Photophysics of 135-triaryl-2-pyrazolines

摘要

Abstract: The photophysics of 1,3,5-triphenyl-2-pyrazoline (I) and 1,3-diphenyl-5-(p-nitrophenyl)-2- pyrazoline (II) have been probed using steady-state and time-resolved fluorescence spectroscopy, laser flash transient absorption spectroscopy, and photochemical observations. II (and to a lesser extent, I) undergoes efficient H-D exchange at the 5-position on the pyrazoline ring when irradiated at 365 nm in CD$-3$/OD. These observations are interpreted in terms of initial photoexcitation to S$-2$/, which partitions between S$-1$/ and a non-emissive intramolecular charge-transfer state. This viewpoint helps rationalise some of the differences between solution and solid state photophysics of the pyrazolines. !