For the bicarbonate clusters, carbonyl oxygens are clearly distinguished at high δ iso = 174-209 ppm, above that of hydroxyl oxygens at δ iso = 125-145 ppm and water δ iso = -4 to -34 ppm (Fig. ). Additionally, the C Q values of hydroxyl oxygens are found to be higher, C Q = 9-9.6 MHz, than for carbonyls, C Q = 7-8.1 MHz. Comparison to the MOF structures also corroborates these trends with the hydroxyl matching in all three NMR parameters. The carbonyl's are more spread for MFU-4l with respect to δ iso , though C Q remains in agreement. This is due to polarisation induced by the Zn-metal centre, whereas the CD-MOF remains in agreement with the clusters in both δ iso and C Q as no metal-bicarbonate bond is present.