The Influence of 2,2′-Bipyridine and 1-Amino-9,10-anthraquinone Side-Arm on Complexation Equilibria of Diaza-15-crown Ether in Various Solvents

The influence of 2,2'-bipyridine and 1-amino-9,10-anthraquinone side-arm of diaza-15-crown ether on silver(I) complexation equilibria has been investigated in various non-aqueous solvents. The 2,2'-bipyridyl residue attached to the nitrogen atom of the macrocycle significantly controls the formation of 1: 1 inclusion-type complexes by stabilizing silver ions inside the cavity. The addition of a second 2,2'-bipyridine or 1-amino-9,10-anthraquinone slightly changes the stability constants of diaza-15-crown ether complexes and as well 1:2 metal-to-ligand complexes. Ag2L22+, Ag2L32+ and Ag2L32+ have been found, depending on the type of ligand and solvent species of higher complexity. This has been proved by both spectrophotometric and potentiometric methods. Studies of substituted diaza-15-crown ethers were performed for comparison with an unsubstituted ligand.