Authors
Guanyu Chi, Bo Li, Hai-Na Feng, Zhi-Hui Zhang, Heng Wang, Xiaopeng Li, Liang Zhang
Published in
Proceedings of the National Academy of Sciences of the United States of America. Volume 123. Issue 44. Pages e2610851123. Nov 03, 2026. Epub Oct 27, 2026.
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.
PMID:
42945258
Bibliographic data and abstract were imported from PubMed on 28 Oct 2026.
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