THE DETERMINATION OF COMPLEX STABILITIES WITH NEARLY INSOLUBLE HOST MOLECULES - COMPLEXATION OF SOME TRANSITION AND HEAVY-METAL CATIONS WITH DIBENZO-18-CROWN-6 IN AQUEOUS-SOLUTION

Complex formation between dibenzo-18-crown-6 and Pb2+, Tl+, Ag+, Co2+, Ni2+ and Cu2+ was studied by a new spectrophotometric method in aqueo us solution. Due to complex formation the concentration of the ligand increases in solution. This can be detected spectrophotometrically. Fr om the increases in solubility of dibenzo-18-crown-6 in the presence o f salts, the stability constants of the complexes formed can be calcul ated. If the cation and/or the anion have an absorptivity at the same wavelength as the ligand, solutions with an identical concentration of the salt have to be used as reference. (C) 1998 Elsevier Science S.A. All rights reserved.