Conjugated NDI–Donor Polymers: Exploration of Donor Size and Electrostatic Complementarity

Conjugated donor–acceptor copolymers comprised of electron-deficient 1,4,5,8-naphthalenetetracarboxylic diimide (NDI) linked to a series of relatively electron-rich aromatics via ethynyl spacers were synthesized and characterized. While LUMO levels remained constant at −3.75 eV, HOMO levels were sensitive to the relatively electron-rich aromatic donors and systematically tuned from −5.68 to −5.17 eV. Regardless of the electron-rich comonomer, fluorescence and X-ray diffraction data were consistent with the polymer chains being assembled through the stacking of NDI moieties in an offset face-to-face fashion rather than alternating donor–acceptor stacks.