Abstract
<jats:p>π-Conjugated backbones depend on torsional coplanarity for efficient charge transport and strong intermolecular coupling, yet most conformational-control strategies lock a backbone into a single geometry, requiring a redesigned monomer for every new conformation. Herein hydrogen bonded imidazopyridine oligomers (HIPO) are introduced in which a single repeat unit carries both a hydrogen-bond donor and acceptor, and whose imidazole tautomerism gives access to two distinct coplanar geometries, a six-membered trans and a seven-membered cis hydrogen-bonded ring. Density functional theory on an imidazopyridine dimer reveals four tautomeric states with two coplanar minima, and the resulting Boltzmann torsional distributions are propagated along a polymer chain through a Bayesian belief-propagation model built on a tautomer transition network. Because the forward and reverse transition matrices are non-reversible, the model predicts a directional, chain-length-dependent funneling towards mostly trans at one chain end and fully cis at the other, bridged by a topologically required intermediate tautomer. Variable-temperature and solvent-dependent UV-Vis and fluorescence spectroscopy of the oligomers allow the evaluation of the model within the context of steric and intermolecular interactions: HIPO-a (branched sidechain) behaves as a rigid, all-trans J-aggregate, while HIPO-b (linear sidechain) shows significant solvatochromic and thermochromic behavior consistent with interconversion between cis/trans conformers along the oligomer conjugated backbones. These results suggest tautomer-encoded, directional conformational control as a design principle for conjugated backbones, moving beyond the binary choice of torsional rigidity or free rotation.</jats:p>