Fig. 5.

Species corresponding to the assigned ESI-MS peaks obtained after mixing the alkyne with the ligand [Tr,Tr,Tr] 1, 2, 4 or 5, and CuSO₄/Na-ascorbate. * and ** were formed by adventitious oxidation of the OEG side chain in the alkyne or the ligand during sample introduction to the ESI-MS. ESI-MS spectra of the Cu(I)-ligand-alkyne 1:1:0.5 mixture in water. CuSO₄ (100 µM), ligand (100 µM), PE (50 µM), Na ascorbate (1 mM). (A) Ligand 1. (B) Ligand 2. (C) Ligand 4. (D) Ligand 5.