Explore: Asymmetrie

Atropisomers are a kind of stereoisomer arising because of hindered rotation about a single bond, where energy differences due to steric strain or other contributors create a barrier to rotation that is high enough to allow for isolation of individual rotamers They occur naturally and are of occasional importance in pharmaceutical design. When the substituents are achiral, these conformers are enantiomers (atropoenantiomers), showing axial chirality; otherwise they are diastereomers (atropodiastereomers).

Cluster decay, also known as heavy particle radioactivity, is a rare type of radioactive decay in which an unstable atomic nucleus emits a small cluster of protons and neutrons. The emitted cluster is larger than an alpha particle (which has two protons and two neutrons) but smaller than the typical fragments produced in spontaneous fission. This process is a way for a heavy, unstable atom to become more stable. For example, an atom of 22388Ra can emit a 146C nucleus (which contains 6 protons and 8 neutrons) and transform into a more stable 20982Pb atom. Cluster decay was theoretically predicted in 1980 by Aureliu Săndulescu, Dorin N. Poenaru, and Walter Greiner, and was first experimentally confirmed in 1984 by H. J. Rose and G. A. Jones.