Halide ion directed templation effect of quadruple-stranded helicates
Yang Liu, Zhiyuan Jiang, Yu‐Ming Guan, Qixia Bai, Zhe Zhang, Yiming Li, He Zhao, Ting‐Zheng Xie, Ming Wang, Pingshan Wang, Tun Wu
Abstract
The allosteric effect, described as biological enzymes’ conformation change to accommodate specific substrates, plays an important role in metabolic regulation. However, well-organized aggregation of synthetic receptors into high-order supramolecular structures with different conformations and functions in response to a variety of external stimuli presents a formidable challenge. Herein, a series of quadruple-stranded helicates are created through the templation effect of halide ions in a library of metallo-macrocycles. Single-crystal X-ray diffraction unambiguously confirms that the four intertwined strands are bridged with halide ions via eight robust C–H···X¯ hydrogen bonds, four anion-π interactions, and two electrostatic contacts. The binding of I¯ results in a D2-symmetric helicate, while the Br¯ or Cl¯ adducts display asymmetric infrastructures. Furthermore, the templation effect exhibits non-thermodynamically controlled, high selectivity toward I¯ due to its nucleophilicity toward breaking up partial coordination bonds.