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Spectrofluorimetric study on the inclusion behavior of p-sulfonated calix [4, 6, 8] arene with cocaine hydrochloride

Qian Du, Cai-Ping Chen, Li-Ming Du

The characteristics of host–guest complexations between p-sulfonated calix[n]arenes (n = 4, 6, 8) and Cocaine hydrochloride have been studied through fluorescence and 1H NMR spectroscopic. It was found that the fluorescence intensity of Cocaine hydrochloride quenched regularly upon the addition of p-sulfonated calix[n]arenes (n = 4, 6, 8).A1:1 stoichiometry for the complexation was established and was verified by Job’s plot. The temperature-dependent inclusion constants were calculated. Meanwhile, the proposed interactionmechanismof the inclusion complexwas discussed based on 1H NMR and molecular modeling calculations. The various factors (pH, ionic strength, concentration, temperature, the addition order of reagents, reaction time, surfactants) effecting the inclusion process were examined in detail.