Encoding metal coordination pathways and nuclearity by molecular knotting
4 affiliations
- 1Department of Chemistry, Fudan University, Shanghai 200438, People’s Republic of China
- 2State Key Laboratory of Organometallic Chemistry, Chinese Academy of Sciences, University of Chinese Academy of Sciences, Shanghai 200032, People’s Republic of China
- 3State Key Laboratory of Molecular Engineering of Polymers and Department of Macromolecular Science, Fudan University, Shanghai 200433, People’s Republic of China
- 4School of Chemistry and Molecular Engineering, East China Normal University, Shanghai 200062, People’s Republic of China
Abstract
Precise control over the nuclearity and spatial organization of metal ions is a central objective in coordination chemistry. Knotting imposes severe geometric constraints on frameworks but has rarely been exploited to organize inequivalent metal-binding sites within a single ligand. Here we report that a molecular cinquefoil knot containing both bidentate and tridentate chelating sites enables programmed metal-ion coordination pathways. Direct metalation affords Mn(II)5-, Fe(II)5-, Co(II)5-, and Cd(II)5-knots through a dinuclear intermediate and an unusual 2-to-5 metal nuclearity progression, even though these metals do not template knot formation. Crystallization of a Mn(II)2-intermediate reveals partial demetalation but retains a Mn(II) center displaying a “3 + 3” coordination mode, whereas all Fe(II) ions in the fully metalated Fe(II)5-knot adopt a “3 + 2” binding geometry. Together with computational simulations, these observations support a stepwise metalation mechanism in which the dinuclear “3 + 3” coordination environment evolves into the “3 + 2” motif of the pentanuclear knot. Although the Ni(II)5- knot cannot be obtained by direct metalation because of slow incorporation, it forms readily via transmetalation from a Zn(II)5-knot. Circular dichroism measurements show that chiral expression is dictated by the overall ligand arrangement rather than the identity of the metal ions. The work demonstrates molecular knotting as a strategy for pathway-controlled multi-metallic assembly.
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BibTeX
@article{chi2026encoding,
title = {{Encoding metal coordination pathways and nuclearity by molecular knotting}},
author = {Guanyu Chi and Bo Li and Hai-Na Feng and Zhi-Hui Zhang and Heng Wang and Xiaopeng Li and Liang Zhang},
journal = {Proceedings of the National Academy of Sciences of the United States of America},
year = {2026},
month = oct,
doi = {10.1073/pnas.2610851123},
url = {https://doi.org/10.1073/pnas.2610851123},
note = {CC BY-NC-ND 4.0},
}
RIS
TY - JOUR
TI - Encoding metal coordination pathways and nuclearity by molecular knotting
AU - Guanyu Chi
AU - Bo Li
AU - Hai-Na Feng
AU - Zhi-Hui Zhang
AU - Heng Wang
AU - Xiaopeng Li
AU - Liang Zhang
PY - 2026
DA - 2026/10/27
JO - Proceedings of the National Academy of Sciences of the United States of America
DO - 10.1073/pnas.2610851123
UR - https://doi.org/10.1073/pnas.2610851123
AB - Precise control over the nuclearity and spatial organization of metal ions is a central objective in coordination chemistry. Knotting imposes severe geometric constraints on frameworks but has rarely been exploited to organize inequivalent metal-binding sites within a single ligand. Here we report that a molecular cinquefoil knot containing both bidentate and tridentate chelating sites enables programmed metal-ion coordination pathways. Direct metalation affords Mn(II)5-, Fe(II)5-, Co(II)5-, and Cd(II)5-knots through a dinuclear intermediate and an unusual 2-to-5 metal nuclearity progression, even though these metals do not template knot formation. Crystallization of a Mn(II)2-intermediate reveals partial demetalation but retains a Mn(II) center displaying a “3 + 3” coordination mode, whereas all Fe(II) ions in the fully metalated Fe(II)5-knot adopt a “3 + 2” binding geometry. Together with computational simulations, these observations support a stepwise metalation mechanism in which the dinuclear “3 + 3” coordination environment evolves into the “3 + 2” motif of the pentanuclear knot. Although the Ni(II)5- knot cannot be obtained by direct metalation because of slow incorporation, it forms readily via transmetalation from a Zn(II)5-knot. Circular dichroism measurements show that chiral expression is dictated by the overall ligand arrangement rather than the identity of the metal ions. The work demonstrates molecular knotting as a strategy for pathway-controlled multi-metallic assembly.
SN - 0027-8424
SN - 1091-6490
ER -