Spectral and Photophysical Properties of Thioxanthone in Protic and Aprotic Solvents: The Role of Hydrogen Bonds in S1-Thioxanthone Deactivation

✍ Scribed by Ewa Krystkowiak; Andrzej Maciejewski; Jacek Kubicki

• Publisher: John Wiley and Sons
• Year: 2006
• Tongue: English
• Weight: 195 KB
• Volume: 7
• Category: Article
• ISSN: 1439-4235
• DOI: 10.1002/cphc.200500375

✦ Synopsis

Abstract

Spectral and photophysical properties of thioxanthone (9__H__‐thioxanthen‐9‐one, TX) were determined in a few protic solvents (H~2~O, D~2~O, hexafluoro‐2‐propanol) and compared with those in aprotic solvents. On the basis of the time‐resolved and steady‐state emission measurements and available literature data, it has been shown that the dominant S~1~‐TX deactivation process in protic solvents is the formation of the S~1~‐complex. The important modes of deactivation of the S~1~‐complex are fluorescence (ϕ~F~≈0.4–0.5) and intersystem crossing to the T~1~ state. The S~1~‐complex→S~0~ internal conversion plays, at most, an insignificant role in S~1~‐complex deactivation, which is evidenced by the absence of an isotope effect of protic solvents on the lifetime and quantum yield of fluorescence.