Chemical Fullerene-A New Form of Carbon Connectios A favorite chemisury examination question is:What are ists refer to it as Cea or fullerene;some call it"bucky- the elemental forms of carbon?For a long time,the an- ball."Kroto,Smalley,and Robert F.Curl were awarded swer was that pure carbon is found in two forms:graph- the 1996 Nobel prize in chemistry for this work.Some ite and diamond.These forms have been known for other fullerenes,such as C and Cst have now been iso centuries,and it was generally believed that they are the lated and studied as well. only forms of carbon having extended nerworks of C at- Fullerenes have a rich chemistry.They behave as if oms in well-defined structures.But that is not so!The they have clectron-deficient double bonds.Many differ- scientific world was started in 1985 when Richard Smal ent fullerene adducts with a variery of srucures have ley of Rice University and Harry W.Kroto of the Univer been prepared.Cationic derivatives of these adducts, sity of Sussex,UK,and their coworkers announced that for example,bind tightly to DNA and can be used to they had detected a new form of carbon with the mo visualize it by electron microscopy. lecular formula Ca.They suggested that the molecule An important development in this field has been the has a structure that resembles a soccer ball;it has 1?five preparation of single-wall nanotubes,which are based on membered rings and 20 six-membered rings arranged Co or higher fullerenes and are extended for a very long such that each five-membered ring is surrounded by 5 distance to make long molecules that are hundreds of six-membered rings.This structure reminded its dis times stronger than stcel and can act as molecular wires coverers of a geodesic dome,a stnicture invented by Nanotubes can be used as the probe (a very sharp tip) the innovative American engineer and philosopher R in atomic force microscopes,which can be used to im Buckminster Fuller.Therefore,the official name of this age single molecules.The nanotubes make the sharpes allotrope of carbon has become fullerene.Most chem- possible tips because they are of molecular dimensions. Nanotubes are also playing an increasingly important role in the field of nanotechnology,including applica tions in the area of molecular electronics.Nanotubes can be superconducting or semiconducting.depending on the exact structure of the nanotube. A fullerrne (Go)moierule. A nanotube