Issue Date: May 7, 2007
Molecules' Open Arms Influence Nanoshapes
A nanoparticle's shape and size can influence its properties just as much as its chemistry, so the ability to predict the former from the latter would be a boon to nanoscientists. Now, a research team at the Chinese Academy of Sciences, in Beijing, has taken a step closer to doing just that for nanoparticles made from substituted benzenes (Chem. Commun. 2007, 1623). Hongbing Fu, Jiannian Yao, and coworkers prepared ortho, meta, and para isomers of bis(iminopyrrole)benzene and then observed the formation of nanospheres, nanowires, and nanocubes, respectively. Fu and Yao explain that intermolecular hydrogen bonding between the iminopyrrole arms hanging from the benzene ring of the isomers plays a critical role in determining which nanoparticle shape eventually forms. The ortho isomer, with its arms held at a 60° angle from one another, likely dimerizes before aggregating into spheres, they note. The extended arms of the meta and para isomers, they reason, are more likely to join up to form longer chains. The 120° m-bis(iminopyrrole)benzene chains take on a zigzag shape and end up as nanowires, whereas the 180° p-bis(iminopyrrole)benzene chains don't mesh together as well and form truncated cubes.
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