Nucleus-Independent Chemical Shifts in disordered nanoporous carbons are governed by the long-range magnetic response of the carbon framework
- 1Yusuf Hamied Department of Chemistry
- 2University of Cambridge
Abstract
Nanoporous carbons are widely used in energy storage, gas storage, and separation technologies due to their high surface area, porosity, and electrical conductivity. Understanding atomic-scale structure is critical for interpreting performance, yet disorder greatly complicates characterization. NMR chemical shifts of adsorbed molecules have emerged as a probe of structural disorder, but how nucleus-independent chemical shifts (NICS) relate to structure in realistic, disordered carbons remains poorly understood. Here, we generate realistic nanoporous carbon structures using molecular dynamics simulations and compute pore-averaged NICS using density functional theory, reproducing experimentally observed negative values across commercial nanoporous carbons. We find a moderate correlation between sp 2 domain area and NICS, indicating that domain size alone is a poor predictor of the observed shifts, while NICS value also weakly correlate with heteroatom content and 6-membered ring fraction. Instead, decomposing local shielding from non-local contributions shows that the framework's bulk magnetic susceptibility, which implicitly encodes domain size, packing arrangement and defects, dominates the pore-averaged response. These results reframe NICS as a reporter of the framework's collective magnetic susceptibility, rather a local probe of isolated aromatic environments. This position NMR as a quantitative tool for characterizing functional disorder in nanoporous carbons and will help establish a link between framework architecture and performance.
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BibTeX
@misc{kress2026nucleusindependent,
title = {{Nucleus-Independent Chemical Shifts in disordered nanoporous carbons are governed by the long-range magnetic response of the carbon framework}},
author = {Thomas Kress and Xinyu Liu and Alexander C. Forse},
howpublished = {ChemRxiv},
year = {2026},
month = oct,
doi = {10.26434/chemrxiv.15009879/v1},
url = {https://chemrxiv.org/doi/full/10.26434/chemrxiv.15009879/v1},
note = {CC BY},
}
RIS
TY - UNPB
TI - Nucleus-Independent Chemical Shifts in disordered nanoporous carbons are governed by the long-range magnetic response of the carbon framework
AU - Thomas Kress
AU - Xinyu Liu
AU - Alexander C. Forse
PY - 2026
DA - 2026/10/05
PB - ChemRxiv
DO - 10.26434/chemrxiv.15009879/v1
UR - https://chemrxiv.org/doi/full/10.26434/chemrxiv.15009879/v1
AB - Nanoporous carbons are widely used in energy storage, gas storage, and separation technologies due to their high surface area, porosity, and electrical conductivity. Understanding atomic-scale structure is critical for interpreting performance, yet disorder greatly complicates characterization. NMR chemical shifts of adsorbed molecules have emerged as a probe of structural disorder, but how nucleus-independent chemical shifts (NICS) relate to structure in realistic, disordered carbons remains poorly understood. Here, we generate realistic nanoporous carbon structures using molecular dynamics simulations and compute pore-averaged NICS using density functional theory, reproducing experimentally observed negative values across commercial nanoporous carbons. We find a moderate correlation between sp 2 domain area and NICS, indicating that domain size alone is a poor predictor of the observed shifts, while NICS value also weakly correlate with heteroatom content and 6-membered ring fraction. Instead, decomposing local shielding from non-local contributions shows that the framework's bulk magnetic susceptibility, which implicitly encodes domain size, packing arrangement and defects, dominates the pore-averaged response. These results reframe NICS as a reporter of the framework's collective magnetic susceptibility, rather a local probe of isolated aromatic environments. This position NMR as a quantitative tool for characterizing functional disorder in nanoporous carbons and will help establish a link between framework architecture and performance.
ER -