Embedded nano spin sensor for in situ probing of gas adsorption inside porous organic frameworks

Spin-based sensors have attracted considerable attention owing to their high sensitivities. Herein, we developed a metallofullerene-based nano spin sensor to probe gas adsorption within porous organic frameworks. For this, spin-active metallofullerene, Sc₃C₂@C_80, was selected and embedded into a nanopore of a pyrene-based covalent organic framework (Py-COF). Electron paramagnetic resonance (EPR) spectroscopy recorded the EPR signals of Sc₃C₂@C₈₀ within Py-COF after adsorbing N₂, CO, CH₄, CO₂, C₃H₆, and C₃H₈. Results indicated that the regularly changing EPR signals of embedded Sc₃C₂@C₈₀ were associated with the gas adsorption performance of Py-COF. In contrast to traditional adsorption isotherm measurements, this implantable nano spin sensor could probe gas adsorption and desorption with in situ, real-time monitoring. The proposed nano spin sensor was also employed to probe the gas adsorption performance of a metal–organic framework (MOF-177), demonstrating its versatility. The nano spin sensor is thus applicable for quantum sensing and precision measurements.