查看更多>>摘要：Metal organic framework-based mixed matrix membranes and ratiometric fluorescent sensors have received significant attention in application of sensing. Herein, a two-dimensional europium-based metal organic frameworks, [Eu(L-N2)2-CL-C14)i.5-H2O] (CUST-506). (L-C14 = 2,3,5,6-tetrachloroterephthalic acid, L-N2 = 1,10-phenanthroline) has been synthesized and characterized. Then, by immobilizing water-stable CUST-506 into agarose hydrogels, the Eu-MOF-based mixed matrix membranes (CUST-506-based MMMs) were successfully prepared. The CUST-506-based MMMs exhibit not only the integrity and the metronidazole, picric acid (PA) sensing nature of Eu-MOF powder, but also excellent processability. Moreover, the Eu-MOF-based MMMs show distinguished water-stability. More interestingly, during the hydrothermal synthesis process, through anchoring the formic acid into the framworks to break the symmetrical coordination environment of the CUST-506, a one dimensional (ID) compound {[Eu(L-N2)-(L-C14)o.5(COOH)-2H2O]-(L-C14)0.s}(CUST-507) with two emission centers from Eu~(3+)-based centers and free L-C14 molecules is generated. CUST-507 displayes a unique ability of auto-calibration effect based on the dual emission mechanism and sensitive sensing of metronidazole and picric acid. This work highlights a simple fabrication strategy for MOF-based mixed matrix membranes and overcomes the environmental interference for ratiometric fluorescent sensor.
Tova N. WilliamsFrancine I. VacchiAmanda dos Santos
10页
查看更多>>摘要：As a new approach to permanent/oxidative hair dyes, we demonstrated that certain monoazo dyes containing substituents that enable diffusion into hair fibers and subsequent chelation/complexation using benign metal ions (Al~(3+) and Fe~(3+)), rather than a harsh oxidant and strong alkali, merit consideration in this application area. This is important, because billions of individuals worldwide color their hair using permanent hair dye products that can contain aromatic amines and phenols that display genotoxicity and/or skin sensitization (e.g., para-phenylenediamine, PPD). Herein, our work is extended to an examination of the toxicological properties and durability of metallizable monoazo dyes, in comparison to a commercially used permanent hair dye product. Results from the Safrnonella/microsome mutagenicity assay and from acute toxicity tests using aquatic test organisms (Daphnia similis, 48-h and Parhyale hawaiensis, 96-h) indicated that the proposed dyes were significantly less toxic than the top-eight permanent hair dye precursors utilized annually. Regarding durability, monoazo dye chelation in situ led to a higher degree of resistance to removal by washing than a commercial permanent hair dye. Taken together, these results further demonstrate die potential of the dyes as sustainable alternatives to conventional permanent hair dyes.
查看更多>>摘要：The striking similarities in chemical structures and properties between cysteine (Cys), homocysteine (Hcy) and glutathione (GSH) bring huge interferences to achieve specific detection of Cys, limiting the further physiological and pathological researches on Cys. Herein, a bis-reaction-triggered cascade-responsive highly specific Cys fluorescent probe CT-C was constructed, containing coumarin group as fluorophore, a,p-unsaturated ethanoyl as a Michael-addition site and 2-thiophenecarbonyl moiety as a nucleophilic substitution site, which overcame the interference of Hey and GSH by two successive reaction processes. CT-C presented a two-stage fluorescence response towards Cys, a fast and strong "turn-on" response in the first process and a lengthy "on-off' response in the subsequent second process, while CT-C only displayed a very slow and weak fluorescence enhancement towards Hey, and a slight fluorescence change towards GSH. To our knowledge, CT-C was the first reported probe utilizing two-stage cascade response for specific single detection of Cys. Furthermore, the novel two-stage response mode was also useful for the specific fluorescence visualization of exogenous Cys in BHK-21 cells.
