Fig. 3.

Performance of the 21 ligands (1–21) of Cu⁺. (A) Apparent second-order rate constant (k_obs) for the reaction of azido-coumarin AC (100 µM) with propargyl alcohol (50 µM) in the presence of the ligand (100 µM), CuSO₄ (100 µM), and sodium ascorbate (5 mM) in phosphate buffered saline (PBS, pH = 7.4) in air at 24 ± 1 °C during 60 min.^57–60 (B) The initial air-oxidation rate (V_o) of sodium ascorbate (200 µM) by diffused O₂ in the presence of ligand/Cu(I) 1:1 complexes (100 µM) in PBS (pH = 7.4) at 24 ± 1 °C. (C) Dissociation constants of the Cu(I)-ligand complexes measured by competitive binding assay with Bca. (D) The trade-off between CuAAC over oxidation (k_obs/V_o). (E) The trade-off between CuAAC over dissociation constants (k_obs/K_D). Error bars represent the standard deviation from three-repeated measurement. [m,n,o] represents the chelate arm length. Me in [m,n,o-Me] represents the methyl substitution on the methylene group between central amine and phenyl arm, for 13, 15, 18–21. Me2 in [m,n,o-Me2] represents the methyl substitutions on the 6-position of pyridyl arms, for 14 and 16.