Cyclic Organic Nanostructures

Chemists from Caltech and University of California, Berkeley recently reported a direct, Ru-based catalytic procedure for synthesizing organic nanorings. Traditional methods for producing cyclic polymers involved connecting the reactive ends of a linear polymer. This presents problems because dimers and trimers are often formed instead of rings.

The new method is a ring-expansion metathesis polymerization, catalyzed by Ru-carbene catalysts to produce toroidal structures from dendrimers. The rings are produced in reasonable quantities and were studied with atomic force microscopy. The outside diameters range from 35 to 40 nm and the inner diameters from 5 to 7 nm.

According to C. Grant Wilson of the University of Texas, the rings reveal "the ability of chemists to control not only the sequence connectivity of atoms in molecules, but the way in which the resulting molecules form themselves into three-dimensional shapes."


Sources:
C&EN http://pubs.acs.org/isubscribe/journals/cen/87/i16/html/8716notw7.html
JACS http://pubs.acs.org/doi/abs/10.1021/ja901658c