Intramolecular Hydrogen-Bonded Networks for Tuning Anthraquinone Redox Properties.
- 1School of Molecular Sciences, Arizona State University, Tempe, Arizona85287, United States.
- 2Department of Chemistry, Princeton University, Princeton, New Jersey08544, United States.
Abstract
Intramolecular hydrogen-bonded networks have been designed and synthesized to control quinone redox thermodynamics in a family of anthraquinone (AQ) derivatives. The networks contain imidazole fused to AQ, which is hydrogen-bonded to the AQ carbonyl, and the extended motifs include phenol (P) and benzimidazole (BI). Cyclic voltammetry reveals a systematic anodic displacement of the AQ/AQ•- couple as the hydrogen-bonded network is extended, resulting in a cumulative +440 mV shift. Visible spectroelectrochemistry provides direct reduced-state markers: AQ exhibits AQ•- bands at ∼410 and ∼539 nm, whereas the intramolecular hydrogen-bonded constructs display only blue-shifted AQ•- signatures at ∼490 nm (BI-AQ), ∼505 nm (BIP-AQ), and ∼494 nm (BI2P-AQ), consistent with hydrogen-bond-dependent perturbation of the reduced quinone electronic structure. Infrared spectroelectrochemistry further resolves the underlying hydrogen-bonding interactions, revealing depletion of the neutral AQ ν(C═O) band (∼1667 cm-1) under reductive polarization with the emergence of hydrogen-bonded AQ•- band at ∼1480 cm-1 in the AQ derivatives. Oxidative polarization, yielding the phenoxyl radical, induces benzimidazolium formation and a blue-shifted AQ ν(C═O) band (∼1678 cm-1), highlighting the directional dependence of the perturbation and the role of the AQ carbonyl as a reporter of the interaction with the intramolecular hydrogen-bonded network. Treating the hydrogen-bonding protons quantum mechanically, nuclear-electronic orbital density functional theory calculations show strengthening of the hydrogen bonds cooperatively across the network upon one-electron reduction and oxidation, correctly predicting the observed stabilization of the AQ•- state. These fundamental insights will assist in the design of more precisely tuned catalysts.
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BibTeX
@article{lopez2026intramolecular,
title = {{Intramolecular Hydrogen-Bonded Networks for Tuning Anthraquinone Redox Properties.}},
author = {Edwin J Gonzalez Lopez and Kai Cui and Jang Mok Yoo and Daniel A Heredia and Sharon Hammes-Schiffer and Thomas A Moore and Ana L Moore},
journal = {Journal of the American Chemical Society},
year = {2026},
month = sep,
doi = {10.1021/jacs.6c15431},
url = {https://europepmc.org/article/MED/42937854},
note = {CC BY-NC-ND},
}
RIS
TY - JOUR
TI - Intramolecular Hydrogen-Bonded Networks for Tuning Anthraquinone Redox Properties.
AU - Edwin J Gonzalez Lopez
AU - Kai Cui
AU - Jang Mok Yoo
AU - Daniel A Heredia
AU - Sharon Hammes-Schiffer
AU - Thomas A Moore
AU - Ana L Moore
PY - 2026
DA - 2026/09/01
JO - Journal of the American Chemical Society
DO - 10.1021/jacs.6c15431
UR - https://europepmc.org/article/MED/42937854
AB - Intramolecular hydrogen-bonded networks have been designed and synthesized to control quinone redox thermodynamics in a family of anthraquinone (AQ) derivatives. The networks contain imidazole fused to AQ, which is hydrogen-bonded to the AQ carbonyl, and the extended motifs include phenol (P) and benzimidazole (BI). Cyclic voltammetry reveals a systematic anodic displacement of the AQ/AQ•- couple as the hydrogen-bonded network is extended, resulting in a cumulative +440 mV shift. Visible spectroelectrochemistry provides direct reduced-state markers: AQ exhibits AQ•- bands at ∼410 and ∼539 nm, whereas the intramolecular hydrogen-bonded constructs display only blue-shifted AQ•- signatures at ∼490 nm (BI-AQ), ∼505 nm (BIP-AQ), and ∼494 nm (BI2P-AQ), consistent with hydrogen-bond-dependent perturbation of the reduced quinone electronic structure. Infrared spectroelectrochemistry further resolves the underlying hydrogen-bonding interactions, revealing depletion of the neutral AQ ν(C═O) band (∼1667 cm-1) under reductive polarization with the emergence of hydrogen-bonded AQ•- band at ∼1480 cm-1 in the AQ derivatives. Oxidative polarization, yielding the phenoxyl radical, induces benzimidazolium formation and a blue-shifted AQ ν(C═O) band (∼1678 cm-1), highlighting the directional dependence of the perturbation and the role of the AQ carbonyl as a reporter of the interaction with the intramolecular hydrogen-bonded network. Treating the hydrogen-bonding protons quantum mechanically, nuclear-electronic orbital density functional theory calculations show strengthening of the hydrogen bonds cooperatively across the network upon one-electron reduction and oxidation, correctly predicting the observed stabilization of the AQ•- state. These fundamental insights will assist in the design of more precisely tuned catalysts.
SN - 0002-7863
SN - 1520-5126
ER -