Modulation of Conjugation Pathways and Charge Transport in Supramolecular Semiconductors via Hydrogen-Bonding Topology

Precise control over conjugation pathways is essential for the development of high-performance organic semiconductors, particularly in hydrogen-bonded systems where subtle structural variations can strongly influence molecular planarity, supramolecular organization, and charge transport. Here, we demonstrate that the relative positioning of hydrogen-bonding motifs with respect to a π-conjugated core enables the modulation of conjugation pathways through controlled intra- or intermolecular hydrogen-bonding. A series of thiophene-capped diketopyrrolopyrrole (DPP) small molecules bearing amide functionalities at well-defined distances from the conjugated backbone was designed to selectively favor distinct hydrogen-bonding topologies. A combined experimental and theoretical approach, including density functional theory calculations, vibrational and electronic spectroscopies, electrochemistry, and solid-state characterization, reveals that proximal amide groups favor intramolecular hydrogen-bonding that disrupts backbone planarity and limits effective π-conjugation. In contrast, distal amide placement promotes intermolecular hydrogen-bonding involving the DPP carbonyl groups, leading to extended conjugation pathways and enhanced supramolecular organization in the solid state. This modulation of hydrogen-bond topology results in markedly different charge-carrier dynamics and transport characteristics, as evidenced by electrodeless photoconductivity measurements and organic field-effect transistor devices. Overall, this work establishes hydrogen-bond topology, rather than hydrogen-bonding alone, as a key molecular design parameter for the modulation of conjugation extension and charge transport in hydrogen-bonded small-molecule semiconductors, providing general insights for the rational design of functional supramolecular electronic materials.