Cage Geometry Reorganizes N···C Contacts While Preserving Nitrogen Spin Localization in N@C60 and N@C70: A DFT Study
- 1Ahmet Erdoğan Vocational School of Health Services, Zonguldak Bülent Ecevit University, İbn-i Sina Campus, 67600 Zonguldak, Türkiye
- 2Department of Physics Engineering, Faculty of Engineering, Hacettepe University, 06800 Ankara, Türkiye
Abstract
Endohedral nitrogen fullerenes are promising candidates for molecular spin qubits and quantum sensing. We compare nitrogen spin localization and N···C contact topology in N@C60 and N@C70. Baseline structural, vibrational, electronic, population, spin density, noncovalent interaction (NCI), and quantum theory of atoms in molecules (QTAIM) analyses used UB3LYP/6-31G(d). Counterpoise-corrected interaction energies were calculated using UB3LYP-D3(BJ)/def2-TZVP, with def2-QZVP checks. QTAIM sensitivity was assessed at fixed geometries using UB3LYP/def2-TZVP and UωB97X-D/def2-TZVP. Encapsulation leaves both cages essentially unperturbed: selected vibrational shifts are ≤0.8 cm−1 and HOMO–LUMO gap changes are ≤0.007 eV. Frontier orbitals remain cage-dominated, whereas Mulliken and Hirshfeld analyses assign 94–99% of the spin population to nitrogen, without substantial charge transfer. Counterpoise-corrected def2-TZVP interaction energies are −9.09 and −8.55 kcal mol−1, respectively; def2-QZVP changes each by <0.05 kcal mol−1. NCI/QTAIM descriptors indicate weak, low-density N···C contacts. N@C60 retains 60 connections across all three tested levels; N@C70 has eight at baseline and the same six in both def2-TZVP calculations. Thus, extensive and restricted contact networks remain distinct, although the exact N@C70 count and local descriptors depend on computational level. Predominantly nitrogen-centered spin therefore accompanies different surrounding contact topologies in cages that differ in size and shape.
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BibTeX
@article{gocen2026cage,
title = {{Cage Geometry Reorganizes N···C Contacts While Preserving Nitrogen Spin Localization in N@C60 and N@C70: A DFT Study}},
author = {Tuğba Göcen and Sevgi Haman Bayarı},
journal = {Nanomaterials},
year = {2026},
month = oct,
doi = {10.3390/nano16211349},
url = {https://www.mdpi.com/2079-4991/16/21/1349},
note = {CC BY 4.0},
}
RIS
TY - JOUR
TI - Cage Geometry Reorganizes N···C Contacts While Preserving Nitrogen Spin Localization in N@C60 and N@C70: A DFT Study
AU - Tuğba Göcen
AU - Sevgi Haman Bayarı
PY - 2026
DA - 2026/10/24
JO - Nanomaterials
DO - 10.3390/nano16211349
UR - https://www.mdpi.com/2079-4991/16/21/1349
AB - Endohedral nitrogen fullerenes are promising candidates for molecular spin qubits and quantum sensing. We compare nitrogen spin localization and N···C contact topology in N@C60 and N@C70. Baseline structural, vibrational, electronic, population, spin density, noncovalent interaction (NCI), and quantum theory of atoms in molecules (QTAIM) analyses used UB3LYP/6-31G(d). Counterpoise-corrected interaction energies were calculated using UB3LYP-D3(BJ)/def2-TZVP, with def2-QZVP checks. QTAIM sensitivity was assessed at fixed geometries using UB3LYP/def2-TZVP and UωB97X-D/def2-TZVP. Encapsulation leaves both cages essentially unperturbed: selected vibrational shifts are ≤0.8 cm−1 and HOMO–LUMO gap changes are ≤0.007 eV. Frontier orbitals remain cage-dominated, whereas Mulliken and Hirshfeld analyses assign 94–99% of the spin population to nitrogen, without substantial charge transfer. Counterpoise-corrected def2-TZVP interaction energies are −9.09 and −8.55 kcal mol−1, respectively; def2-QZVP changes each by <0.05 kcal mol−1. NCI/QTAIM descriptors indicate weak, low-density N···C contacts. N@C60 retains 60 connections across all three tested levels; N@C70 has eight at baseline and the same six in both def2-TZVP calculations. Thus, extensive and restricted contact networks remain distinct, although the exact N@C70 count and local descriptors depend on computational level. Predominantly nitrogen-centered spin therefore accompanies different surrounding contact topologies in cages that differ in size and shape.
SN - 2079-4991
ER -