My husband works in what I consider to be the materials side of chemistry (he is currently the only chemist in a group of physicists), so even though I am an organic chemist at heart, I really enjoy reading about new developments in nanotechnology. Yesterday I came across a paper entitled "Conductive One-Handed Nanocoils by Coassembly of Hexabenzocoronenes..." and I actually thought it was pretty interesting. Coiled nanofibers have been made previously, but little is known about their conducting properties. This is mostly due to the fact that coiled assemblies of aromatic molecules are not overwhelmingly stable. If one could create coiled, single-handed, electroconductive nanostructures that were also stable, it would be possible to create tiny little electromagnets. Cool, huh?Hexabenzocoronene (HBC) with alkyl and triethylene glycol substituents can self assemble into nanotubes; appending norbornene groups at the end of the triethylene glycol chains leads to the formation of both right- and left-handed helical nanocoils upon self assembly (1). While these nanocoils can be stabilized by subsequent ring-opening methathesis polymerization (ROMP) of the norbornene groups, they are actually only the kinetic product of self assembly. Without the ROMP stabilization, they are eventually converted into the more thermodynamically stable nanotubes. This all seems fascinating enough, but members of the Aida lab were able to take things a step further using what they call the "sergeant and soldier effect" to control the formation of left- or right-handed nanocoils. Doping the original HBC/norbornene construct (1) with as little as 20% of HBC with a shortened linker containing a chiral handle (either R or S) produced single-handed coils (S enantiomer --> left-handed coils, R-enantiomer --> right-handed coils). After doping with I2, the coils are also conductive. It only takes a few sergeants to control an army!
