Three contra-rotating currents from a rational design of polycyclic aromatic hydrocarbons: altan-corannulene and altan-coronene.

Both the ab initio expression of the current density within the ipsocentric approach and conjugated circuit models indicate that placing an unsaturated hydrocarbon inside a [4n]annulene, in such a way that outgoing C-H bonds are substituted by C-C bonds to alternating carbon atoms of the annulene, leads to an homologue altan-molecule whose perimeter is expected to preserve the paratropic circulation of the parent annulene. Computations of current on the novel altan-corannulene and altan-coronene revealed unprecedented patterns of three contra-rotating paratropic/diatropic/paratropic circulations. Graph-theoretical methods have been used to highlight the peculiar topology of these altan-molecules.