Photodeoxygenation of dinaphthothiophene, benzophenanthrothiophene, and benzonaphthothiophene -oxides

• Published in: Photochemical & photobiological sciences 2016-06, Vol.15 (6), p.791-8
• Main Authors: Zheng, X, Baumann, S. M, Chintala, S. M, Galloway, K. D, Slaughter, J. B, McCulla, R. D
• Format: Article
• ISSN: 1474-905X; 1474-9092
• DOI: 10.1039/c5pp00466g

Photoinduced deoxygenation of dibenzothiophene S -oxide (DBTO) has been suggested to release atomic oxygen [O( 3 P)]. To expand the conditions and applications where O( 3 P) could be used, generation of O( 3 P) at longer wavelengths was desirable. The sulfoxides benzo[ b ]naphtho-[1,2, d ]thiophene S -oxide, benzo[ b ]naphtho[2,1, d ]thiophene S -oxide, benzo[ b ]phenanthro[9,10- d ]thiophene S -oxide, dinaphtho[2,1- b :1′,2′- d ]thiophene S -oxide, and dinaphtho[1,2- b :2′,1′- d ]thiophene S -oxide all absorb light at longer wavelengths than DBTO. To determine if these sulfoxides could be used to generate O( 3 P), quantum yield studies, product studies, and computational analysis were performed. Quantum yields for the deoxygenation were up to 3 times larger for these sulfoxides compared to DBTO. However, oxidation of the solvent by these sulfoxides resulted in different ratios of oxidized products compared to DBTO, which suggested a change in deoxygenation mechanism. Density functional calculations revealed a much larger singlet-triplet gap for the larger sulfoxides compared to DBTO. This led to the conclusion that the examined sulfoxides could undergo deoxygenation by two different mechanisms. The benzannulation of dibenzothiophene S -oxide to extend the photorelease of atomic oxygen to longer wavelengths.