查看更多>>摘要：An organic ligand (3-[4-(diphenylamino)styryl] pyridine, L) was synthesized. By complexation of L with ZnBr2 and Zn(NCS)2 respectively in methanol and dichloromethane, two complexes ZnBr2L2 (dyel) and Zn(NCS)2L2 (dye2) were prepared. The two dyes exhibit good one-and two-photon fluorescence performance with high fluorescence quantum yields and large two-photon absorption cross section values. The mechanism of one-photon absorption and one-photon excited fluorescence based on computational results was obtained by TDDFT/CAM-B3LYP method. The results of living cell imaging experiments exhibit their compatibility in cytoplasm of HepG2 cells and show their potential in fluorescence microscopy bioimaging
查看更多>>摘要：Two new octa-coordinated ternary europium(IIl) complexes of the type [Eu(btfa)3(Br2-bpy)] (Eu-1) and [Eu (btfa)3(PhE2-bpy)] (Eu-2) (where btfa = 4,4,4-trifluoro-l-phenyl-l,3-butanedione, Br2-bpy = 5,5'-dibromo-2,2'-bipyridine, PhE2-bpy 5,5'-bis(phenylethynyl)-2,2'-bipyridine) together with a previously reported complex [Eu (btfa)30>py)] (Eu-3) have been synthesized. The complexes have been characterized by analytical and spectroscopic methods. The photophysical properties of the complexes have also been analyzed both experimentally and theoretically. The contribution of each ligand to the sensitized Eu(III) photoluminescence (PL) has been analyzed and is discussed. An energy transfer (ET) mechanism is proposed and discussed for the sensitized Eu(III) emission using experimental and theoretical data. The Eu(III) complex incorporating the parent bpy showed impressive performance as a double-emitting layer (EML) red organic light emitting diodes (R-OLEDs).
查看更多>>摘要：Schiff base generated by salicylaldehyde processes a hydroxyl group in the ortho position usually shows the properties of excited state intramolecular proton transfer (ESIPT). The six membered intramolecular hydrogen bonding network in the ground state of the proton transfer center accelerates the ESIPT process. In this work, a readily synthesized non-emissive probe (probe 1, "Off state") for the detection of cysteine (Cys) was designed based on the nucleophilic addition and departure reactions of cysteine and acrylate. The released chromophore (DEASH) emitted bright green fluorescence ("On state") with a quantum yield of 36.23% due to the process of ESIPT induced by the intramolecular hydrogen bonding. The specific sensing reaction was infeasible for the other thiols (even glutathione (GSH) and homocysteine (HCy)) and contributed to a supreme selectivity for Cys. Probe 1 also provides a sensitive detection process for Cys in aqueous buffer with a relatively low detection limit of 36.4 nM. In addition, the probe can be used for fluorescence imaging of exogenous and endogenous Cys in living cells as well as zebrafish with low cytotoxicity. These advantages indicate that the probe has important practical value for the monitoring of Cys in biological systems.
查看更多>>摘要：Three tetraphenylethylene-based fluorescent single crystals (TPE-AA-1, 2, 3) were formed from different solvents. Three different self-assembly modes were adopted due to the solvent effect. One HOFs (hydrogen-bonded organic frameworks) structure with characteristic porosity was obtained from acetonitrile/acetic acid as solvents. TPE-AA-3 show the best detection performance for nitro explosives.
查看更多>>摘要：Organic colourants have important applications in many fields. Their photostability is an important characteristic. Several methods to study photodegradation were compared in this work. Eosin Y (C.I. Generic name: Acid Red 87, EY) and crystal violet (C.I. Generic Name: Basic Violet 3, CV) were used as test compounds, both in solution and dyed on silk. Commonly applied methods were included, viz. Xenotest, Microfading-Tester, and light-box (Spectrolinker) experiments. A novel method was based on a liquid-core-waveguide (LCW) cell. After photodegradation on textile, extraction was performed using dimethyl sulfoxide (DMSO). The degraded solutions and extracts were analysed with liquid chromatography combined with diode-array detection and mass spectrometry. The degradation products were compared between techniques. Degradation in the LCW cell progressed much faster than in standard tests (Xenotest and Spectrolinker) and could be performed online, without a need for extraction or sample transfer. The degradation of CV in the LCW was comparable to its degradation in standard tests. For EY, there was a clear difference in degradation mechanisms between in-solution and on-textile samples. This could be due to the matrix or to incomplete extraction. Because the light sources used in the different experiments differed in energy and spectral emission, the results could not be quantitatively compared. However, the degradation products formed were shown to be independent of the light source. Therefore, the LCW is an attractive method for rapid and efficient studies into the chemistry of photodegradation.
查看更多>>摘要：We report a monochromatic dual-emission carbon nanodot (CD) as an unusual ratiometric fluorescence probe. The CD exhibits fluorescence spectral change from monochromatic blue to green emission, which is induced by Fe(III) ions as well as hydroxyl radicals. The monochromatic fluorescence spectral change of CD is utilized for a ratiometric fluorescence assay distinguishing Fe(III) and Fe(II) in aqueous media.
