A DFT study on disubstituted R-hexahelicenes having donor/acceptor groups

In order to investigate the positional effects of both–NH2 and–NO2 groups over the quantum chemical properties of hexahelicene, sixteen different types of terminal donor/acceptor (–NH2/–NO2) disubstituted R–hexahelicenes (Hn, n=1–16) have been designed and theoretically investigated by DFT method at B3LYP/6–31G(d) level. The electronic and thermodynamical properties and molecular orbitals of hexahelicene and all Hn compounds have been discussed. NICS(0) calculations have been performed for all the rings of hexahelicene and Hn structures to inspect the aromaticities. It was observed that generally the position of–NO2 (acceptor) was more effective over the quantum chemical properties of Hn structures than the position of–NH2 (donor). However,–NH2 substitution at C5 carbon (in H4, H8, H12 and H16 compounds) increases the aromaticities of terminal rings in a significant manner