Metal-organic frameworks (MOFs), with their high porosity and large internal surface area, provide versatile platforms for integrating spin centers with potential applications in catalysis and quantum sensing. Here, we identify a stable NH radical spin center in UiO-66-NH2, a zirconium-based MOF with aminoterephthalic acid (TPA-NH2) linkers. Using electron paramagnetic resonance spectroscopy and density functional theory calculations, we determine the nature and spin Hamiltonian parameters of this radical. We also demonstrate that the NH spin center exhibits a relatively long coherence time, making it a strong candidate for quantum sensing. Since this spin center is intrinsic to TPA-NH2 linkers, our findings open new directions for leveraging organic radicals in MOFs for quantum technologies beyond the UiO-66-NH2 family.
@article{arxiv.2412.11591,
title = {Unveiling Linker-Born Electron Spin Centers in UiO-66-NH2 MOF},
author = {Timur Biktagirov and Eugenio Otal and Leopold Trost and Patrick Dörflinger and Katsuya Teshima and Olga Trukhina and Daniel Klose and Wolf Gero Schmidt and Anastasiia Kultaeva},
journal= {arXiv preprint arXiv:2412.11591},
year = {2025}
}