Molecules with Linearπ-Conjugated Pathways between All Substituents: Omniconjugation

In this paper, omniconjugation is introduced as a topological phenomenon in π-conjugated systems. Omniconjugated molecules are defined by the fact that they provide direct and fully π-conjugated pathways between all substituents attached to them. Surprisingly, until now such topologies have never been explicitly recognized or investigated from this point of view. A topological design scheme is presented as a tool, which enables for the systematic construction of this novel class of π-electron molecular structures. Molecular building blocks with three or more connection points to the external moieties are proposed, which for the first time allows for the interconnection of many functional entities in a fully conjugated manner. In being truly conjugated, these pathways are expected to provide high transmission probabilities for holes and/or electrons. Omniconjugated structures may play an important role in the design of complex electronic circuitry based on organic molecules. On a larger scale, they may also give rise to special material properties. Although omniconjugation is based on a valence-bond description of the system, it is shown that our concept is in good agreement with results obtained from a molecular-orbital description of the electron probability distribution in the frontier orbitals.