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 et al., Mon Chem, 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 π-electron energy of the two-ring-deleted conjugated fragment. eng All rights reserved Indian Journal of Chemistry vol. 48 br. 12 str. 1657-1661 application/pdf 212737 bytes https://phaidrabg.bg.ac.rs/o:34074 ISSN: 0376-4710 2009 Radenković, Slavko Linert, Wolfgang Gutman, Ivan Jeremić, Svetlana info:eu-repo/semantics/article Pairwise energy effects of rings in benzo-annelated perylenes Keywords: Theoretical chemistry, Graph theory, Cyclic conjugation, Pairwise energy, Perylenes, Benzo-annelated perylenes