Influence of structural isomers of naphthalene diimides on photophysical and electrochemical properties

Three structural isomers of naphthalene diimides were synthesized. In all compounds, the electron-withdrawing diimide group exhibits a stable two-step reduction behavior under electrochemical conditions, and it was revealed that their reduction potentials vary significantly depending on the position of the diimide group relative to the naphthalene ring. The structural isomers of naphthalene diimides, 1,4,5,8-NDI and 2,3,6,7-NDI, and 1,2,5,6-NDI derivatives were synthesized, and all of them were found to exhibit a reversible 2-electron reduction behavior. Depending on the modification position of the diimide relative to the naphthalene ring, it was found that 1,4,5,8-NDI, 1,2,5,6-NDI, and 2,3,6,7-NDI required larger reduction potentials, in that order.