Rotaxane-based transition metal complexes: Effect of the mechanical bond on structure and electronic properties
File(s)
Author(s)
Type
Journal Article
Abstract
Early work by Sauvage revealed that mechanical bonding alters the stability and redox properties of their original catenane metal complexes. However, despite the importance of controlling metal ion properties for a range of applications, these effects have received relatively little attention since. Here we present a series of tri-, tetra-, and pentadentate rotaxane-based ligands and a detailed study of their metal binding behavior and, where possible, compare their redox and electronic properties with their noninterlocked counterparts. The rotaxane ligands form complexes with most of the metal ions investigated, and X-ray diffraction revealed that in some cases the mechanical bond enforces unusual coordination numbers and distorted arrangements as a result of the exclusion of exogenous ligands driven by the sterically crowded binding sites. In contrast, only the noninterlocked equivalent of the pentadentate rotaxane CuII complex could be formed selectively, and this exhibited compromised redox stability compared to its interlocked counterpart. Frozen-solution EPR data demonstrate the formation of an interesting biomimetic state for the tetradentate CuII rotaxane, as well as the formation of stable NiI species and the unusual coexistence of high- and low-spin CoII in the pentadentate framework. Our results demonstrate that readily available mechanically chelating rotaxanes give rise to complexes the noninterlocked equivalent of which are inaccessible, and that the mechanical bond augments the redox behavior of the bound metal ion in a manner analogous to the carefully tuned amino acid framework in metalloproteins.
Date Issued
2019-01-16
Date Acceptance
2018-12-18
Citation
Journal of the American Chemical Society, 2019, 141 (2), pp.879-889
ISSN
0002-7863
Publisher
American Chemical Society (ACS)
Start Page
879
End Page
889
Journal / Book Title
Journal of the American Chemical Society
Volume
141
Issue
2
Copyright Statement
© 2018 American Chemical Society. This document is the Accepted Manuscript version of a Published Work that appeared in final form in Journal of the American Chemical Society, after peer review and technical editing by the publisher. To access the final edited and published work see https://dx.doi.org/10.1021/jacs.8b09715
Identifier
https://pubs.acs.org/doi/10.1021/jacs.8b09715
Subjects
Science & Technology
Physical Sciences
Chemistry, Multidisciplinary
Chemistry
ACTIVE-TEMPLATE SYNTHESIS
LIGANDS DIALING-UP
MACROCYCLIC LIGANDS
PHENANTHROLINE COMPLEXES
SPECTROSCOPIC PROPERTIES
COORDINATION CHEMISTRY
CO-CONFORMATIONS
SPIN-CROSSOVER
SCHIFF-BASE
COBALT(II)
Coordination Complexes
Electron Spin Resonance Spectroscopy
Ligands
Metals, Heavy
Molecular Structure
Oxidation-Reduction
Rotaxanes
Transition Elements
Metals, Heavy
Transition Elements
Rotaxanes
Ligands
Electron Spin Resonance Spectroscopy
Molecular Structure
Oxidation-Reduction
Coordination Complexes
General Chemistry
03 Chemical Sciences
Publication Status
Published
Date Publish Online
2018-12-18