The last post addressed the concept of “steric clashes” in a pericyclic reaction transition state as an extension of the time honoured practice of building molecular models to analyse reaction outcomes. A modern computer generated model might express this in terms of a NCI (non-covalent-interaction) surface.
The first representative of a possible new class of conjugated cyclic polyacetylenes is predicted using DFT calculations. These species have a helical secondary structure and a closed-shell electronic ground-state configuration. Molecular and spectroscopic properties are discussed, and a distinct anapolar ring current structure in a constant and homogeneous magnetic field, perpendicular to the main molecular plane is demonstrated.