Photochemistry and photophysics of halogen-substituted dibenzothiophene oxides.
Dibenzothiophene-5-oxide (DBTO) cleanly produces dibenzothiophene (DBT) on direct photolysis, but with very low quantum yield. A proposed mechanism involves scission of the S-O bond which is coupled to an intersystem crossing step, thus producing the sulfide and O((3)P) via a unimolecular pathway. To test this hypothesis, heavy atom substituted DBTOs were prepared and photolyzed. Iodo-, bromo-, and chloro-substituted DBTOs show higher quantum yields for deoxygenation than does the parent molecule, in the order consistent with an intersystem crossing-related heavy atom effect. 2-Iododibenzothiophene also undergoes photochemical deiodination. Phosphorescence data are consistent with heavy-atom assisted intersystem crossing.
Nag
Mrinmoy
M
Department of Chemistry, Iowa State University, Ames, Iowa 50011, USA.
Jenks
William S
WS
D006219:Halogens / Q000737:chemistry*; D015394:Molecular Structure; D010777:Photochemistry; D010782:Photolysis; D013876:Thiophenes / Q000138:chemical synthesis* / Q000737:chemistry* / Q000528:radiation effects; D014466:Ultraviolet Rays
D006219:Halogens; D013876:Thiophenes; C058517:dibenzothiophene 5-oxide; C016366:dibenzothiophene