Light Induced Redox Reactions of Water Soluble Porphyrins, sensitization of hydrogen generation from water by zincporphyrin derivatives
✍ Scribed by Kuppuswamy Kalyanasundaram; Michael Grätzel
- Publisher
- John Wiley and Sons
- Year
- 1980
- Tongue
- German
- Weight
- 442 KB
- Volume
- 63
- Category
- Article
- ISSN
- 0018-019X
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✦ Synopsis
Abstract
The photoredox behaviour of two water soluble derivatives of zincporphyrin, 5,10,15,20‐tetra‐p‐sulfonatophenyl (1) and 5,10,15,20‐tetra‐p‐N‐methylpyridiniochloride (2), was investigated using laser and continuous photolysis techniques. Photoexcitation produces triplet states whose lifetimes in aqueous solution exceeds 1 ms. These triplet states can be quenched reductively by donors such as EDTA and oxidatively by acceptors such as methylviologen (MV^2+^). Electron transfer to MV^2+^ is greatly influenced by the charge of the porphyrin, rate constants being 1.4 x 10^10^M^−1^S^−1^ and 2 × 10^6^M^−1^S^−1^ for 1 and 2, respectively. In the presence of colloidal Pt catalyst, the cationic porphyrin sensitizes photoreduction of water to hydrogen with remarkable efficiency.