Molecules that are twisted are ubiquitous in nature, and have important consequences in biology, chemistry, physics and medicine. Some molecules have unique and technologically useful optical properties; the medicinal properties of drugs depend on the direction of the twist; and within
Molecules that are twisted are ubiquitous in nature, and have important consequences in biology, chemistry, physics and medicine. Some molecules have unique and technologically useful optical properties; the medicinal properties of drugs depend on the direction of the twist; and within us think of the double helix twisted DNA can interact with different proteins.
This twisting is called chirality and researchers at Case Western Reserve University have found they can use a macroscopic brute force to impose and induce a twist in an otherwise non-chiral molecule.
Their new "top-down" approach is described in the Dec. 2 issue of Physical Review Letters.
"The key is that we used a macroscopic force to create chirality down to the molecular level," said Charles Rosenblatt, professor of physics at Case Western Reserve and the senior author on the paper. Rosenblatt started the research with no application in mind. He simply wanted to see if it could be done essentially scientific acrobatics.
But, he points out, since antiquity chirality has played a role in health, energy, technology and more but until now, chirality always has been a bottom-up phenomenon. This new top-down approach, if it can be scaled up, could lead to custom designed chirality - and therefore desired properties - in all kinds of things.
Rosenblatt worked with post-doctoral researcher Rajratan Basu, graduate student Joel S. Pendery, and professor Rolfe G. Petschek, of the physics department at Case Western Reserve, and Chemistry Professor Robert P. Lemieux of Queen's University, Kingston, Ontario.
Chirality isn't as simple as a twist in a material. More precisely, a chiral object can't be superimposed on its mirror image. In a "thought experiment", if one's hand can pass through a mirror (like Alice Through the Looking Glass), the hand cannot be rotated so that it matches its mirror image. Therefore one's hand is chiral.
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 scre