查看更多>>摘要：Hydrogen sulfide is an essential gas signaling molecule in cells, internal conditions such as viscosity can affect the physiological and pathological functions of hydrogen sulfide. It has practical significance to detect the concentration of H2S under the condition of viscosity change. In our study, benzoindoles salt and N, N-dimethyl-4 (thiophen-2-yl)-aniline were conjugated, thus the probe had potential NIR emission capability. When viscosity increased, N-dimethyl-4(thiophen-2-yl)-anihne as a molecular rotor could response viscosity changes with 740 ran stronger fluorescent emission, C = C linker could sensitively response H2S with a turn on blue emission. Above process endowed the probe with the characteristic of dual response. The probe was used to study hydrogen sulfide concentration under viscosity change in the vivo by bioimaging. Most importantly, the probe was successfully used to detect changes in viscosity in a model of Parkinson's disease (PC-12 cells treated with glutamate), and the result indicated viscosity and H2S both increase under Parkinson's disease. The probe will have potential value in the further clarification of the pathogenesis of PD and provide a tool for further understanding the physiological and pathological significance of viscosity and H2S.
查看更多>>摘要：A new Intramolecular charge transfer (ICT) based fluorescent sensor for recognizing Th~(4+) ions has been successfully designed and developed. Sensor probe of 2-methyl-4-(4-(7,8,13,14-tetrahydrodibenzo[a,i]phenanthri-din-5-yl)phenyl)but-3-yn-2-ol (la) and 5-(4-ethynylphenyl)-7,8,13,14-tetrahydrodibenzo[a,i]phenanthridine (lb) selectively determined Th~(4+) ion with an instant color change from colorless to blue in CH3CN:H2O (9:1) solvent system. The detection limit (la: 3.4 x 10~(-8) M and lb: 1.4 x 10~(-8) M) for Th~(4+) ion was below the U.S Environmental Protection Agency's (EPA) permissible level in drinking water. In addition, la was applied to quantify thorium ions in natural water samples. The present sensor probe could detect thorium ions in biological cells using fluorescence bio-imaging with different emission channels. The detailed sensing mechanisms of la and lb for Th~(4+) ion have been investigated from NMR titrations, FTIR, Electrospray ionization (ESI)-Mass, and theoretical calculation techniques.
查看更多>>摘要：The analysis of nonlinear optical properties of thiazine dye molecules of Methylene Blue (MB+), located in the near-field zone of spherical gold nanoparticles, coated with a silicon dioxide shell (Au/SiO2 NPs. has been performed. The increase in the reverse saturated absorption, characteristic of MB~+ dye in the presence of gold nanoparticles under the 532 nm YAG:Nd~(3+) laser secpnd-harmonic pulses (10 ns) was found using Z-scan technique. The mechanisms of the plasmon nanoparticles effect on optical transitions, determining the reverse saturated absorption in methylene blue monomers are discussed. It is concluded that an increase in the effective cross section for triplet-triplet absorption of MB+ molecules in the presence of Au/SiO2 NPs makes the greatest contribution to the observed effect.
查看更多>>摘要：An easy and efficient approach for the synthesis of an important photoelectric intermediate 3-fluoro-2-iodithio-phene is developed. Therefrom, a polymer J52FF, featuring fluorination of the π-bridges on the backbone and side chains of the classical polymer, J52, is synthesized. J52FF displays a coplanar molecular configuration with the dihedral angles smaller than 2° in skeleton, a low-lying HOMO energy level of-5.62 eV, which is nearly aligned with the acceptor IT-4F, and a broad absorption range from 300 nm to 650 nm. The J52FF:IT-4F (1:0.8) blend shows a strong and complementary spectral absorption, a uniform fibrillar textured morphology and high and balanced charge mobilities. The inverted device based on J52FF:IT-4F blend obtained an encouraging power conversion efficiency (PCE) of 14.83% with the open-circuit voltage (Voc) of 0.90 V, the short circuit current (Jsc) of 23.21 mA cm~(-2), and the fill factor (FF) of 0.71 under the optimal conditions, which is one of the best PCE value among the ever reported BDT-alt-BTz derivatives or IT-4F based non-fullerene organic solar cells (NF-OSCs). It demonstrates that fluorination of polymer in skeleton is an efficient strategy for obtaining high performance.
