N-1- and N-2-Anthryl Succinimide Derivatives: C–N Bond Rotational Behaviors and Fluorescence Energy Transfer

New rigid bicyclic N-anthrylsuccinimide 1a, 1b, 2a, and 2b were prepared. The Caryl–Nimide bond rotational barriers, intra/intermolecular arene–arene interactions, and photophysical properties were investigated. The rotational behaviors are more significantly controlled by the position of Caryl–Nimide connection than the sidewall framework. The fluorescence energy transfer (ΦET) in 1a and 1b was estimated to be 61% and 53%, respectively. The difference is attributed to the position of Caryl–Nimide connection, which directly influences the relative orientation of donor (naphthalene) and acceptor (anthracene).