Strategic design of small and versatile bicyclic organic superbases: a density functional study

It is shown by a reliable DFT method that bicyclic structures 7–10, constructed using 1,3-diaminopropane as an essential building block, can act as powerful neutral organic superbases in the gas phase, aqueous solution and in acetonitrile. This new molecular framework is versatile in terms of anchoring different functional groups to achieve higher basicities. The buttressing effect of substituents on the basicity of these organic bases was also observed. The proton affinities calculated at the B3LYP/6-311+G**//B3LYP/6-31+G* level for 1,2-diaminoethane and 1,3-diaminopropane were found to be in good agreement with the experimental results. Barriers for proton transfer between the N atoms of the diamine and diimine cations are also reported.