We investigated the chemistry of singlet oxygen with a cadmium-sulfur cluster, (Me 4 N) 2 [Cd 4 (SPh) 10 ]. This cluster was used as a model for cadmium-sulfur nanoparticles. Such nanoparticles are often used in conjunction with photosensitizers (for singlet oxygen generation or dye-sensitized solar cells), and hence, it is important to determine if cadmium-sulfur moieties physically quench and/or chemically react with singlet oxygen. We found that (Me 4 N) 2 [Cd 4 (SPh) 10 ] is indeed a very strong quencher of singlet oxygen with total rate constants for 1 O 2 removal of (5.8 ± 1.3) × 10 8 M -1 s -1 in acetonitrile and (1.2 ± 0.5) × 10 8 M -1 s -1 in CD 3 OD. Physical quenching predominates, but chemical reaction leading to decomposition of the cluster and formation of sulfinate is also significant, with a rate constant of (4.1 ± 0.6) × 10 6 M -1 s -1 in methanol. Commercially available cadmium-sulfur quantum dots ("lumidots") show similar singlet oxygen quenching rate constants, based on the molar concentration of the quantum dots.
All Science Journal Classification (ASJC) codes
- Colloid and Surface Chemistry