Complementary Hydrogen Bonding Modulates Electronic Properties and Controls Self‐Assembly of Donor/Acceptor Semiconductors

A comprehensive investigation of the complementary H‐bonding‐mediated self‐assembly between dipyrrolo2,3‐b:3′,2′‐e]pyridine (P2P) electron donors and naphthalenediimide/perylenediimide (NDI/PDI) acceptors is reported. The synthesis of parent P2P and several aryl‐substituted derivatives is described, along with their optical, redox, and single‐crystal packing characteristics. The dual functionality of heteroatoms in the P2P/NDI(PDI) assembly, which act as proton donors/acceptors and also contribute to π‐conjugation, leads to H‐bonding‐induced perturbation of electronic levels. Concentration‐dependent NMR and UV/Vis spectroscopic studies revealed a cooperative effect of H‐bonding and π–π stacking interactions. This H‐bonding‐mediated co‐assembly of donor (D) and acceptor (A) components leads to a new charge‐transfer (CT) absorption that can be controlled throughout the visible range. The electronic interactions between D and A were further investigated by time‐dependent DFT, which provided insights into the nature of the CT transition. Electropolymerization of difuryl‐P2P afforded the first conjugated polymer incorporating H‐bonding recognition units in its main chain.