Synthesis and characterisation. To study conductive layered metal-organic framework supercapacitors with NMR spectroscopy, nickel 2,3,6,7,10,11-hexaiminotriphenylene, Ni3(HITP)2, was selected as it had already been reported to have good supercapacitor performance, and had been used in both experimental and computational studies of supercapacitor charging mechanisms (Figure ). In this MOF, the Ni 2+ sites are spd2 hybridised in a square planar configuration, with the resulting low-spin, diamagnetic electronic configuration on the metal site avoiding potential paramagnetic NMR effects caused by the metal centre. The syntheses in this work were based on that previously reported by Sheberla et al., and in each case successful synthesis of crystalline Ni3(HITP)2 was confirmed by powder X-Ray Diffraction (PXRD), with inspection of the diffraction angle of the peaks indicating a consistent crystallographic pore size for all samples (SI Figure ). The samples were subsequently characterised by 77 K N2 sorption isotherms (SI Figure ), and despite a consistent synthetic procedure, a range of Brunauer-Emmett-Teller (BET) specific surface areas (SSAs) were calculated for the six samples labelled A-F, ranging from 309-894 m 2 g -1 (SI Figure , SI Table ). These values are consistent with the range previously reported for this MOF in the literature (260-885 m 2 g -1 ). We note that even our best samples (samples A and F at 852 and 894 m 2 g -1 ) have significantly lower BET SSAs than the reported theoretical value of 1370 m 2 g -1 for this MOF, indicating a significant potential for pore blockages from impurities or sample defects. Scanning electron microscopy (SEM) of selected samples confirmed the expected rod-like morphology of the particles (SI Figure ). Microanalysis highlighted some deviation from the expected stoichiometric quantities of elements, indicating varying levels of defects and impurities in the samples with the additional presence of some chlorine impurities from the starting materials, as previously reported by Sun et al. (SI Table ). After characterising the synthesised Ni3(HITP)2 samples for their crystallinity, porosity, microstructure and chemical composition, the samples were employed in subsequent NMR studies. Unless otherwise specified, results reported below are from samples with a measured BET SSA within 5 % of the highest reported BET SSA in the literature and thus considered to be the highest quality samples.