Imidazolium p-tert-Butylthiacalix[4]arene Amphiphiles-Aggregation in Water Solutions and Binding with Adenosine 5 '-Triphosphate Dipotassium Salt

Aggregation properties of water-soluble cationic amphiphilic p-tert-butylthiacalix[4]arene derivatives adopting 1,3-alternate stereoisomeric form with methylimidazolyl headgroups were studied. It was found that derivatives 1 and 2 form stable aggregates in water solutions. The size and shape of aggregates were defined using DLS and TEM techniques. Critical aggregation concentration (CAC) of methylimidazolyl derivatives was calculated using dye micellization method. It was found that correct CAC determination of cationic amphiphiles using anionic xanthene dyes should be considered carefully in respect with electrostatic interactions. Using indicator displacement procedure, DLS studies, and P-31 NMR spectroscopy, it was found that macrocycles 1 and 2 bind with ATP with 1:1 stoichiometry. It was found that ATP causes eosin Y release from binary thiacalixarene-eosin Y system up from 3 to 12 mu M of ATP in the case of macrocycles 1 and 2, respectively.