Reversible Photoswitching between Fluorescence and Room Temperature Phosphorescence by Manipulating Excited State Dynamics in Molecular Aggregates

Abstract

Regulation of fluorescence–phosphorescence pathways in organic molecular aggregate remains a challenge due to the complicated singlet–triplet excited state dynamics process. Herein, we demonstrated a successful example (o‐BFT) to realize photoreversible fluorescence and room temperature phosphorescence (RTP) switching based on an effective strategy of integrating a phosphor (dibenzofuran) with a photoswitch (dithienylbenzothiophene). o‐BFT exhibited dual emission of fluorescence and RTP in both powder and doping polymer film. Notably, the long‐lived RTP of o‐BFT could be repeatedly erased and restored through reversible photocyclization and decyclization under alternate ultraviolet and visible photoirradiation. In‐depth theoretical and spectroscopic investigations revealed that the triplet inactivation was dominated by a photo‐controlled triplet‐to‐singlet Förster resonance energy transfer from light‐activated o‐BFT to photoisomer c‐BFT. Yet, the initial fluorescence could be preserved in this process to afford a photoreversible fluorescence‐RTP switching.

Base‐Tuning HOF‐Based Host–Guest Ultralong Organic Phosphorescence Systems with Phosphorescent Thermochromism Using for Information Security and Thermometer

“…Further on, TD-DFT calculations are also conducted to analyze ET progress. For Ma&Ct, several S n (4.472−4.602 eV) and T n (3.234−4.612 eV) states of Ct monomer and Ma/Ct dimer are all lower than T 1 (4.727 eV) state of Ma molecule (Table S8, Supporting Information), suggesting that the intermolecular tripletto-singlet FRET (FRET S-T ) can occur from T 1 state of Ma molecule to S n states of Ct monomer and Ma/Ct dimer, [15] and tripletto-triplet Dexter ET can conduct from T 1 states of Ma molecule to T n states of Ct monomer and Ma/Ct dimer (Figure 3e). [5,16] Because the singlet-triplet energy gap (∆E ST = 0.034 eV) of Ma/Ct dimer is smaller than that (0.046 eV) of Ct monomer, and SOC value [ξ(T 2 −S 1 ) = 6.748 cm -1 ] of Ma/Ct dimer is higher than that [ξ(T 2 -S 1 ) = 6.042 cm -1 ] of Ct monomer (Figure 3c,d; Table S9, Supporting Information), the high SOC value of RTP materials will result in the strong phosphorescence intensity, [4c,12b] thus the sky-blue phosphorescence of Ma/Ct dimer plays a major role in Ma&Ct system at room temperature.…”

A Highly Efficient Phosphorescence/Fluorescence Supramolecular Switch Based on a Bromoisoquinoline Cascaded Assembly in Aqueous Solution

“…[ 16 ] For example, Xu and coworkers constructed a fluorescence–RTP photoswitch that acted in both the powder form and in a doped polymer film, where the photoswitch was based on intramolecular light‐controllable photocyclization and decyclization processes. [ 17 ] In addition, Ma et al. reported a general approach to remotely regulate persistent luminescence in solids and DMF solutions by manipulating the isomerization of the energy acceptor.…”

“…[16] For example, Xu and coworkers constructed a fluorescence-RTP photoswitch that acted in both the powder form and in a doped polymer film, where the photoswitch was based on intramolecular lightcontrollable photocyclization and decyclization processes. [17] In addition, Ma et al reported a general approach to remotely regulate persistent luminescence in solids and DMF solutions by manipulating the isomerization of the energy acceptor. [18] Furthermore, Sessler and coworkers described a supramolecular network grafted with pillar[5]arene and spiropyran moieties to realize the time-dependent encryption of information based on the density of the host-guest crosslinks.…”

Photo-stimuli-responsive Organic Room-Temperature Phosphorescent Materials

“…In 2020, Xu et al synthesized a new photochromic emitter (46) by integrating dibenzofuran and a diarylethene group in one molecule (Figure 10A). 81 When compound 46 was doped in syndiotactic polystyrene (sPS), the obtained film exhibited bright recombination cyan luminescence due to the blue fluorescence at 437 nm and green phosphorescence at 530 nm. After stopping excitation, a green afterglow can be observed by the naked eye.…”

“…Photochromic molecules can undergo reversible photophysical property changes under photostimulus, which makes them good candidates for developing photo-stimuli-responsive materials. In 2020, Xu et al synthesized a new photochromic emitter ( 46 ) by integrating dibenzofuran and a diarylethene group in one molecule (Figure A) . When compound 46 was doped in syndiotactic polystyrene (sPS), the obtained film exhibited bright recombination cyan luminescence due to the blue fluorescence at 437 nm and green phosphorescence at 530 nm.…”