Tuning Conjugation and Charge Transport in Supramolecular Semiconductors via Hydrogen-Bonding Position.

Precise control over conjugation pathways is essential for developing high-performance organic semiconductors, particularly in hydrogen-bonded systems where subtle structural variations strongly influence hydrogen bond strength, molecular planarity, supramolecular organization, and charge transport. We demonstrate that the relative positioning of hydrogen-bonding with respect to a π-conjugated core enables the modulation of conjugation pathways through controlled intra- or intermolecular interactions. A series of diketopyrrolopyrrole small molecules bearing amides at defined distances from the conjugated backbone was designed to selectively favor distinct hydrogen-bonding types and strengths. Our combined approach, including density functional theory, vibrational and electronic spectroscopies, electrochemistry, and solid-state characterization, reveals that proximal amide groups favor intramolecular hydrogen-bonding, disrupting backbone planarity and limiting effective π-conjugation. In contrast, distal amides promote intermolecular hydrogen-bonding, sometimes involving DPP carbonyl groups, leading to extended conjugation pathways and enhanced supramolecular organization in the solid state. This modulation of hydrogen-bond topology and strength results in markedly different charge-carrier dynamics and transport, evidenced by electrodeless photoconductivity measurements and organic field-effect transistors. Overall, this work establishes hydrogen-bond and strength, rather than hydrogen-bonding alone, as key molecular design parameter to modulate conjugation extension and charge transport in hydrogen-bonded semiconductors, providing general insights for designing functional supramolecular electronic materials.