On the Analysis of Some Orbital Contributions to the Current Density in Circulenes

According to the ipsocentric method, the current density stems from a sum of rotationally and translationally allowed transitions: translationally allowed transition are diatropic and rotationally allowed transition must be prevailingly paratropic. Applying this method to circulenes, we show that it can be used, together with simple Huckel theory, to design systems with localized currents on the rim. More importantly, we report the current density maps of coronene(2+) and coronene(2-). In these systems, a single rotational contribution gives both diatropic and paratropic circulations. This finding has been interpreted by a simple model based on the orbitals of the subsystem, which are the hub and the rim. It turns out that, in such cases, simple inspection of the Huckel orbitals is Sufficient to predict the relative tropicities on the rim and the hub. (C) 2008 Wiley Periodicals, Inc. Int Quantum Chem 109: 243-249, 2009