Molecules: You'd better learn to live with them.
After this weekend's discussion of chirality in advertising, I figured I'd post an interesting, more rigorous example of chirality. Most chiral (left- or right-handed)molecules have "asymmetric" carbons, or ones with all different things attached.
Helicene, by contrast, has none. However, it's got a twist that imparts chirality to it. Think of a left- and right-handed staircase. This, in itself, constitutes chirality - for example, DNA (almost always) twists right. If you put left-handed DNA in ads for your biotechnology company, scientists will make fun of you.
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Check out the thiophene version...
Carbon-Sulfur [n]Helicenes
Posted by: SR | January 29, 2008 11:41 PM
I was just over at drugs and poisons...
www.drugsandpoisons.com/
where there is an interesting post on the chirality of penicillamine, a metabolite of penicillin that is used as a chelating agent. The L-isomer is apparently toxic.
Posted by: kirsten | January 30, 2008 12:12 PM
http://www.mazepath.com/uncleal/17heli.png
The immense optical rotation of nonahelicene is a typo.
Posted by: Uncle Al | January 31, 2008 3:46 PM