Chirality Assisted Triplet Electron Pairing

Abstract

Redox processes that involve pairs of electrons are common in nature. Some of these reactions involve oxygen molecules. The understanding of the efficiency of the oxygen reduction reaction (ORR), for example, is a challenge since the reaction is spin forbidden and requires the transfer of two pairs of electrons. Past experimental and theoretical studies demonstrated that by controlling the spin of the transferred electrons, it is possible to overcome the barrier resulting from the spin mismatch between the reactants and the products. In other works, it was suggested that the reaction is enhanced if the two electrons in each pair have phase relation, namely, they possess the property of a triplet state. Since in nature electrons are transferred through chiral systems, we probed if chirality affects the formation of paired electrons with the same spin, namely, a triplet like state. The model calculations demonstrate that chirality enhances the probability of the formation of electron pairing in the triplet states, even at room temperature. This enhancement originates from breaking the spin degeneracy, enabled by chirality and interaction of the spins with vibrations.