Synthesis and photophysical properties of conjugated thioketone, thioketone S-oxide (Sulfine), and related compounds incorporated in a dibenzobarrelene skeleton. (3rd May 2020)

• Record Type: Journal Article
• Authors: Ishii, Akihiko; Ebina, Ryota; Shibata, Mari; Hayashi, Yuki; Nakata, Norio
• Is Part Of: Journal of sulfur chemistry. Volume 41:Number 3(2020)
• Page Start: 238
• Page End: 257
• Publication Date: 2020-05-03
• Subjects: Conjugated thioketone -- conjugated sulfine -- X-ray crystallography -- isomerization -- photoisomerization -- fluorescence; Sulfur -- Periodicals; Chemistry, Inorganic -- Periodicals; 546.72305
• DOI: 10.1080/17415993.2020.1727905
• Languages: English
• ISSNs: 1741-5993

Abstract

ABSTRACT: Conjugated thioketone and thioketone S -oxide (sulfine) were synthesized from the corresponding ketone conjugated to a 1, 3-butadiene system incorporated in a dibenzobarrelene skeleton. The conjugated thioketone was obtained by the reaction of the corresponding diazo compound with elemental sulfur, the oxidation of which with m -chloroperoxybenzoic acid provided the conjugated sulfine as a mixture of ( Z )- and ( E )-stereoisomers. ( E )-Sulfine gradually isomerized to ( Z )-sulfine in solution in the dark. Photoisomerization between ( Z )- and ( E )-sulfines was observed under photoirradiation together with the desulfurization to the corresponding ketone. The conjugated thioketone showed the weak long-wavelength absorption at 626 nm due to the n-π* excitation in the optical absorption spectrum and nonphotoluminescent. The conjugated ( Z )-sulfine exhibited the long-wavelength absorption at 448 nm due to the π-π* excitation and very weak photoluminescence at 489 nm with the quantum yield of 0.002 at room temperature. The weak photoluminescence was enhanced in EtOH at 77 K showing yellow luminescence, and the quantum yield increased to 0.32. Lifetime values of the luminescence (2.4 and 6.8 ns) at 77 K suggests that the luminescence is fluorescence. A large solvent effect and a similar temperature dependency of photoluminescence were observed for the conjugated ketone. GRAPHICAL ABSTRACT: