Cu(II)-selective fluorescence of a bis-quinolylimine derivative

A new bis-quinolylimine ligand containing an azadiene moiety, 1,4-bis(2-quinolyl)-2,3-diaza-1,3-buthadiene (1), was synthesized by one-step facile condensation. This simple ligand, when dissolved in acetonitrile, shows a Cu2+-selective fluorescence enhancement. Coordination of 1 with Cu2+ produces two kinds of complexes with 1:1 and 1:2 stoichiometries. The 1:2 complex shows a strong fluorescence (ΦF = 0.37), while the 1:1 complex does not (ΦF