Time dependent water uptake in Cu3(btc)2 MOF: Identification of different water adsorption states by 1H MAS NMR

• Hydration process in deuterated Cu3(btc)2 MOF is followed using NMR spectroscopy.
• 1H MAS NMR signals indicate different positions of water molecules in the framework.
• Fast exchange between water sites at high water content.

The hydration process in a deuterated Cu3(btc)2 (d-Cu3(btc)2) metal–organic framework (MOF) was followed by 1H solid state NMR. Various hydrated states of d-Cu3(btc)2 are studied at definite time intervals after exposition of the MOF to atmospheric water. 1H MAS NMR spectra indicate different positions of the water molecules inside the Cu3(btc)2 framework, and a distribution of chemical shifts. The change of the different water signals with time is followed by an intensity analysis. Fast exchange dynamics is observed when the amount of water is above two molecules per copper atom.

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