Frontier Orbital Perspective for Quantum Interference in Alternant and Nonalternant Hydrocarbons

The wave-particle duality of electrons gives rise to quantum interference (QI) in single molecular devices. A significant challenge to be addressed in molecular electronics is to further develop chemical intuition to understand and predict QI features. In this study, an orbital rule is markedly ameliorated so that it can capture the manifestation of QI not only in alternant hydrocarbons but also in nonalternant ones. The orbital-based prediction about the occurrence of QI in a nonalternant hydrocarbon shows good agreement with experimental results. A simple perturbation theoretic line of reasoning suggests that frontier orbital phase and splitting play a pivotal role in QI phenomena.