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Aromaticity Forced Out

Principal Investigator: 

What do the human body and the vacuum of interstellar space have in common? Aromatic molecules, of course! The six-membered benzene ring is the beating heart of everyday molecules like aspirin and detergents, tough materials like Kevlar, and amazing graphene, which promises to revolutionize consumer electronics. Much of this ubiquity is thanks to the stability that results when electrons are evenly spread out, or delocalized, above and below the benzene ring. The particularly strong delocalization in benzene and its derivatives is known by chemists as aromaticity. As a major stabilizing force, aromaticity is exploited universally by chemists and in nature to fabricate molecular structures and direct their reactivity. Our recent work has unearthed a different chemical driving force due to the delocalization of partial positive and negative charges on groups attached to a benzene ring. We discovered that the force toward an alternative neutral structure was strong enough to disrupt the normal mode of electron delocalization in benzene mentioned above. In the process, the central ring twists in order to accommodate the bulky groups outside, destroying the planar structure that is regarded as one of the hallmarks of aromatic character. This work was recently published by Hessam Mehr (PhD student in MacLachlan group) in the journal Organic Letters.  Link