Stringing the Perylene Diimide Bow
Taifeng Liu, Jingjing Yang, Florian Geyer, Felisa Conrad-Burton, Raúl Hernández Sánchez, Hexing Li, Xiaoyang Zhu, Colin Nuckolls, Michael L. Steigerwald, Shengxiong Xiao
Abstract
This study explores a new mode of contortion in perylene diimides where the molecule is bent, like a bow, along its long axis. These bowed PDIs were synthesized through a facile fourfold Suzuki macrocyclization with aromatic linkers and a tetraborylated perylene diimide that introduces strain and results in a bowed structure. By altering the strings of the bow, the degree of bending can be controlled from flat to highly bent. Through spectroscopy and quantum chemical calculations, it is demonstrated that the energy of the lowest unoccupied orbital can be controlled by the degree of bending in the structures and that the energy of the highest occupied orbital can be controlled to a large extent by the constitution of the aromatic linkers. The important finding is that the bowing results not only in red-shifted absorptions but also more facile reductions.