Conformational Transformations of (C₁₂H₂₅NH₃ ⁺)(Pyridinesulfonate) in the Solid State

The phase-transition behaviors, crystal structures, and dielectric properties of four kinds of simple 1:1 organic salts of (C₁₂H₂₅NH₃ ⁺)(benzenesulfonate) and (C₁₂H₂₅NH₃ ⁺)(pyridine sulfonates) were examined from the viewpoint of intermolecular hydrogen-bonding interactions and dynamic conformational transformation in molecular assemblies. Crystals of (C₁₂H₂₅NH₃ ⁺)(benzenesulfonate) and (C₁₂H₂₅NH₃ ⁺)(3-pyridinesulfonate) were isostructural and solid-solid and solid-liquid-crystal smectic A (SmA) phase transitions were observed. These two crystals formed rodlike cation-anion assemblies. However, the two salts, (C₁₂H₂₅NH₃ ⁺)(2-pyridinesulfonate) and (C₁₂H₂₅NH₃ ⁺)(4-pyridinesulfonate), formed largely bent L-shaped cation-anion conformations. Interesting conformational transformations from rodlike to L-shaped assemblies were observed in (C₁₂H₂₅NH₃ ⁺)(2-pyridinesulfonate) and (C₁₂H₂₅NH₃ ⁺)(3-pyridinesulfonate). Spare the rod: Dynamic conformational transformations from rodlike to L-shaped assemblies were observed in 1:1 simple organic salts.