Complexes of Ag+ with mixed donor phenanthroline-containing macrocycles: spectrofluorimetric, spectrophotometric, conductometric and potentiometric studies

The reactions of Ag+ with five mixed donor phenanthroline-containing macrocycles (L1–L5) having N2S3-, N2S2O-, N2S2-, N3S2-, and N4S2-donor sets, respectively, have been studied in MeCN by spectrofluorimetric, spectrophotometric, conductometric and potentiometric methods. All ligands form 1:1 [Ag(L)]+ complexes, and in the case of L4 and L5, formation of 1:2 [Ag(L)2]+ species is also observed. The corresponding formation constants have been evaluated and their values allow a deeper insight into the role played by complexation process in the potentiometric selectivity for Ag+ of membrane electrodes (ISE), and in the selective transport of Ag+ through supported liquid membrane (SLM) systems based on these ligands. The X-ray crystal structure of the complex [Ag(L4)]BF4 is also reported.