Issue 14, 2021

Exploiting host–guest chemistry to manipulate magnetic interactions in metallosupramolecular M4L6 tetrahedral cages

Abstract

Reaction of Ni(OTf)2 with the bisbidentate quaterpyridine ligand L results in the self-assembly of a tetrahedral, paramagnetic cage [NiII4L6]8+. By selectively exchanging the bound triflate from [OTf⊂NiII4L6](OTf)7 (1), we have been able to prepare a series of host–guest complexes that feature an encapsulated paramagnetic tetrahalometallate ion inside this paramagnetic host giving [MIIX4⊂NiII4L6](OTf)6, where MIIX42− = MnCl42− (2), CoCl42− (5), CoBr42− (6), NiCl42− (7), and CuBr42− (8) or [MIIIX4⊂NiII4L6](OTf)7, where MIIIX4 = FeCl4 (3) and FeBr4 (4). Triflate-to-tetrahalometallate exchange occurs in solution and can also be accomplished through single-crystal-to-single-crystal transformations. Host–guest complexes 1–8 all crystallise as homochiral racemates in monoclinic space groups, wherein the four {NiN6} vertexes within a single Ni4L6 unit possess the same Δ or Λ stereochemistry. Magnetic susceptibility and magnetisation data show that the magnetic exchange between metal ions in the host [NiII4] complex, and between the host and the MX4n guest, are of comparable magnitude and antiferromagnetic in nature. Theoretically derived values for the magnetic exchange are in close agreement with experiment, revealing that large spin densities on the electronegative X-atoms of particular MX4n guest molecules lead to stronger host–guest magnetic exchange interactions.

Graphical abstract: Exploiting host–guest chemistry to manipulate magnetic interactions in metallosupramolecular M4L6 tetrahedral cages

Supplementary files

Article information

Article type
Edge Article
Submitted
02 Feb 2021
Accepted
28 Feb 2021
First published
01 Mar 2021
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., 2021,12, 5134-5142

Exploiting host–guest chemistry to manipulate magnetic interactions in metallosupramolecular M4L6 tetrahedral cages

A. J. Scott, J. Vallejo, A. Sarkar, L. Smythe, E. Regincós Martí, G. S. Nichol, W. T. Klooster, S. J. Coles, M. Murrie, G. Rajaraman, S. Piligkos, P. J. Lusby and E. K. Brechin, Chem. Sci., 2021, 12, 5134 DOI: 10.1039/D1SC00647A

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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