In summary, we have developed a modular approach to the synthesis of diazabicyclic amides and anilines, in which a calculated values (DMSO solvation); b unambiguous assignment not possible independent variation of the ring sizes allows interrogation of the effect on molecular structures and properties. The ability to tune molecular properties (e.g. pK a ) by variation of scaffold size rather than substituents or functional groups may find application in the design of functional organic molecules.