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A combination of Schwesinger's phosphazene base concept and the idea of the disubstitued 1,8-naphthalene spacer, yields a superbase, 1,8-bis(hexamethyltriaminophosphazenyl)naphhalene (HMPN), which is the most basic representative of 'proton sponges'. The high basicity of HMPN is a consequence of the high energy content of the base in its initial neutral state and the intramolecular hydrogen bonding in the resulting conjugate acid with contributions to proton affinity.

Gas-phase H/D exchange experiments with CD3OD and D2O and quantum chemical ab initio G3(MP2) calculations is conducted on protonated histidine and protonated histidine methyl ester in order to elucidate their bonding and structure. Results reveal that the proton fluctuates between the amino and imidazole groups in the protonated form across an almost vanishing barrier.

Results reveal that polyguanidines exhibit very high proton affinities with the linear chain poly-guanides saturation effect depending on the number of guanidine units. A doubly bifurcated heptaguanide shows the largest proton affinity caused by substantial resonance effect of the protonation.

Influence of fluorine substitutions on the stability of benzene is examined by using the Hartree-Fock (HF) and MP2 models. The homodesmotic reactions based on the open-chain zigzag polyenes are unsatisfactory and the result implies that both sigma- and pi-frameworks contribute to the aromatic stabilization of benzene in which the latter is more important.

The extrinsic antiaromaticity of archetypal cyclobutadiene (CBD) is addressed with particular emphasis on the alpha-pi separability problem. The study found that the one-electron MO picture cannot offer a satisfactory description of antiaromaticity, since both the alpha-MOs and pi-MOs energies contribute to E (d)(sub CBD) with an overwhelming influence of the alpha electrons.

The characterization of dimethylethyleneguanidino (DMEGN) reveals an unsymmetrical intramolecular hydrogen bridge. It is stated that, a new proton sponge provides a new crossbar in the ladder of highly basic neutral organic compounds.

The article discusses recent advancement in determination of absolute proton affinities which is measure of gas-phase basicity of neutral organic molecules. The measurement of proton affinities has been performed by computational chemistry studies of organic molecules. It also highlights importance of determination of proton affinity which forms smallest and lightest part of atomic nucleus with its significant role in chemistry, biochemistry and molecular biology.