Divergent synthesis is a powerful and economical approach in synthetic chemistry and materials science. However, achieving precise control over divergent reactions using only reaction time as a variable is still rare. Herein, we show a time-dependent photochemical rearrangement driven by energy transfer catalysis under visible light. Remarkably, by simply adjusting the reaction time, we can selectively synthesize two distinct types of fluorinated strained rings using the same photocatalyst. Mechanistic experiments and computational studies reveal that this photochemical rearrangement follows a kinetically controlled pathway, involving a sequence of steps: diradical formation, 1,4-aryl migration, and 1,3-diradical formation. Interestingly, when the reaction time is extended, the newly formed difluoromethyl cyclopropanes can reversibly revert to the starting materials. This indicates that the final product is not simply kinetically or thermodynamically favored in the ground state potential energy surface. Instead, the excited state introduces additional complexity to the situation, as the starting materials are then fully converted into 1,1-difluorocyclopropanes through an excited-state thermodynamic control pathway-defined as the product distribution being governed by the relative thermodynamic stabilities of intermediates on the excited-state potential energy surface (PES), in contrast to conventional ground-state thermodynamic control, which relies on singlet ground-state PES stabilities under thermal conditions.

Organic long persistent luminescence (OLPL) materials are capable of exhibiting ultralong afterglow lasting for several hours. However, current design approaches for OLPL materials are still constrained, highlighting the need for further exploration. Here we propose a concept for building OLPL materials by thermally activated delayed fluorescence (TADF)-type organic afterglow emitters. The TADF afterglow emitter, which is a difluoroboron beta-diketonate luminescent molecule (SBF2) in this study, exhibit high molar absorptivity, multiple intersystem crossing and reverse intersystem crossing pathways, and high photoluminescence quantum yield. In addition, the TADF afterglow emitter of singlet excited state nature and millisecond lifetimes is conducive for efficient charge separation, which is the prerequisite for subsequent retard charge recombination and high-performance OLPL. Besides, the TADF emitter can simultaneously harvest singlet and triplet excitons upon retarded charge recombination to enhance OLPL. By employing a dopant-matrix strategy, SBF2 molecules and N,N,N ',N '-tetramethylbenzidine (TMB, an electron donor that promotes charge separation) were doped into optimal crystalline organic matrix, phenyl 4-methoxybenzoate (MeOPhB), which protects excited states and acts as an electron acceptor. The resultant SBF2-MeOPhB-TMB materials display bright OLPL with afterglow lasting up to 2 h. These materials hold significant potential for applications in anti-counterfeiting and data encryption.