查看更多>>摘要：A series of functionalized cotton fabrics (LG-ZnBDC-CCtn) were prepared by attachment of ZnBDC metal-organic framework with LbL deposition method on carboxylated cotton fabric (CCtn) and further encapsulation of ZnBDC with different luminescent guests (LG = Tb~(3+), La~(3+), Rhodanmine B or/and acridine orange). The characterization of LG-ZnBDC-CCtn by XRD, SEM and EDS showed that the structural integrity and morphology of ZnBDC on the CCtn surface were not destroyed after encapsulation. The photoluminescence behavior of sample LG-ZnBDC-CCtn was investigated by fluorescence excitation and emission spectra. After encapsulated with different luminescent guests, samples LG-ZnBDC-CCtn emitted different fluorescence. Although sample Tb/RhB-ZnBDC-CCtn with double LGs (Tb~(3+) and RhB) showed almost same visible color with RhB-ZnBDC-CCtn under sunlight, the orange yellow fluorescence of sample Tb/RhB-ZnBDC-CCtn was quite different with that of the single LG encapsulated sample Tb-ZnBDC-CCtn (green) or RhB-ZnBDC-CCtn (rose). A similar phenomenon was also observed in La/AO-ZnBDC-CCtn system. The fluorescence change of sample Tb/RhB-ZnBDC-CCtn could be due to a two-step fluorescence resonance energy transfer (FRET) among ZnBDC framework and luminescent guests. The visible color-change properties and technical performance of sample LG-ZnBDC-CCtn were evaluated with LAB color space and color strength.
查看更多>>摘要：The absorption and fluorescence properties of JV-alkylated 3,6-di (pyridin-4-yl)-2,5-dihydropyrrolo [3,4-c]pyr-role-l,4-dione (PyrDPP WH) derivatives in solution and the solid state are reported, along with the modulation of these properties under varying acidity or basicity. The compounds with hexyl (PyrDPP JV-Hex) and methoxy ethoxy ethyl (PyrDPP N-MEE) chains were synthesised from PyrDPP NH giving highly soluble dyes. In addition, the mono-substituted derivatives were also isolated. A range of solvents was explored to provide understanding regarding their potential use in applications ranging from organic electronics to sensors. Optically die dyes are highly fluorescent and, as a result of N-alkylation breaking the hydrogen bond network, emissive in the solid state with large Stokes shifts. The nature of the chain dictates the it interactions and packing of the materials, resulting in modulation of the solid-state absorption spectra and theoretical mobility predicted from die crystal structures. The methoxy edioxy ethyl chain twists out of the plane and bends to allow considerable molecular overlap and small interchromophore displacement with strikingly similar it interactions to die parent PyrDPP 1VH, resulting in a contribution of H-type aggregation to the absorption band and an order of magnitude improvement in theoretical mobility compared with die hexyl analogue. In contrast, PyrDPP lV-Hex possesses a distorted CH-it interaction between pyridyl and lactam units, with greater molecular displacement manifesting in dominant J-aggregation contribution to absorption band and moderate mobility. The results emphasise the potential for sidechain modification and show structural evidence for the potential benefits of the flexible polar chains. The nitrogen lone pair of the pyridyl ring can be protonated in acidic environment to produce a photometric response suggesting potential as a proton sensor. The mono-substituted compounds are responsive to both base and acid, making them interesting for molecular logic applications.
查看更多>>摘要：In solution-processed organic and inorganic halide perovskite solar cells (PSCs), managing the interfacial characteristics between multi-layers has been a crucial factor in determining their performance and stability. Here, we newly design an indolocarbazole-based organic molecule that can enhance the interfacial properties between a solution-processed NiOx hole transport layer and perovskite in p-i-n planar PSC. Especially, to be beneficial to this architecture, its visible transparency and energy level are optimized, and its chemical structure is crosslinked for better solution processability as a hole-selective interlayer. More importantly, it can passivate the defects in the perovskite film, consequently enhancing the quality of the film and suppressing non-radiative recombination in the devices. With this interface modification, we confirm that the performance and stability of PSC devices are largely enhanced.
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