Complex formation in Aerosol OT reversed micelles between sodium counterion and Kryptofix 221D macrobicyclic ligand

The interaction between 5-decyl-4,7,13,16,21-pentaoxa-1,10-diazabicyclo-[8,8,5]-tricosan (Kryptofix 221D) and reversed micelles of sodium bis(2-ethylhexyl) sulfosuccinate (AOT) in n-heptane as a function of AOT and water concentration was investigated by a calorimetric technique. The solubilization of the cryptand in the reversed AOT micelles produces an exothermic effect that increases with R (R=[water]/[AOT]) and is slightly dependent on AOT concentration. Processes due to the formation of a 1:1 complex between the cryptand and the sodium counterion of the AOT and to the transfer of Kryptofix 221D from bulk n-heptane to the micellar palisade layer have been taken into account to rationalize the experimental results. The peculiar solvation state of the sodium counterions near the water-AOT interface has also been considered.In part from the Doctor in Biology thesis of F. Pinio in the University of Palermo.