Stereoisomers are molecules that have all the same atoms connected in the same way but arranged differently in space. Conformational isomers, or conformers, are stereoisomers that can readily interconvert at room temperature and are typically considered versions of the same molecule. An understanding of conformers is particularly important in the study of biological systems, since a biomolecule’s function is so often related to its physical shape. Protein folding, for example, involves the interconversion of conformers. But it’s difficult to study conformers individually because any room-temperature sample necessarily contains a mix of them, and they respond identically to the usual separation techniques, such as mass spectrometry.
Now, Jochen Küpper, his student Frank Filsinger, and colleagues at the Fritz Haber Institute in Berlin, Germany, have developed a way to spatially separate conformers in a molecular beam. 1 They looked at the cis and trans conformers of the molecule 3-aminophenol, shown in the...
