Unveiling Linker-Born Electron Spin Centers in UiO-66-NH2 MOF

TL;DR

This paper discovers a stable NH radical spin center in UiO-66-NH2 MOF, characterized by EPR and DFT, with promising coherence times for quantum sensing applications, opening new avenues for organic radical integration in MOFs.

Contribution

It identifies an intrinsic NH radical spin center in UiO-66-NH2 MOF and characterizes its properties, advancing the use of organic radicals in quantum technologies.

Findings

NH radical spin center identified in UiO-66-NH2

Spin center exhibits long coherence time

Potential for quantum sensing applications

Abstract

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.