UiO-66 framework with an encapsulated spin probe: synthesis and exceptional sensitivity to mechanical pressure

• Published in: Physical chemistry chemical physics : PCCP Vol. 25; no. 2; pp. 13846 - 13853
• Main Authors: Poryvaev, Artem S, Larionov, Kirill P, Albrekht, Yana N, Efremov, Alexander A, Kiryutin, Alexey S, Smirnova, Kristina A, Evtushok, Vasiliy Y, Fedin, Matvey V
• Format: Journal Article
• Language: English
• Published: England Royal Society of Chemistry 24.05.2023
• Subjects: Demand analysis; Electron paramagnetic resonance; Encapsulation; Metal-organic frameworks; Pressure distribution; Pressure effects; Pressure sensors; Synthesis
• ISSN: 1463-9076; 1463-9084
• DOI: 10.1039/d3cp01063e

Probes sensitive to mechanical stress are in demand for the analysis of pressure distribution in materials, and the design of pressure sensors based on metal-organic frameworks (MOFs) is highly promising due to their structural tunability. We report a new pressure-sensing material, which is based on the UiO-66 framework with trace amounts of a spin probe (0.03 wt%) encapsulated in cavities. To obtain this material, we developed an approach for encapsulation of stable nitroxide radical TEMPO ((2,2,6,6-tetramethylpiperidin-1-yl)oxyl) into the micropores of UiO-66 during its solvothermal synthesis. Pressure read-out using electron paramagnetic resonance (EPR) spectroscopy allows monitoring the degradation of the defected MOF structure upon pressurization, where full collapse of pores occurs at as low a pressure as 0.13 GPa. The developed methodology can be used in and ex situ and provides sensitive tools for non-destructive mapping of pressure effects in various materials. The metal-organic framework UiO-66 with embedded nitroxide radicals represents a new strategy for the design of MOF-nitroxide-based pressure sensors with non-invasive EPR detection.