To continue exploring the origin of the Δδ values in Ni3(HITP)2, the ion investigated via NMR was varied. Preliminary data showed poor resolution in 1 H NMR spectra, suggesting a small Δδ and making identification and accurate quantification of NEt4 + cation environments difficult (SI Figure ). Further, F NMR was used to investigate the adsorption environments for TFSI -anions in Ni3(HITP)2 in 1 M tetraethylammonium bis(trifluoromethylsulfonyl)imide (NEt4TFSI) in acetonitrile electrolyte. The same two anion environments were evident in the spectrum, but with a measured Δδ for the 'in-pore' environment of +2.1 ppm (Figure , SI Table ). Hence, these nucleus and anion-dependent results therefore demonstrate ring-current effects, whilst perhaps a contributor, are not dominant for this system, leading to a hypothesis that non-covalent interactions dominate the observed shifts. We further propose that the Δδ value is related to the strength of the interaction between the anions and the MOF functionality. DFT calculations confirmed a larger charge density on the fluorine atoms for the BF4 - anion compared to the TFSI -anion as expected, leading to a stronger specific interaction alongside a larger observed Δδ. Additionally, B NMR above gave rise to a low Δδ of just +0.7 ppm as boron, unlike fluorine, is not directly participating in a specific interaction with the MOF pore wall. These experimental therefore results support the hypothesis that the MOF-electrolyte interaction strength is modulated by the charge density on the fluorine (SI Figure ).