title: Spectral and photophysical properties of thioxanthone in protic and aprotic solvents: the role of hydrogen bonds in S1-thioxanthone deactivation.
abstract: Spectral and photophysical properties of thioxanthone (9H-thioxanthen-9-one, TX) were determined in a few protic solvents (H2O, D2O, 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 S1-TX deactivation process in protic solvents is the formation of the S1-complex. The important modes of deactivation of the S1-complex are fluorescence (phiF approximately 0.4-0.5) and intersystem crossing to the T1 state. The S1-complex-->S0 internal conversion plays, at most, an insignificant role in S1-complex deactivation, which is evidenced by the absence of an isotope effect of protic solvents on the lifetime and quantum yield of fluorescence.
authors.affiliation: Photochemistry Laboratory, Faculty of Chemistry, Adam Mickiewicz University, Grunwaldzka 6, 60-780 Poznań, Poland. ewakryst@amu.edu.pl
authors.forename: Ewa
authors.initials: E
authors.lastname: Krystkowiak
authors.forename: Andrzej
authors.initials: A
authors.lastname: Maciejewski
authors.forename: Jacek
authors.initials: J
authors.lastname: Kubicki