Oxygen-aromatic interactions

Fig. 11. Diagrammatic view of contacts between ethacrynic acid and deoxyhemoglobin A. The ligand is covalently bound to cysteine-93 of the p chain. and indicate fractional charges due to the electronic dipolar nature of the o-dichlorobenzene moiety. Broken lines indicate hydrogen bonds and dotted lines van der Waals contacts. Oxygen-aromatic interactions involving aspartate-94 and cysteine-93 are shown schematically. Reproduced with permission from Perutz et al. (1986).

Fig. 14. Nicotinamide-binding site of Lactobacillus casei dihydrofolate reductase. NADPH is indicated by its van der Waals surface. The oxygen atoms of isoleucin-12, threonine-45, and alanine-97 that are involved in enthalpically favorable oxygen-aromatic interactions with NADPH are labeled.

A number of photophysical studies have been reported concerning the interactions of ground state amines with dyes. Foote (28) first suggested that dye triplets could interact with oxygen to yield singlet oxygen. Similar interaction of dye triplets with aromatic amines can lead to dye quenching via electron transfer (29-31). 

Desiraju, G. R. and Jagarlapudi, A. R. P., C-HLO interactions and the adoption of a 4 A short axis crystal structure by oxygenated aromatic compounds, J. Chem. Soc. Perkin Trans. 2, 1195, 1987. 

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