To further investigate the proposed specific MOF-electrolyte interactions, chemical shift calculations were carried out on structural fragments extracted from hybrid QM/MM simulations of the Ni3(HITP)2 -NEt4BF4/ACN system (see SI and SI Figure for details). The simulations predicted respective F and B NMR Δδ values of +3.4 ppm and +1.1 ppm calculated for a BF4 -anion in close proximity to a MOF fragment, compared to an anion in bulk acetonitrile (Figure , e, SI Table ), in close agreement with the experimental values. Furthermore, simulations in the absence of an applied electrochemical potential, show that the anions are distributed over a range of sites within the pore, but overall favour sites close to the MOF pore walls, adjacent to the N-H groups (SI Figure ). Collectively, these results support the hypothesis that the F and B chemical shifts arise predominantly from a hydrogen-bond type interaction of the fluorine atoms with the hydrogens in the MOF N-H groups and that the value of Δδ may be linked to the strength of that interaction. It is these specific interactions which are responsible for the high resolution of the in-pore environment in the F NMR. Thus, anions closer to the centre of the MOF pore would have a lower Δδ if measured directly, but as they are in fast exchange with the anions on the edge of the pores, the observed Δδ is a weighted average of all the anion environments. This specific anion-MOF specific interaction may also explain why the same effect is not seen in the 1 H NMR spectra of the electrolyte cations, which will not undergo the same favourable hydrogen-bonding interaction with the MOF (SI Figure ).