MOFs are a class of microporous materials typically constructed from metal nodes and organic linkers to give three-dimensional framework structures. Their use as CO2 sorbents is highly favourable owing to their high surface areas and the possibility to precisely control the pore chemistry. One emerging class of MOFs that have shown promise for CO2 capture are amine-appended frameworks based on the MOF-74 structure, such as M2(dobpdc) where M = Mg, Mn, Fe, Co, Ni, Cu, Zn, Cd, and dobpdc = 4,4′-dioxidobiphenyl-3,3′-dicarboxylate (Figure ). In this structure, the metal ion has a vacant coordination site along the microporous channels. The appendage of an organic amine compound to these vacant metal sites (Figure ) gives rise to large adsorption capacities for selective and reversible CO2 uptake. As the nature of both the metal cation and the amine can be varied, the adsorption thermodynamics can be tuned for a desired application. 12, Amine-appended MOF-74 analogues may be advantageous over other sorbent materials, as they display step-shaped adsorption isotherms, suggesting that CO2 uptake/release is sudden upon exposure at a threshold pressure. As such, these materials have lower regeneration energies than traditional amine scrubbing technologies. Basic characterisation methods such as powder X-ray diffraction and solution state 1 H NMR of digested frameworks can be used in order to ascertain the long-range ordering of the material and to assess the amine loading, respectively. In these materials a 1:1 metal:amine ratio can be achieved, indicating that all initially vacant metal sites are occupied by amines (Figure ). X-ray crystallography studies on large single crystals of amine-appended-Zn2(dobpdc) materials have shown that at least two types of CO2 adsorption products can be formed in these materials. The first product is ammonium carbamate chains, where CO2 inserts itself into the Metal-N bond to form a negatively charged carbamate (Figure ) and a neighbouring diamine forms a positive ammonium. Adjacent carbamates and ammoniums form ion pairing and hydrogen bonding interactions to produce chains, explain the cooperative adsorption in these materials, and accounting for the step-shaped adsorption isotherms. The ammonium carbamate chain product has been observed for many diamine-Zn2(dobpdc) analogues, and is thought to be the most prevalent product. In (dmpn)2-Zn2(dobpdc) (dmpn = 2,2-dimethyl-1,3-diaminopropane), however, the formation of carbamic acid pairs was reported, whereby the CO2 molecule reacts with a "dangling" primary amine, and two carbamic acids interact via hydrogen bonding to form a pair (Figure ). Unfortunately, structure solution by X-ray crystallography generally requires large single crystals which are difficult to synthesise for many analogues of M2(dobpdc). The case studies presented here use multinuclear NMR spectroscopy to explore CO2 adsorption on the molecular level without the need for large single crystals and can, therefore, be applied to many different amine analogues in these MOFs. Indeed, we will show how solid-state NMR studies on (dmpn)2-Mg2(dobpdc) materials revealed that CO2 can adsorb by a third mechanism where both ammonium carbonate chains and carbamic acids are formed on adjacent metal sites, stabilised by hydrogen bonding (Figure ). Case Study 1: Elucidating Chemisorption in MOFs with