2 Results and Discussion Investigating CO 2 capture by hydroxides through O NMR spectroscopy requires the establishment of the expected range of quadrupolar NMR parameters for the predicted products of capture, i.e. bicarbonate and carbonate. Representative hydrated anion clusters of bicarbonate (Fig. ) and carbonate (Fig. -F) were generated using static DFT calculations in line with those previously reported in the literature (see Figs. S1-S2 for full structure list). These structures were identified as the most general candidate structures with their diversity of hydrogen-bonded oxygen environments hypothesised to represent the likely environments found in the binding sites of solidstate CO 2 sorbents. For comparative purposes, calculated NMR parameters for periodic boundary condition structures of bound CO 2 in KHCO 3 CD-MOF (Fig. ) and two modes proposed for MFU-4l (Fig. ) are also included in Fig. .