Temperature‐induced solid‐to‐solid transformation in helical homochiral coordination polymers

The reactions of (R)‐ and (S)‐4‐(1‐carboxyethoxy)benzoic acid (H₂CBA) with 1,3‐bis(2‐methyl‐1H‐imidazol‐1‐yl)benzene (1,3‐BMIB) ligands afforded a pair of homochiral coordination polymers (CPs), namely, polyμ‐1,3‐bis(2‐methyl‐1H‐imidazol‐1‐yl)benzene]μ‐(S)‐4‐(1‐carboxylatoethoxy)benzoato]zinc(II)] monohydrate], {Zn(C₁₀H₈O₅)(C₁₄H₁₄N₄)]·H₂O}_n or {Zn{(S)‐CBA}(1,3‐BMIB)]·H₂O}_n ( 1‐L ), and polyμ‐1,3‐bis(2‐methyl‐1H‐imidazol‐1‐yl)benzene]μ‐(R)‐4‐(1‐carboxylatoethoxy)benzoato]zinc(II)] monohydrate] ( 1‐D ). Three kinds of helical chains exist in compounds 1‐D and 1‐L , which are constructed from Zn^II atoms, 1,3‐BMIB ligands and/or CBA^2? ligands. When the as‐synthesized crystals of 1‐L and 1‐D were further heated in the mother liquor or air, polyμ‐1,3‐bis(2‐methyl‐1H‐imidazol‐1‐yl)benzene]μ‐(S)‐4‐(1‐carboxylatoethoxy)benzoato]zinc(II)], Zn(C₁₀H₈O₅)(C₁₄H₁₄N₄)]_n or Zn{(S)‐CBA}(1,3‐BMIB)]_n ( 2‐L ), and polyμ‐1,3‐bis(2‐methyl‐1H‐imidazol‐1‐yl)benzene]μ‐(R)‐4‐(1‐carboxylatoethoxy)benzoato]zinc(II)] ( 2‐D ) were obtained, respectively. The single‐crystal structure analysis revealed that 2‐L and 2‐D only contained one type of helical chain formed by Zn^II atoms and 1,3‐BMIB and CBA^2? ligands, which indicated that the helical chains were reconstructed though solid‐to‐solid transformation. This result not only means the realization of helical transformation, but also gives a feasible strategy to build homochiral CPs.