Depending on the twist, scientists define chiral objects as left-handed and right-handed. Objects that can superimpose themselves on their mirror image, such as a wine goblet, are not chiral.
In optics, chiral molecules rotate the polarization of light the direction depends on whether the molecules are left-handed or right-handed. Liquid crystal computer and television screen manufacturers take advantage of this property to enable you to clearly see images from an angle.
In the drug industry, chirality is crucial.
Two drugs with the identical chemical formula have different uses. Dextromethorphan, which is right-handed, is a cough syrup and levomethorphan, which is lefthanded, is a narcotic painkiller.
The reason for the different effects? The drugs interact differently with biomolecules inside us, depending on the biomolecules' chirality.
After meeting with Lemieux at a conference, the researchers invented a method to create chirality in a liquid crystal at the molecular level.
They treated two glass slides so that cigar-shaped liquid crystal molecules would align along a particular direction. They then created a thin cell with the slides, but rotated the two alignment directions by approximately a 20 degree angle.
The 20-degree difference caused the molecules' orientation to undergo a right-handed helical rotation, like a standard screw, from one side to the other. This is the imposed chiral twist.
The twist, however, is like a tightened spring and costs energy to maintain. To reduce this cost, some of the naturally left-handed molecules in the crystal became right-handed. That's because, inherently, right-handed molecules give rise to a macroscopic right-handed twist, Rosenblatt explained. This shift of molecules from left-handed to right-handed is the induced chirality.
Although the law of entropy suggests there would be nearly identical numbers of left-handed and right-
|Contact: Kevin Mayhood|
Case Western Reserve University