The emission spectra of styrene (ST)-triethylamine (TEA) systems were measured under steady-state illumination conditions in some tetrahydrofuran (THF)-protic solvent mixtures. The fluorescence spectrum of the ST-TEA system in THF consists of two bands (band A at 304 nm (fluorescence of ST) and band B at 460 nm (emission from an exciplex)). The intensity of band A increased and that of band B decreased with increasing amounts of protic solvents in THF-protic solvent mixtures. The increase in the intensity of band A was explained by the decrease in the concentration of free amine owing to the hydrogen-bonding interaction (or protonation) between TEA and protic solvents. The decrease in the intensity of band B was considered to be caused by the decrease in the concentration of free amine upon the addition of protic solvents and the enhanced conversion of the exciplex to an ion pair with increasing solvent polarity. The polar effect was expressed as a function of the relative permittivity of the solution.
- Polar effect
- Solvent effect
ASJC Scopus subject areas
- Molecular Biology
- Physical and Theoretical Chemistry