The polyaromatic terdentate ligand 6-(azaindol-1-yl)-2,2'-bipyridine (L7) combines one 5-membered chelate ring with a fused 6-membered chelate ring. It is designed to provide complexation properties intermediate between 2,2';6',2 ''-terpyridine (L1) (two fused 5-membered chelate rings) and 2,6-bis(azaindol-1-yl)pyridine (L6) (two fused 6-membered chelate rings). In polar organic solvents, L7 displays remarkable affinities for the successive fixation of two small univalent cations M = H+ or Li+, leading to stable [M-m(L7)](m+) (m = 1-2) complexes. Upon reaction with M = Mg2+ or Zn2+ cations, the large positive charge densities borne by the metals result in the successive cooperative complexation of two ligands to give [M(L7)](n+) (n = 1-2). For small Sc3+, unavoidable traces of water favor the formation of the protonated ligand at millimolar concentrations in acetonitrile, but the use of larger Y3+ cations leads to [Y(L7)](n+) (n = 1, 2), for which stability constants of log(beta(Y,L7)(1,1)) = 2.9(5) and log(beta(Y,L7)(1,2)) = 5.3(4) are estimated The complexation behaviors are supported by speciations in solution, thermodynamic analyses, and solution and solid-state structures