A Fresh Perspective on the Photophysics of Benzophenone

Abstract Aromatic ketones, such as benzophenone (BP), are widely used as photophores and triplet sensitizers in photochemical reactions. It is also employed in donor-acceptor delayed fluorescence systems. BP is the benchmark for studying the photophysics of aromatic ketones due to its efficient triplet generation. Despite its importance, many spectroscopic properties of BP have not been critically investigated in recent times. Here we report the characterization of BP using steady-state and time-resolved optical techniques in non-polar environments. The planar structural analogue, 10,10-dimethylanthrone (DMA), was also studied to assess the degree of importance that the BP molecular structure plays. Both BP and DMA exhibit direct triplet absorption and instantaneous phosphorescence, challenging current models of fast triplet formation in ketones. Surprisingly, high-energy excitation produces anti-Kasha S₂ emission alongside S₁. The intersystem crossing (ISC) mechanism was further clarified through transient absorption measurements. This work offers fresh insights into aromatic ketone photophysics.MAIN