Synthesis and fluorescence of a configurationally locked Z-hexatriene: 1,2-divinylcyclopentene

• Published in: Tetrahedron Vol. 49; no. 27; pp. 6045 - 6052
• Main Authors: Wolde, Annemarie ten, Dekkers, Harry P.J.M., Jacobs, Harry J.C.
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier Ltd 02.07.1993; Elsevier
• Subjects: Alicyclic compounds; Alicyclic compounds, terpenoids, prostaglandins, steroids; Chemistry; Exact sciences and technology; Organic chemistry; Preparations and properties; Fluorescence spectrum; Conjugated polyenic compound; Trienic compound; Cyclization; Aliphatic compound; Haloester; Overhauser effect; Ultraviolet spectrum; NMR spectrum; Monocyclic compound; Conformation
• ISSN: 0040-4020; 1464-5416
• DOI: 10.1016/S0040-4020(01)87189-1

The syntheses of the configurationally locked Z-hexatriene, 1,2-divinylcyclopentene, and its terminally tetradeuterated isotopomer are described, and some photochemical and photophysical properties are reported. The trienes turn out to be photostable under oxygen-free conditions. In contrast to “unlocked” hexatrienes, both compounds fluoresce (room temperature, methanol). The fluorescence is structured and is the nearly perfect mirror image of the absorption band, with a small Stokes shift. Therefore the emission might originate in the 1 1B 1 state. This is the first observation of fluorescence of simple hexatrienes in solution. Apparently torsional motion around the central (originally double) bond in the excited singlet state is an important radiationless deactivation pathway in “unlocked” hexatrienes; if it is obstructed fluorescence becomes a passable deactivation pathway. The syntheses and fluorescence of the trienes 1,2-divinylcyclopentene and its terminally tetradeuterated isotopomer are reported.