Su Pingru, Wei Biaowen, Guo Chenxing, Hu Yaqi, Tang Runxu, Zhang Shunran, He Chuanxin, Lin Jing, Yu Xiujun, Chen Zhi, Li Haiyang, Wang Heng, Li Xiaopeng
College of Chemistry and Environmental Engineering, Shenzhen University, Shenzhen 518060, Guangdong, China.
School of Biomedical Engineering, Shenzhen University, Shenzhen 518060, China.
J Am Chem Soc. 2023 Feb 8;145(5):3131-3145. doi: 10.1021/jacs.2c12504. Epub 2023 Jan 25.
In biological systems, many biomacromolecules (, heme proteins) are capable of switching their states reversibly in response to external stimuli, endowing these natural architectures with a high level of diversity and functionality. Although tremendous efforts have been made to advance the complexity of artificial supramolecules, it remains a challenge to construct metallo-supramolecular systems that can carry out reversible interconversion among multiple states. Here, a pH-responsive tridentate ligand, 2,6-di(1-imidazole-2-yl)pyridine (HDAP), is incorporated into the multitopic building block for precise construction of giant metallo-supramolecular hexagonal wreaths with three metal ions, , Fe(II), Co(II), and Ni(II), through coordination-driven self-assembly. In particular, a Co-linked wreath enables reversible interconversion among four states in response to pH and oxidant/reductant with highly efficient conversion without losing structural integrity. During the state interconversion cycles, the physical properties of the assembled constructs are finely tuned, including the charge states of the backbone, valency of metal ions, and paramagnetic/diamagnetic features of complexes. Such discrete wreath structures with a charge-switchable backbone further facilitate layer-by-layer assembly of metallo-supramolecules on the substrate.
在生物系统中，许多生物大分子（如血红素蛋白）能够响应外部刺激而可逆地切换其状态，赋予这些天然结构高度的多样性和功能性。尽管人们已经付出巨大努力来提高人工超分子的复杂性，但构建能够在多种状态之间进行可逆相互转化的金属超分子体系仍然是一项挑战。在此，一种pH响应性三齿配体2,6-二（1-咪唑-2-基）吡啶（HDAP）被引入到多官能团构建模块中，通过配位驱动的自组装精确构建出含有三种金属离子（即Fe(II)、Co(II)和Ni(II)）的巨型金属超分子六边形环。特别地，一个由钴连接的环能够响应pH值以及氧化剂/还原剂在四种状态之间进行可逆相互转化，且转化效率高，同时不会失去结构完整性。在状态相互转化循环过程中，组装体的物理性质被精细调控，包括主链的电荷状态、金属离子的化合价以及配合物的顺磁/抗磁特性。这种具有可电荷切换主链的离散环结构进一步促进了金属超分子在基底上的逐层组装。
