Some of this year, the development of nano-technology, very fast. This technology is predicted by futurists Alvin and Heidi Toffler in a paper as the "50 Year Future Technology". This fact is further reinforced by the attitude of the developed countries which give more attention to nanotechnology. One of them is the research Fullerene (C60), a compound with a unique shape like a ball of radius 0.7 nanometer (1 nanometer equals one billion meters). Fullerene-forming elements consisting entirely of carbon. At first it was not recognized by the chemists of carbon because the crystal structure of carbon compounds in nature only diamond and graphite. While others are in the form of amorphous, meaning no crystal shape or not.
Fullerene has physical properties very stable and strong, even though virtually destroyed tossed with rocket speed. But he easily chemically react because many have covalent bonds across the surface. This characteristic is very different from the two previous generations of the carbon crystal diamond and graphite, thus opening a broad application opportunities, among others in the field of electronics, chemistry and medicine.
Figure 1. Structure buckminsterfullerene, C60
Figure 2. The FCC in the form of Fullerene
Figure 3. C60 derivatives which are ferromagnet (source Nature 1992, 355, p331)
The discovery of Fullerene
Fullerene was found by accident by Harold W. Kroto, one a professor at Sussex University, England. Kroto spektroskopis actually a microwave that investigated the relationship of carbon chains in interstellar space. Between 1975-1978 he managed to detect a variety of carbon chains such as HC5N, HC7N and HC9N. Kroto assume that the carbon chain is derived from the explosion when a new star is formed.
When visiting laboratories Richard Smalley at Rice University in Houston in 1984, Kroto get a unique instrument, called "Laser vaporization cluster beam apparatus" Smalley group used to synthesize the cluster, which is a collection of approximately 100 pieces silicon and germanium atoms. Kroto Smalley convinced that this tool can be used to simulate the explosion that occurred during the birth of stars in space that will produce carbon compounds like he was thinking. They practice the simulation was in September 1985, but did not get the carbon chain as predicted. As it is known only to the amount of C60 compounds more than other compounds.
Form of Fullerene as they are now known only realized after seeing the geodesic dome-shaped ball by R. Buckminster Fuller. But unfortunately there was no valid data really showed that ball-shaped C60, although the experts when it had begun to recognize C60 is a stable compound.
Fullerene proving successful form a new ball made in 1990, when a joint team of American and German Kratschmer and Huffman, managed to produce large amounts of Fullerene, although actually only a few milligrams of it. The way in which simple, namely by heating and evaporation of carbon rods in vacuum tubes. This is called the thermal resistance method. Carbon will stick to the inside of the tube containing C60 to 10%. After the measurements were taken which proved that spektroskopis Fullerene spherical. Buckminster Fullerene name used to commemorate the architect geodesic dome, while the other name is Bucky ball. Kroto and his own group to get nobel prize in Chemistry in 1996.
Kroto actually not the first to predict the form of Fullerene ball. Year 1970 Eiji Ohsawa, a professor at Toyohashi University, was simulating that C60 is a spherical carbon compounds are stable. It started when he synthesize Corannulene (C20H20) is a third ball-shaped compound. But unfortunately Ohsawa scientific papers written in Japanese so there was no repercussions in Europe.
Fullerene Applications
Smalley group to develop "Metal Inclusion", which is a metal insert into the Fullerene. This assumption dillakukan, if Fullerene necessarily spherical empty space inside that can be inserted metal. Although this can not be used as evidence that the form of Fullerene ball, but from the experiment results show that the metal can be incorporated into Fullerene by placing the graphite which is coated on the metal cluster of laser equipment.
The interesting thing about this research is to make Fullerene has a charge. Fullerene will get electrons from the metal in it, so that the metal is positively charged, while himself into fullerenenya negatively charged. Thus was obtained the results seemed like a giant atom in which the positively charged and negatively charged on the outside. Giant atom is then called super atoms. In the future if this technology was developed further, could the contents of Fullerene with radioactive metals remaining nuclear fuel. Moreover, it can also be used for the treatment of cancer with radioactive metal insert and place it on the local radioactive cancer alone.
That is not less interesting is to make polymers fullerane which is expected to have magnetic properties. The assumption is based on the structures that form the structure fullerane face centered cubic (fcc). In temperature and high voltage (6GPa, 1025-1050K) along with the changing tilt Fullerene structure will be formed covalent bond that results in polymers with a structure similar to graphite. On top of that form covalent bonds that will be rotating electrons cause magnetic properties. These magnetic properties can be utilized in the world of electronics, for example a computer memory, magnetic sensors or medicine.
In nanoelektronik Fullerene has the advantage of superconducting properties owned. As we know superconductor is a material that has no barriers or resistance below a certain temperature value. He could just be a conductor, semiconductor or insulator at room temperature. The temperature where the conductivity properties change becomes superconducting is called the critical temperature (Tc).
Basically, in the form of Fullerene crystals are insulators, but when in-doping with alkali metal A3C60 (A = K, Rb) Fullerene changed the nature of the superconductor. K3C60 as having a critical temperature of 15K, while the average of the Fullerene-doped with alkali metal has a critical temperature of 30K. Although still far compared to ceramic superconductors which have an average critical temperature 90K, but Fullerene is promising as a future superconducting materials. Moreover, in 2000, Lucent Technology Co.. Ltd. managed to find the superconducting properties of single crystal Fullerene 52K at a critical temperature, which when in-doping with tribromometan (CHBr3) successfully demonstrated superconducting properties at temperatures 117K. These results are close to the highest critical temperature is currently owned by Hg0.8Tl0.2Ba2Ca2Cu3O8.33 at 138K temperature.
Although not applied directly, in character as a superconductor will be used widely in the field of electronics. Efficiency reaches 99% caused very little electricity is wasted into heat. This capability can be used as an electric transmission to replace copper wire transmission underground is being planned as Japan and America.
In medicine, the nature of stable and non-toxicnya Fullerene can be used as a drug, one of whom is HIV antiviral drugs. "Ball" Fullerene with its lipophilic nature (easily integrated in fat or oil) will easily fit into the protease structure on which the HIV virus reproduction. Thus he could keep the growth rate of the HIV virus. This method actually fear it would get the same results when using other anti-HIV drugs that have failed due to changes in the form of the virus changing. But with a round shape like a ball, the surface of Fullerene can be modified with a variety of functions that are expected to restrain the proliferation of the HIV virus. In the near future drug company C Sixty is located in Toronto, Canada will issue these drugs are based on Fullerene.
Thus some current applications to the attention of many experts in their respective fields. There are many other things that have not known of the material that is currently the leading materials. Fullerene research on this will continue to grow, especially with more and more ways are found to produce the 'ball' Fullerene with cheap and easy. According to Chemical Week, Mitsubishi Chemical will suppress Fullerene price of $ 20 per gram (in 2000) to 0.2 $ per gram in 2004. This price would make the researchers more eager to find other new things from Fullerene.
Edi Sukur
Post Doctoral Fellow at the Tonen General Sekiyu KK, Japan
Reference
H.-B.Burgi, E. Blanc, D. Schwarzenbach, Shengzhong Liu, Ying-jie Lu, MMKappes, JAIbers, Angew.Chem., Int.Ed.Engl., 31, p640, 1992 (FCC).
PWStephens, D. Cox, JWLauher, L. Mihaly, JBWile, P.-M.Allemand, A. Hirsch, K. Holczer, Q. Li, JDThompson, F. Wudl, Nature (London), 355, p331, 1992 (magnet).
Tidak ada komentar:
Posting Komentar