Same or Different? How a Simple Carbon Atom Leads to Complex Natural Compounds

A deceptively simple atom like carbon exhibits diverse styles of bonding that can lead to a plethora of complex organic molecules:

Carbon's flexibility in bonding makes it possible for molecules to have structural complexity, such as nonsuperimposable mirror images known as enantiomers:

In this example, these are not the same molecule even though the way the individual atoms are connected is the same. Because the 3-dimensional spatial arrangement around the central carbon atom is different, these are also known as chiral molecules or enantiomers, and carbon is called a chiral center.

There is a nice video created by Lydia Flynn where she demonstrates how molecules can be chiral using molecular models.

Chirality/Basic Concept Explained

Chiral molecules can be found in nature, and sometimes we need an extra few seconds to check if we are seeing the same molecule or two different molecules. One example is a compound produced female gypsy moths known as disparlure. It turns out that only one form of this molecule (in purple) is attractive to male moths.

 

Female Gypsy Moth

"Lymantria dispar 8-8-2006 19-20-14" by Opuntia. 

Licensed under CC BY-SA 3.0 via Wikimedia Commons

Molecular models show these are enantiomers and not the same molecule of disparlure.

Brown tube sponge from the National Museum of Natural History (image by Rachel Cooper)

Sceptrin is a compound made by the brown tube sponge. It is currently researched for its antibiotic potential.

 

These are enantiomers of sceptrin, a compound whose structure was first synthesized in 2004 by scientists in The Scripps Research Institute.

Molecular models again illustrate the nonsuperimposability of these mirror image isomers.