Skip to main page content
U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

Https

The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
. 2022 Apr 20;51(16):6212-6219.
doi: 10.1039/d2dt00312k.

Conformationally dynamic copper coordination complexes

Bronte J Charette  1 , Paul J Griffin  1 , Claire M Zimmerman  1 , Lisa Olshansky  1
Affiliations

Conformationally dynamic copper coordination complexes

Bronte J Charette et al. Dalton Trans. .

Abstract

The interplay between oxidation state and coordination geometry dictates both kinetic and thermodynamic properties underlying electron transfer events in copper coordination complexes. An ability to stabilize both CuI and CuII oxidation states in a single conformationally dynamic chelating ligand allows access to controlled redox reactivity. We report an analysis of the conformational dynamics of CuI complexes bearing dipicolylaniline (dpaR) ligands, with ortho-aniline substituents R = H and R = OMe. Variable temperature NMR spectroscopy and electrochemical experiments suggest that in solution at room temperature, an equilibrium exists between two conformers. Two metal-centered redox events are observed which, bolstered by structural information from single crystal X-ray diffraction and solution information from EPR and NMR spectroscopies, are ascribed to the CuII/I couple in planar and tetrahedral conformations. Activation and equilibrium parameters for these structural interconversions are presented and provide entry to leveraging redox-triggered conformational dynamics at Cu.

PubMed Disclaimer

Figures

Figure 1.
Figure 1.
Single crystal XRD ORTEP diagrams of (a) {[Cu(dpaOMe)]2(µ-Cl)}{CuCl2} and (b) [CuCl(dpaOMe)][PF6] with thermal ellipsoids shown at 50 % probability. H-atoms and counterions are omitted for clarity.
Figure 2.
Figure 2.
X-band EPR spectra (black) and simulations (red) of CuCl2(dpaH) (top), and [CuCl(dpaOMe)][PF6] (bottom) in frozen solutions of 1:1 toluene:DMF collected at 50 K. Simulations parameters are tabulated in the supporting information.
Figure 3.
Figure 3.
CVs of CuI (black) and CuII (green) complexes with dpaH (top), and dpaOMe (bottom). Complexes are 1 mM in DMF containing 0.1 M [Bu4N][PF6] supporting electrolyte. Data were collected at a glassy carbon working electrode, with a platinum wire counter electrode, and a silver wire pseudo-reference electrode using a scan rate of 100 mV s−1. Open circuit potentials are indicated by arrowhead.
Figure 4.
Figure 4.
Partial 1H-NMR spectra (500 MHz) of CuCl(dpaOMe) in d2-DCM showing the aromatic proton resonances over the temperature range of 233–298 K.
Scheme 1.
Scheme 1.
Synthetic procedure for [CuCl(dpaR)]+/0 complexes. Structures depict those that exist in solution. The preparation of CuCl2(dpaH) has previously been reported.
Scheme 2.
Scheme 2.
Model for conformational equilibria observed.
See this image and copyright information in PMC

References

    1. Solomon EI, Heppner DE, Johnston EM, Ginsbach JW, Cirera J, Qayyum M, Kieber-Emmons MT, Kjaergaard CH, Hadt RG and Tian L, Chem. Rev, 2014, 114, 3659–3853. - PMC - PubMed
    1. Arcos-López T, Schuth N and Quintanar L, The Type 1 Blue Copper Site: From Electron Transfer to Biological Function, De Gruyter, Berlin, Boston, 2020. - PubMed
    1. Vallee BL and Williamst RJP, Proc. Natl. Acad. Sci, 1967, 59, 498–505. - PMC - PubMed
    1. Qin L, Liu J, Mills DA, Proshlyakov DA, Hiser C and Ferguson-Miller S, Biochemistry, 2009, 48, 5121–5130. - PMC - PubMed
    1. Corfield PWR, Ceccarelli C, Glick MD, Moy IWY, Ochrymowycz LA and Rorabacher DB, J. Am. Chem. Soc, 1985, 107, 2399–2404.