Ligand Curvature Controls the Size of Self-Assembled Twisted Metallacycles
5 affiliations
- 1Institute of Chemistry and Center for Nanoscience and Nanotechnology
- 2Hebrew University
- 3Universität Bonn, Gerhard-Domagk-Straße, Bonn, Germany, 153121
- 4Chemical Research Support Unit
- 5Weizmann Institute of Science
Abstract
Coordination-driven self-assembly often yields dynamic libraries of macrocycles whose size distribution is difficult to control, and ligand-design strategies for directing such equilibria have so far been limited to discrete changes in coordination angles. Here we introduce the first twisted metallacycles, in which ligand curvature is tuned through the tether-to-twist approach. Two twistacene dipyridyl ligands with only a 6° difference in the overall bend: the nearly planar Pl (14° twist) and the twisted Tw (34° twist), assemble with (dppp)Pd(II) and (dppp)Pt(II) corners, {M}, into dynamic equilibria between rhomboidal {M} 2 L 2 and hexagonal {M} 3 L 3 metallacycles. NMR, nanoESI-MS and X-ray crystallography show that racemic ligands self-sort with high fidelity: socially, into heterochiral meso {M} 2 L 2 rhomboids, and narcissistically, into homochiral {M} 3 L 3 hexagons. Van 't Hoff analysis shows ring expansion to be endothermic and entropy-driven throughout, with an enthalpic cost rising from 6–10 kJ mol-1 for Pl to 17–18 kJ mol-1 for Tw . This is explained by increased strain energy for mismatched planar ligands in {M} 2 L 2 assemblies. A few degrees of backbone curvature therefore reshape the free-energy landscape of coordination-driven self-assembly.
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BibTeX
@misc{shioukhi2026ligand,
title = {{Ligand Curvature Controls the Size of Self-Assembled Twisted Metallacycles}},
author = {Israa Shioukhi and Hannah Wessely and Benny Bogoslavsky and Yael Diskin-Posner and Arne Lützen and Ori Gidron},
howpublished = {ChemRxiv},
year = {2026},
month = sep,
doi = {10.26434/chemrxiv.15008143/v1},
url = {https://chemrxiv.org/doi/full/10.26434/chemrxiv.15008143/v1},
note = {CC BY},
}
RIS
TY - UNPB
TI - Ligand Curvature Controls the Size of Self-Assembled Twisted Metallacycles
AU - Israa Shioukhi
AU - Hannah Wessely
AU - Benny Bogoslavsky
AU - Yael Diskin-Posner
AU - Arne Lützen
AU - Ori Gidron
PY - 2026
DA - 2026/09/01
PB - ChemRxiv
DO - 10.26434/chemrxiv.15008143/v1
UR - https://chemrxiv.org/doi/full/10.26434/chemrxiv.15008143/v1
AB - Coordination-driven self-assembly often yields dynamic libraries of macrocycles whose size distribution is difficult to control, and ligand-design strategies for directing such equilibria have so far been limited to discrete changes in coordination angles. Here we introduce the first twisted metallacycles, in which ligand curvature is tuned through the tether-to-twist approach. Two twistacene dipyridyl ligands with only a 6° difference in the overall bend: the nearly planar Pl (14° twist) and the twisted Tw (34° twist), assemble with (dppp)Pd(II) and (dppp)Pt(II) corners, {M}, into dynamic equilibria between rhomboidal {M} 2 L 2 and hexagonal {M} 3 L 3 metallacycles. NMR, nanoESI-MS and X-ray crystallography show that racemic ligands self-sort with high fidelity: socially, into heterochiral meso {M} 2 L 2 rhomboids, and narcissistically, into homochiral {M} 3 L 3 hexagons. Van 't Hoff analysis shows ring expansion to be endothermic and entropy-driven throughout, with an enthalpic cost rising from 6–10 kJ mol-1 for Pl to 17–18 kJ mol-1 for Tw . This is explained by increased strain energy for mismatched planar ligands in {M} 2 L 2 assemblies. A few degrees of backbone curvature therefore reshape the free-energy landscape of coordination-driven self-assembly.
ER -