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

Scott, A. J. et al. (2021) Exploiting host-guest chemistry to manipulate magnetic interactions in metallosupramolecular M4L6 tetrahedral cages. Chemical Science, 12(14), pp. 5134-5142. (doi: 10.1039/D1SC00647A)

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 feauture an encapsulated paramagnetic tetrahalometallate ion inside this paramagnetic host giving [MIIX4⊂NiII4L6](OTf)6, where MIIX42− = MnCl42− (2), CoCl42− (5), CoBr42− (6), NiCl42− (7), CuBr42− (8) or [MIIIX4⊂NiII4L6](OTf)7, where MIIIX4− = FeCl4− (3), 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} vertex 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 {MX4}n− guest molecules leads to stronger host-guest magnetic exchange interactions.

• Item Type: Articles
• Additional Information: We thank the EPSRC for funding grants EP/P025986/1 and EP/N01331X/1. EKB, GR and AS thank the British Council, UKIERI grant 2017-18-04. S.P. thanks the VILLUM FONDEN for research grant 13376. We also thank Diamond Light Source for access to synchrotron facilities, award CY22240.
• Status: Published
• Refereed: Yes
• Glasgow Author(s) Enlighten ID: Smythe, Ms Lucy and Regincos Marti, Miss Emma and Murrie, Professor Mark
• Authors: Scott, A. J., Brechin, E. K., Piligkos, S., Rajaraman, G., Murrie, M., Coles, S., Klooster, W., Nichol, G. S., Lusby, P., Smythe, L., Sarkar, A., Vallejo, J., and Regincós Martí, E.
• College/School: College of Science and Engineering > School of Chemistry
• Journal Name: Chemical Science
• Publisher: Royal Society of Chemistry
• ISSN: 2041-6520
• ISSN (Online): 2041-6539
• Published Online: 01 March 2021
• Copyright Holders: Copyright © 2021 The Authors
• First Published: First published in Chemical Science 12(14): 5134-5142
• Publisher Policy: Reproduced under a Creative Commons license