Issue 15, 2019

Supramolecular chirality transformation driven by monodentate ligand binding to a coordinatively unsaturated self-assembly based on C3-symmetric ligands

Abstract

Monodentate ligand binding is facilitated by supramolecular chirality transformations from propeller-shaped chirality into single-twist chirality by altering the self-assembly of C3-symmetric chiral ligands. The C3-symmetric chiral ligands (ImR3Bz and ImS3Bz) contain three chiral imidazole side arms (ImR and ImS) at the 1,3,5-positions of a central benzene ring. Upon coordination to zinc ions (Zn2+), which have a tetrahedral coordination preference, the C3-symmetric chiral ligands assemble, in a stepwise manner, into a propeller-shaped assembly with a general formula (Im(RorS)3Bz)4(Zn2+)3. In this structure each Zn2+ ion coordinates to the three individual imidazole side arms. The resulting assembly is formally coordinatively unsaturated (coordination number, n = 3) and capable of accepting monodentate co-ligands (imidazole: ImH2) to afford a coordinatively saturated assembly [(ImH2)3(ImR3Bz)4(Zn2+)3]. The preformed propeller-shaped chirality is preserved during this transformation. However, an excess of the monodentate co-ligand (ImH2/Zn2+ molar ratio of ∼1.7) alters the propeller-shaped assembly into a stacked dimer assembly [(ImH2)m(ImR3Bz)2(Zn2+)3] (m = 4–6) with single-twist chirality. This switch alters the degree of enhancement and the circular dichroism (CD) pattern, suggesting a structural transition into a chiral object with a different shape. This architectural chirality transformation presents a new approach to forming dynamic coordination-assemblies, which have transformable geometric chiral structures.

Graphical abstract: Supramolecular chirality transformation driven by monodentate ligand binding to a coordinatively unsaturated self-assembly based on C3-symmetric ligands

Supplementary files

Article information

Article type
Edge Article
Submitted
24 1月 2019
Accepted
01 3月 2019
First published
05 3月 2019
This article is Open Access

All publication charges for this article have been paid for by the Royal Society of Chemistry
Creative Commons BY license

Chem. Sci., 2019,10, 4236-4245

Supramolecular chirality transformation driven by monodentate ligand binding to a coordinatively unsaturated self-assembly based on C3-symmetric ligands

Y. Imai and J. Yuasa, Chem. Sci., 2019, 10, 4236 DOI: 10.1039/C9SC00399A

This article is licensed under a Creative Commons Attribution 3.0 Unported Licence. You can use material from this article in other publications without requesting further permissions from the RSC, provided that the correct acknowledgement is given.

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