Single‐Crystal Helical Covalent Polymers with Organic Counter Cations

ABSTRACT Helical polymers, central to many bioactive molecules and polymers, offer distinctive functional properties, yet the precise synthesis and atomic‐level characterization of artificial helical covalent polymers (HCPs) remain challenging. Here, we demonstrate that soft organic counter cations, combined with dynamic spiroborate chemistry, enable the rapid synthesis of hydrogen‐bonded, single‐crystal HCPs, significantly reducing polymerization times compared with analogous systems containing alkali metal cations. Single‐crystal X‐ray diffraction of HCPs prepared from amines or pyridine with their conjugate acid pK a values ranging from 4.63 to 10.71 revealed closely related hydrogen‐bonded helical backbones associated with nearby organic counter cations. Importantly, counter‐cation acidity strongly influences polymerization kinetics and the resulting helical architectures, establishing a previously underexplored strategy for controlling HCP formation. Beyond structural control, these materials exhibit promising solid‐state proton‐conducting properties, with HCP‐TFEA achieving a proton conductivity of 2.8 × 10 −3 S cm −1 at 70°C and 97% relative humidity. These findings demonstrate that rational counter‐cation selection provides an effective approach to accelerate HCP synthesis while simultaneously tuning polymer structure and function, offering new opportunities for the design of dynamic helical polymeric materials.