摘要
Copper(I) quantum yields are reported for Cu(II) complexes of aliphatic dicarboxylates in aqueous solution (N2-purged), based on steady-state illuminations. For Cu(dicarboxylate)0, the Cu(I) quantum yields at 313 nm (ΦCu(I),CuL) exhibit the following trend (25 °C, ionic strength = 0.10 M): malonate (0.15 ± 0.07) > succinate (0.10 ± 0.02) (Sun, L.; Wu, C.-H.; Faust, B. C. J. Phys. Chem. A 1998, 102, 8664−8672) > glutarate (0.054 ± 0.005) > adipate (0.042 ± 0.004) ≈ pimelate (0.046 ± 0.009). The systematic decrease in Cu(I) quantum yield observed for these Cu(dicarboxylate)0 complexes parallels the increasing degree of outer-sphere coordination of the complexes. Free uncomplexed malonate species quench the photoformation of Cu(I) from Cu(malonate)0 in a way that cannot be explained solely based on the Cu(II) speciation. An interpretation based on the quenching of the intermediate [Cu(·CH2C(O)O-)0] by H(malonate)-/H2(malonate)0 is proposed. Evidence is presented for Cu(I) photoformation from Cu(malonate)0.