Pairwise energy effects of rings in benzo-annelated perylenes

Abstract

DFT calculations have been used to corroborate two regularities resulting from the analysis of cyclic conjugation in benzo-annelated perylenes reported earlier, viz., (a) the annelation of a benzene ring in angular position increases the extent of cyclic conjugation in the central ring, and, (b) the annelation of a benzene ring in linear position decreases the extent of cyclic conjugation in the central ring of benzo-annelated perylenes [Gutman <i>et al</i>.,<i style=""> Mon Chem,</i> 135 (2004) 1389]. In addition, a new method for assessing the pairwise energy effect is used to rationalize the obtained results. In the case of benzo-annelated perylenes, the pairwise energy effect is found to be related to the total <img src='/image/spc_char/pi.gif' border=0>-electron energy of the two-ring-deleted conjugated fragment.