查看更多>>摘要：Optical and semiconducting properties of vacuum-deposited thin films of four hydrogen-bonded pigments were studied. Well-known l,4-diketo-3,6-diphenyl-pyrrolo-[3,4-c]-pyrrole (Ph-DPP) and l,4-diketo-3,6-(thiophen-2-yl)-pyrrolo-[3,4-c]-pyrrole (Th-DPP) were transformed to their 1,4-dithioketo heteroanalogues (Ph-DTPP and Th-DTPP) using Lawesson's reagent. X-ray single crystal structure determination confirmed the presence of CS-HN hydrogen bonds and a similar stack formation in both DTPPs, leading to relatively high decomposition temperatures, about 350 °C. According to density functional theory (DFT) calculations, thionation left HOMO (it-type) level almost unchanged, considerably destabilized non-bonding orbital (n-orbital) localized on thioketo group, and significantly decreased LUMO (it*-type) energy. Evolution of HOMO and LUMO energies was confirmed by cyclic voltammetry, establishing LUMO energy at-4.5 eV for both DTPPs, while a signature of high-lying n-orbital was detected through rut* transition in the far-red/near-infrared area of absorption spectra, interpreted with help of time dependent DFT calculations on monomer and stacked dimer geometry. The lowest optical band-gap among the pigments under study was found to be 1.4 eV for Ph-DTPP thin film. Field effect mobilities, determined on a bottom-gate top-contact transistor, show DPPs as p-type and DTPPs as n-type semiconductors. The highest electron mobility ue = 0.018 cm~2 V~(-1) s~(-1) was obtained for Ph-DTPP film in the device with aluminium source and drain electrodes.
查看更多>>摘要：The development of new strategies for the construction of highly selective and stable vapochromic system is still in great demand. Here, we present a highly selective and stable vapochromic system constructed by pillar[5] arene-based host-guest interactions between a pillar[5]arene (EtP5) and a phenazine derivative. The present material in this work showed specific selective responsiveness to chloroform vapor. The resultant dark orange solid sample was highly stable, which can maintain the color in air for at least two months at room temperature. Moreover, CHCI3 vapor responsive thin film and light-emitting diode (LED) was successfully prepared by coating the EtP5Dl complex on a glass sheet and a commercially available UV-LED. This work provided a new approach for the design and construction of selective and stable vapochromic systems with obvious color changes using pillar[5] arene-based host-guest interactions.
A. Prieto-CastanedaA. Lerida-VisoE. Avellanal-Zaballa
13页
查看更多>>摘要：We have designed and synthesized a family of Ir(III) metal complexes coordinated with two cyclometalated bis-fluorophenylpyridine ligands and an ancillary dipyrromethene which is functionalized with a mesityl group (Ir (dipy)-l), an a-chloroacetyl ester (Ir(dipy)-2) or a chain containing an ammonium cation (Ir(dipy)-3). The Ir (III) complexes feature a high triplet state population enabling red phosphorescence and efficient singlet oxygen generation. Ir(dipy)-2 and Ir(dipy)-3 are demonstrated to stain cells in both one-photon and two-photon confocal imaging. Moreover, Ir(dipy)-2 and Ir(dipy)-3 produce ROS in cells upon irradiation, inducing cell death by apoptosis. Colocalization studies in SK-Mel-103 cells show that Ir(dipy)-3 is partially accumulated in mitochondria and induces upon irradiation a disruption in their morphology. Overall our studies demonstrate that the prepared Ir(III) act as photosensitizers able to kill cells under irradiation, being suitable candidates for photodynamic therapy applications.
Christhian Irineu Dias PereiraCamila Fabiano de FreitasThais Lazzarotto Braga
10页
查看更多>>摘要：Curcumin (CUR) is a promising natural product in the field of biomedical applications, having a range of pharmacological effects. Despite this, clinical trials have reported poor absorption, low bioavailability, and rapid metabolism, which reduce its effectiveness. In general, these problems are related to the highly hydrophobicity of CUR, a limiting factor not only in its applications but also in its characterization. In fact, the spectroscopic description of CUR in homogeneous/microheterogenous media has a range of controversies, mainly about its self-aggregation process and its pKa determinations. To solve these drawbacks, die present work describes the concise spectroscopic analysis of CUR in different water-ethanol mixtures. The Critical Water Aggregation Percentage (CWAP), i.e., the limit percentage in which monomers are predominant is 50% of water. The Multivariate Analysis that employs the chemometric tools (MASDA) by Q-mode method was efficient in demonstrating that above 75% (water: ethanol v/v) CUR exists predominantly in self-aggregated form. In addition, the molecular modeling conducted in the ORCA 4.2 using the Hartree-Fock method associated with MASDA demonstrated that even at 30% (water: ethanol v/v) CUR dimers are present (—6%). From these conditions, the complex protolytic equilibria of CUR was evaluated in water-ethanol (30:70 v/v) with or without ionic strength. The pKa determination was also conducted by Multivariate Analysis. The obtained pKa values in the presence or absence of ionic strength control do not differ significantly. The protolytic equilibria can be represented in terms of the principal species: CUR0 * CUR~(-1) (enol/enolate), CUR~(-1) CUR~(-2) (phenol/phenolate) and CUR~(-2) CUR~(-3) phenol/phenolate). The chemometric also allows to obtain the spectra of the pure species and the molar absorptivity for each one. This set of results is especially important to complement the literature about the basic spectroscopy and physicochemical properties of CUR.
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