Route to cycloparaphenylenes could lead to a new way to make carbon nanotubes.
A NOVEL REACTION that could be generally useful for aromatic synthesis has made possible the assembly of a long-sought family of compounds: the cycloparaphenylenes, which are strings of benzenes joined in a ring-around-the-rosy style. The compounds could prove useful for constructing carbon nanotubes, which hold promise for electronics, advanced biosensors, and other applications.
FUNDAMENTAL UNIT
Cycloparaphenylenes (a), made by Bertozzi and coworkers in 9-, 12-, and 18-benzene-ring sizes, are basic building blocks (highlighted bonds) of armchair carbon nanotubes (b).
(a) Cycloparaphenylenes (b)Armchair carbon nanotubes
Synthesis
"It's a landmark synthesis" because of its brevity, elegance, creativity, and high product yields, comments Graham J. Bodwell of Memorial University of Newfoundland, in St. John's, who specializes in conjugated "belt" compound synthesis.
Ramesh Jasti, chemistry professor and Howard Hughes Medical Institute investigator Carolyn R. Bertozzi, and coworkers at Lawrence Berkeley National Laboratory's Molecular Foundry and the University of California, Berkeley, carried out the new synthesis. They succeeded by creating rings of benzenes and cyclohexadienes and then using a new aromatization reaction they developed to convert the cyclohexadienes to benzenes.
The aromatization reaction works under low-temperature conditions and generates high yields of pure products; it is an important achievement in itself. Previously, aromatizations of highly strained compounds led to undesirable rearrangements or formation of complex mixtures.
[Source: ACS]
A NOVEL REACTION that could be generally useful for aromatic synthesis has made possible the assembly of a long-sought family of compounds: the cycloparaphenylenes, which are strings of benzenes joined in a ring-around-the-rosy style. The compounds could prove useful for constructing carbon nanotubes, which hold promise for electronics, advanced biosensors, and other applications.
FUNDAMENTAL UNIT
Cycloparaphenylenes (a), made by Bertozzi and coworkers in 9-, 12-, and 18-benzene-ring sizes, are basic building blocks (highlighted bonds) of armchair carbon nanotubes (b).
(a) Cycloparaphenylenes (b)Armchair carbon nanotubes
Synthesis
"It's a landmark synthesis" because of its brevity, elegance, creativity, and high product yields, comments Graham J. Bodwell of Memorial University of Newfoundland, in St. John's, who specializes in conjugated "belt" compound synthesis.
Ramesh Jasti, chemistry professor and Howard Hughes Medical Institute investigator Carolyn R. Bertozzi, and coworkers at Lawrence Berkeley National Laboratory's Molecular Foundry and the University of California, Berkeley, carried out the new synthesis. They succeeded by creating rings of benzenes and cyclohexadienes and then using a new aromatization reaction they developed to convert the cyclohexadienes to benzenes.
The aromatization reaction works under low-temperature conditions and generates high yields of pure products; it is an important achievement in itself. Previously, aromatizations of highly strained compounds led to undesirable rearrangements or formation of complex mixtures.
[Source: ACS]
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