Enantiomeric Cobalt(II)‐Based Frameworks with Various Helical Structures Formed by Achiral N‐/O‐Mixed Rigid Ligands

This study successfully constructed chiral functional materials using achiral rigid ligands H 2 mpa (2‐methoxyterephthalic acid) and 1,4‐dib (1,4‐di(1 H‐imidazol‐1‐yl)benzene) through a spontaneous resolution process. Under hydrothermal condition, enantiomeric coordination polymers HU8‐P (space group P 4 1 ) and HU8‐M (space group P 4 3 , formula {[Co(mpa)(1,4‐dib)]·H 2 O} n ) are synthesized. Structural analysis reveals that in HU8‐P, the Co(II) centers are interconnected along the c‐axis via mpa 2 − anions and 1,4‐dib ligands, forming a triple‐helical system comprising right‐handed mpa‐Co chains, right‐handed 1,4‐dib‐Co chains, and left‐handed mpa‐Co‐1,4‐dib hybrid chains. As enantiomer, helical structures from HU8‐M present a completely mirror‐symmetrical configuration: left‐handed mpa‐Co chains, left‐handed 1,4‐dib‐Co chains and right‐handed mpa‐Co‐1,4‐dib chains. These helical channels display cross‐sectional dimensions of 1.1 × 1.1, 1.1 × 0.8 and 0.8 × 0.8 nm, respectively, which collectively assemble into a fivefold interpenetrated topological network through sophisticated 3D interpenetration. Notably, physical characterization demonstrates the simultaneous presence of closed ferroelectric hysteresis loops and antiferromagnetic behavior in this material system, revealing distinctive multiferroic characteristics.