Extraction and DFT Study on the Complexation of the TRIS+ Cation with a Hexaarylbenzene-Based Receptor

From extraction experiments and -activity measurements, the exchange extraction constant corresponding to the equilibrium TRIS+(aq) + 1.Cs+(nb) <-> 1.TRIS+(nb) + Cs+(aq) taking place in the two-phase water-nitrobenzene system (TRIS+ = (HOCH2)3C-NH3+, 1 = hexaarylbenzene - based receptor; aq = aqueous phase, nb = nitrobenzene phase) was evaluated as log Kex (TRIS+, 1.Cs+) = -2.0 ± 0.1. Further, the stability constant of the hexaarylbenzene - based receptor .TRIS+ complex (abbrev. 1.TRIS+) in nitrobenzene saturated with water was calculated for a temperature of 25 °C : log βnb (1.TRIS+) = 6.0 ± 0.2. By using quantum mechanical calculations, the most probable structure of the 1.TRIS+ complex species was solved. In this complex having C3 symmetry, the cation TRIS+ synergistically interacts with the polar ethereal oxygen fence and with the central hydrophobic benzene bottom via cation - π interaction.