it maintains without oxidizing in air or water. Chemically, gold is a...
surface, the molecules attach themselves to the surface via their fullerene groups and are detected via scanning tunneling microscopy
Scanning tunneling microscope
A scanning tunneling microscope is an instrument for imaging surfaces at the atomic level. Its development in 1981 earned its inventors, Gerd Binnig and Heinrich Rohrer , the Nobel Prize in Physics in 1986. For an STM, good resolution is considered to be 0.1 nm lateral resolution and...
. One can deduce their orientation as the frame length is a little shorter than its width.
Upon heating the surface to 200 °C the molecules move forward and back as they roll on their fullerene "wheels". The nanocar is able to roll about because the fullerene wheel is fitted to the alkyne
Alkyne
Alkynes are hydrocarbons that have a triple bond between two carbon atoms, with the formula CnH2n-2. Alkynes are traditionally known as acetylenes, although the name acetylene also refers specifically to C2H2, known formally as ethyne using IUPAC nomenclature...
"axle" through a carbon-carbon single bond. The hydrogen on the neighboring carbon is no great obstacle to free rotation. When the temperature is high enough, the four carbon-carbon bonds rotate and the car rolls about. Occasionally the direction of movement changes as the molecule pivots. The rolling action was confirmed by Professor Kevin Kelly, also at Rice, by pulling the molecule with the tip of the STM
Scanning tunneling microscope
A scanning tunneling microscope is an instrument for imaging surfaces at the atomic level. Its development in 1981 earned its inventors, Gerd Binnig and Heinrich Rohrer , the Nobel Prize in Physics in 1986. For an STM, good resolution is considered to be 0.1 nm lateral resolution and...
microscope.
Independent early conceptual contribution
The concept of a nanocar built out of molecular "tinkertoys" was first hypothesized at the Fifth Foresight Conference on Molecular Nanotechnology (November 1997). Subsequently an expanded version was published in Annals of Improbable ResearchAnnals of Improbable Research
The Annals of Improbable Research is a bi-monthly magazine devoted to scientific humor, in the form of a satirical take on the standard academic journal...
. These papers supposed to be a not-so-serious contribution to a fundamental debate on the limits of bottom-up Drexlerian nanotechnology and conceptual limits of how far mechanistic analogies advanced by Eric Drexler could be carried out. The important feature of this nanocar concept was the fact that all molecular component tinkertoys were known and synthetized molecules (alas, some very exotic and only recently discovered, e.g. staffenes, and notably – ferric wheel, 1995), in contrast to some Drexlerian diamondoid structures that were only postulated and never synthesized; and the drive system that was embedded in a ferric wheel and driven by inhomogeneous or time-dependent magnetic field of a substrate – an "engine in a wheel" concept.
Electrically driven directional motion of a four-wheel molecule on a metal surface
Kundernac et al. described a specially designed molecule that has four motorized "wheels". By depositing the molecule on a copper surface and providing them with sufficiently energy from electrons of a scanning tunnelling microscope they were able to drive some of the molecules in a specific direction, much like a car, being the first single molecule capable to continue moving in the same direction across a surface. Inelastic electron tunnelling induces conformational changes in the rotors and propels the molecule across a copper surface. By changing the direction of the rotary motion of individual motor units, the self-propelling molecular 'four-wheeler' structure can follow random or preferentially linear trajectories. This design provides a starting point for the exploration of more sophisticated molecular mechanical systems, perhaps with complete control over their direction of motion.Motor Nanocar
A future nanocar with a synthetic molecular motor has been developed by Jean-Francois Morin et al. It is fitted with carboraneCarborane
A carborane is a cluster composed of boron and carbon atoms. Like many of the related boranes, these clusters are polyhedra and are similarly classified as closo-, nido-, arachno-, hypho-, etc...
wheels and a light powered helicene
Helicene
Helicenes in organic chemistry are ortho-condensed polycyclic aromatic compounds in which benzene rings or other aromatics are angularly annulated to give helically-shaped molecules...
synthetic molecular motor. Although the motor moiety displayed unidirectional rotation in solution, light-driven motion on a surface has yet to be observed. Motility in water and other liquids can be also realized by a molecular propeller
Molecular propeller
Molecular propeller is a molecule that can propel fluids when rotated, due to its special shape that is designed in analogy to macroscopic propellers : it has several molecular-scale blades attached at a certain pitch angle around the circumference of a shaft, aligned along the rotational...
in the future.
See also
- Molecular motor
- Molecular propellerMolecular propellerMolecular propeller is a molecule that can propel fluids when rotated, due to its special shape that is designed in analogy to macroscopic propellers : it has several molecular-scale blades attached at a certain pitch angle around the circumference of a shaft, aligned along the rotational...
- NanoputianNanoputianNanoputians are a series of organic molecules whose structural formulae appear human. James Tour et al. designed and synthesized these compounds in 2003 as a part of a sequence of chemical education for young students...
- NanodragsterNanodragsterThe Nanodragster, dubbed the world's smallest hot rod, is a molecular nanocar. The design improves on previous nanocar designs and is a step towards creating molecular machines...
- Synthetic molecular motorsSynthetic molecular motorsSynthetic molecular motors are molecular machines capable of rotation under energy input. Although the term "molecular motor" has traditionally referred to a naturally occurring protein that induces motion , some groups also use the term when referring to non-biological, non-peptide synthetic...
External links
- Rice University press release
- A New Model Nanocar on the Showroom Floor – Article covering the development of the second generation nanocar at Rice University including an interview with Professor Kevin F. Kelly.
- Click here to drive the Nanocar online – You can drive a NanoCar in the free NanoQuest Serious Game project