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

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.

The research progress of rare earth agricultural light conversion film.

The light-converting agricultural film is a new high-end functional film that can convert ultraviolet light and yellow-green light, which is harmful or useless to plant photosynthesis, into red-orange light or blue-violet light required for photosynthesis. The potential advantages of light-converting agricultural film in efficiently utilizing solar energy and improving crop yield have attracted more and more attention from researchers and agricultural enterprises.The light-converting function is realized by adding a light-converting agent to the agricultural film. Therefore, the preparation of light-converting agents with excellent performance is the core of the development and utilization of light-converting agricultural films. The paper firstly summarizes the key research and development in the field of agricultural light-converting films in china. Then this paper summarizes the classification of light-converting agents, research progress, and preparation methods. Finally, this paper predicts the future development trend of light-converting agricultural films, in order to provide a reference for the research and development of stable and efficient light-converting agricultural films.

A new function of photochromic spiropyran: an efficient photoinitiator for two-photon polymerization.

Photochromic spiropyran molecule shows a brand new function for serving as an efficient photoinitiator to activate two-photon photopolymerization, thus paving the way for developing a fast 3D printing technology.

Exploiting radical-pair intersystem crossing for maximizing singlet oxygen quantum yields in pure organic fluorescent photosensitizers.

Fluorescent photosensitizers (PSs) often encounter low singlet oxygen (1O2) quantum yields and fluorescence quenching in the aggregated state, mainly involving the intersystem crossing process. Herein, we successfully realize maximizing 1O2 quantum yields of fluorescent PSs through promoting radical-pair intersystem crossing (RP-ISC), which serves as a molecular symmetry-controlling strategy of donor-acceptor (D-A) motifs. The symmetric quadrupolar A-D-A molecule PTP exhibits an excellent 1O2 quantum yield of 97.0% with bright near-infrared fluorescence in the aggregated state. Theoretical and ultrafast spectroscopic studies suggested that the RP-ISC mechanism dominated the formation of the triplet for PTP, where effective charge separation and an ultralow singlet-triplet energy gap (0.01 eV) enhanced the ISC process to maximize 1O2 generation. Furthermore, in vitro and in vivo experiments demonstrated the dual function of PTP as a fluorescent imaging agent and an anti-cancer therapeutic, with promising potential applications in both diagnosis and theranostics.

Redox-responsive Fluorescent Nanoparticles Based on Diselenide-containing AIEgens for Cell Imaging and Selective Cancer Therapy.

A fluorescent, diselenide-containing 9,10-distyrylanthracene (DSA) derivative (SeDSA) with aggregation-induced emission (AIE) characteristic was successfully synthesized and SeDSA nanoparticles (NPs) were prepared through a nanoprecipitation method. SeDSA could coassemble with an antitumor prodrug, diselenide-containing paclitaxel (SePTX), which could be obtained by precipitation, to form SeDSA-SePTX Co-NPs (Co-NPs). Molecular dynamics (MD) simulations reveal that the driving forces for the self-assembly behaviors of SeDSA NPs and SePTX NPs are π-π interactions and hydrophobic interactions, respectively, while the driving forces for Co-NPs include hydrophobic interactions between SeDSA and SePTX, π-π interactions between SeDSA molecules and hydrophobic interactions between SePTX molecules. Meanwhile, Se-Se bonds play a crucial role in balancing the intramolecular forces. These diselenide-containing nanoparticles (SeDSA NPs, SePTX NPs and Co-NPs) exhibit a high stability under physiological conditions and excellent reduction-sensitivity in the presence of the redox agent glutathione (GSH) because of the selenium-sulfur exchange reaction between diselenide and GSH. Both SeDSA NPs and Co-NPs show strong orange fluorescence emissions on the account of the AIE feature of SeDSA and they were easily internalized by HeLa and HepG2 cells. Distinctively, the Co-NPs combine the advantage of SeDSA and SePTX for cell imaging and antineoplastic activity, and exhibit selectivity of cytotoxicities between neoplasia cells and normal cells. This study highlights the development of diselenide-containing AIEgens as a unique approach to prepare uniform and stable fluorescent nanoparticles for the application in cell imaging and tumor treatment.