Dramatic expansion of bimodal redox window of indigo by two-electron redox processes.
basic_science · Level V
Where this comes from
- Record sourced from PubMed, PMID 41402281.
- Also identified by DOI 10.1038/s41467-025-66186-w and PMC identifier 12738839.
- Licence recorded as CC BY-NC-ND.
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Abstract
Indigo is an extremely popular molecule in dye industry, however, its use in photochemical transformations is surprisingly scarce. This report explores its photocatalytic activity over an unusually wide excited-state redox window, spanning over 5.98 V. The dye molecule exhibits bimodality and proves itself as a simultaneous super-reductant and -oxidant. This extreme bimodal behavior in indigo (IndH<sub>2</sub>) originates from the viability of two electron redox processes on the parent architecture. In comparison, major popular photocatalysts (PC) possess singly oxidized/reduced state, limiting the span of such bimodal redox window significantly. In the presence of KO<sup>t</sup>Bu and white light irradiation, IndH<sub>2</sub> is converted to its tetraanionic form Ind<sup>4-</sup> by two-electron reduction and two successive deprotonation steps, exhibiting its reductive power to -3.6 V vs SCE. On the other hand, two-electron oxidized form of IndH<sub>2</sub> forms dehydroindigo, a superoxidant capable of oxidizing substrates up to +2.38 V vs SCE.