Their work could aid the development of enantiomeric drugs and advanced materials. Flipping a coin many times naturally tends toward a 50–50 ratio of heads and tails. But flipping a coin once results in a single outcome, either a head or a tail. Zheng and Long reasoned that they could apply these statistical principles to chemically control homochiral crystallization without the aid of a chiral catalyst, template, or chiral starting materials. "By chemically manipulating the statistical fluctuation in crystallization, the otherwise equal probability of attaining the left- or right-handed isomers of a helical coordination polymer is significantly skewed, and in an ideal case, only one enantiomeric form is produced," Zheng says. The researchers demonstrated the phenomenon by synthesizing a three dimensional network polymer consisting of helical chains of copper succinate bridged by 4,4′-bipyridine groups.
by Stephen K. Ritter |
October 29, 2007