The broad tunability of the diamine-M 2 (dobpdc) family of materials and large number of available DFT-calculated adsorption structures presented an excellent opportunity to explore NMR parameters for differentiating CO 2 adsorption products. To increase the diversity of structures explored, for select materials we explored not only the leading candidate adsorption product from previous studies, but also the other adsorption products in Figure (see Table for a list of studied materials). While C NMR spectroscopy is the most commonly used tool for probing CO 2 adsorption products, our DFT calculations show that poor differentiation of ammonium carbamate and carbamic acid binding modes is achieved by the C chemical shifts (Figure ,b, Table ). Better differentiation of products is achieved by considering the orientation dependence of the C chemical shift (i.e., the chemical shift anisotropy), consistent with recent work on amine-functionalised silicas. However, in many cases carbamic acid and ammonium carbamate species still have similar C NMR parameters (Figure ) because both the protonation state (ammonium carbamate chain or carbamic acid) and other hydrogen bonding interactions have an impact. These findings support the idea that alternative NMR probes beyond C are needed to characterise CO 2 adsorption modes with greater confidence.