Pure organic room temperature phosphorescence (RTP) has unique advantages and various potential applications. However, it is challengeable to achieve organic RTP under visible and near-infrared (NIR)-light excitation, especially in aqueous solution. Herein we assemble difluoroboron β-diketonate compounds to form organic nanoparticles (NPs) in water. The resulting NPs are able to show efficient RTP, effective uptake, and bright imaging of HeLa cells under both visible-and NIR-light excitation. More strikingly, spectroscopic study, single-crystal Xray diffraction, and DFT calculation reveal that the efficient RTP in organic NPs is originated from dimers in their excited states. The multiple interactions and intermolecular charge transfer in the dimer structures are of significance in promoting the production of dimer triplet excited states and suppressing the nonradiative decays to boost the RTP under visible-and NIR-light irradiation in water.
We report the first highly efficient artificial light-harvesting systems based on nanocrystals of difluoroboron chromophores to mimic the chlorosomes, one of the most efficient light-harvesting systems found in green photosynthetic bacteria. Uniform nanocrystals with controlled donor/acceptor ratios were prepared by simple coassembly of the donors and acceptors in water. The light-harvesting system funneled the excitation energy collected by a thousand donor chromophores to a single acceptor. The well-defined spatial organization of individual chromophores in the nanocrystals enabled an energy transfer efficiency of 95 %, even at a donor/acceptor ratio as high as 1000:1, and a significant fluorescence of the acceptor was observed up to donor/acceptor ratios of 200 000:1.
A carbazole-containing difluoroboron β-diketonate complex (BCZ), which shows strong fluorescence in both the solid state and in organic solutions, is reported. The crystalline materials of BCZ obtained from different solvents display different emission colors. Single-crystal analysis reveals that the enhanced overlap between adjacent molecules induces increased excited-state delocalization and is responsible for the variation of the emission colors from yellow to red. The emission colors of the materials are effectively tuned by external stimuli such as grinding, heating, and solvent vapor. The powder X-ray diffraction, differential scanning calorimetry, thermogravimetric analysis, and 1 H NMR studies on materials of BCZ reveal that the thermochromic properties of BCZ are closely related to the removal of solvent molecules from the crystalline powders upon heating. Moreover, uniform 1D microstructures of BCZ obtained by solvent exchange in solution exhibit optical waveguide property with low optical loss.The ORCID identification number(s) for the author(s) of this article can be found under http://dx.
5419wileyonlinelibrary.com signifi cant efforts have been devoted toward developing optical sensors for oxygen. [6][7][8][9][10][11] Quenching of phosphorescence is a powerful tool for oxygen sensing due to its invasiveness, selectivity, and (when applied in specifi c systems) sensitivity to oxygen. In addition, it can measure and map oxygen with high-resolution and in real-time in cells and tissues. Ratiometric oxygen sensing at two wavelengths allows for better calibration of oxygen levels and is more desirable in the chemical and medical fi elds than simple phosphorescence quenching. In a ratiometric sensor, oxygen concentration is calculated from the phosphorescence of an indicator dye and the fl uorescence of a reference dye. In the literature, such ratiometric oxygen sensors have been constructed by incorporation of phosphorescent dyes such as Pd(II)/Pt(II) porphyrin complexes inside conjugated polymer nanoparticles, [ 8 ] quantum dots, [ 9 ] silica gels, [ 10 ] and metal-organic frameworks. [ 11 ] Supramolecular polymers (SP), which are prepared from low-molecular-weight monomeric units that are associated through reversible noncovalent interactions (and thus different compositional constituents) can be effi ciently incorporated by copolymerization and provide a promising scaffold to fabricate phosphorescent functional nanomaterial for oxygen sensing. [ 12,13 ] In contrast to the rapid development of conjugated polymer nanoparticles for biosensing and bioimaging applications, [ 8 ] nanomaterials constructed from supramolecular polymers for sensing are still rare. [ 14 ] This can be attributed to the small number of examples of supramolecular polymers that have been found to form uniform nanostructures in water and are compatible with biological systems. Recently, we reported the construction of water-dispersible nanoparticles based on ureidopyrimidinone (UPy) quadruple hydrogen-bonded supramolecular polymers by a mini-emulsion method. [ 15 ] These nanoparticles exhibit several characteristics that make them ideal candidate for biological and biomedical applications. First, they have good structural and functional tunability because they are constructed from low-molecular-weight molecules, allowing synthetic elaborations for specifi c applications. Second, the nanoparticles are dispersed uniformly in aqueous solutions and stable for reasonably long periods. Third, the sizes of the nanoparticles are controllable by the concentration and type of the skeleton units. The small sizes of the nanoparticles should produce minimal cell damage and allow better cellular uptakeThe fi rst example of a ratiometric optical oxygen nanoprobe based on a hydrogen-bonded supramolecular polymer has been reported. The supramolecular polymer based nanoprobe (SPNP) is prepared from the co-assembly of a bis-ureidopyrimidinone (bis-UPy)-containing phosphorescent indicator (Por(Pd)-bisUPy), fl uorescent reference dye (BF 2 -bisUPy), and skeleton unit (DPA-bisUPy) through quadruple hydrogen bonds by a mini-emulsion method. The water-...
We report a highly fluorescent difluoroboron β-diketonate derivative 1 which shows four emission colors (green, yellow, orange and red) with high quantum yields (41–74%) in four polymorphs and one amorphous state.
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