We report high-level electronic structure calculations of electronic states in the miniSOG (for mini Singlet Oxygen Generator) photoactive protein designed to produce singlet oxygen upon light exposure. We consider a model system with a riboflavin (RF) chromophore. To better understand the photosensitization process, we compute relevant electronic states of the combined oxygen-chromophore system and their couplings. The calculations suggest that singlet oxygen can be produced both by inter-system crossing, via a triplet state of the RF(T1)×O2(3Σ− g ) character as well as by triplet excitation energy transfer via a singlet state of the same character. Importantly, the former channel produces O2(1Σ+ g ), an excited state of singlet oxygen, which is known to convert with unit efficiency into O2(1∆g) The calculations also provide evidence for the production of the triplet state of the chromophore via internal conversion facilitated by oxygen. Our results provide concrete support to previously hypothesized scenarios.
This content will become publicly available on March 28, 2025
- Award ID(s):
- 2154482
- NSF-PAR ID:
- 10522709
- Publisher / Repository:
- J. Chem. Phys.
- Date Published:
- Journal Name:
- The Journal of Chemical Physics
- Volume:
- 160
- Issue:
- 12
- ISSN:
- 0021-9606
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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