Latest ArticlesNumerous researchers have paid attention to achieve metal-free phosphorescence by exploring new structures or new mechanisms. Herein, a facile way is introduced to endow a common fluorescence dye, tetrabromofluorescein (4Br-Flu), some fabulous optical characteristics such as dual emission including thermally activated delayed fluorescence, room-temperature phosphorescence (RTP), and the excellent pH-sensitivity. Shortly, 4Br-Flu with good light-emitting properties is composed into the polymer system. The multiple bromine atoms promote the spin-orbit coupling effect and facilitate triplet excitation. Especially, the hydrogen bonding network of the polymer restricts the molecular motion of 4Br-Flu so that the system can emit long-wavelength RTP when 4Br-Flu is doped into polyvinyl alcohol or co-polymerized with acrylamide. Due to the reversible transformation of protonation and deprotonation, the 4Br-Flu based polymer responded to acid and alkali like a phosphorescent switch which makes it an excellent hydrogen chloride/ammonia gas leak detector in dry environment.
Database-assisted global metabolomics has received growing attention due to its capability for unbiased identification of metabolites in various biological samples. Herein, we established a mass spectrometry (MS)-based database-assisted global metabolomics method and investigated metabolic distance between pleural effusion induced by tuberculosis and malignancy, which are difficult to be distinguished due to their similar clinical symptoms. The present method utilized a liquid chromatography (LC) system coupled with high resolution mass spectrometry (MS) working on full scan and data dependent mode for data acquisition. Unbiased identification of metabolites was performed through mass spectral searching and then confirmed by using authentic standards. As a result, a total of 194 endogenous metabolites were identified and 33 metabolites were found to be differentiated between tuberculous and malignant pleural effusions. These metabolites involved in tryptophan catabolism, bile acid biosynthesis, and β-oxidation of fatty acids, provided non-invasive biomarkers for differentiation of the pleural effusion samples with high sensitivity and specificity.
Water electrolysis is considered to be an effective and promising technology to make high-purity H2, however, the relationship between anion species and catalytic performance of electrocatalysts is still not completely clear. Herein, we report an anion engineering strategy to tune electrocatalytic water oxidation activity for Co-based materials. Novel hierarchical Co-based oxide/selenide/phosphide (Co-A, A = O, Se, P) hexagrams have been chosen as model materials. Electrochemical results and theoretical calculations reveal that the electron configuration, the electrical conductivity, and the oxidation potential of Co element in Co-A hexagrams could be moderated by the substitution of P atoms, which leads to the superior OER performance. Particularly, Co-P hexagram displays a low overpotential (η = 269 mV) at j = 10 mA/cm2 for the oxygen evolution reaction (OER) compared to Co-O hexagram (η = 399 mV) and Co-Se hexagram (η = 347 mV). This work is of great importance in understanding coordination atoms (O, Se and P) induced electrocatalytic properties of hierarchical Co-based materials.
Although magnetic stirring is frequently used to enhance the kinetics for adsorption, chemical and biochemical reactions, the introduction of stirrers inevitably leads to the adsorption of analytes and thus interferes with the efficiency of the chemical process or reaction. In this work, magnetic Fe3O4 nanorods with tunable length-to-diameter ratio were synthesized via a hydrothermal method and used as templates for the in-situ depositing of MIL-100(Fe) and gold nanoparticles. Such nanorod-based material can not only function as an adsorbent, nanozyme, and a heterogeneous catalyst for corresponding applications but also serve as a magnetic nanostirrer to enhance kinetics. As a proof-of-concept, the capture of bacteria pathogen, mimic-peroxidase-based colorimetric detection of hydrogen peroxide, and the catalytic reduction of selected organic pollutants were conducted using the as-synthesized Fe3O4@MIL-100(Fe)-Au nanostirrer with and without magnetic field. The results show that the rates of bacteria capture, mimetic enzyme reaction and catalysis were tremendously expedited. We believe this magnetic field-assisted approach holds great promise for future applications, because, not only does it eliminate the use of external magnetic stirrers and thereby decrease the risk of foreign pollution but also, is adaptable for nanoscale reaction systems where conventional stirring is not applicable due to size limitations.
A novel hydrogen-bonded organic frameworks (HOFs) FJU-200 has been constructed from N, N'-bis(5-isophthalic acid)naphthalimide (H4L). FJU-200 has a good dual-function of aniline and ultraviolet detection. FJU-200 is the first case of HOF with dual sensing of visual color changes and photoluminescence quenching for aniline detection, and the detection limit of aniline can reach 5.5 × 10−4 mol/L. Under ultraviolet FJU-200 will rapidly change from light yellow to rustic brown, which makes it possible to use FJU-200 to achieve minute-level ultraviolet detection. Moreover, for more convenient use, FJU-200 test papers are prepared. Using them, convenient and fast aniline or ultraviolet detection can be realized. The single-crystal X-ray structures show that compared with the original FJU-200, both and UV-FJU-200 have larger pore sizes, and the dihedral angles of the H2L2− in framework has been changed.
In order to reduce the greenhouse effect caused by the rapid increase of CO2 concentration in the atmosphere, it is necessary to develop more efficient, controllable, and highly sensitive adsorbing materials. In this study, the adsorption behavior of CO2 on BC3 nanosheets under an external electric field was explored based on density functional theory (DFT). It was found that CO2 experienced a transition from physisorption to chemisorption in the electric field range of 0.0060-0.0065 a.u.. In addition, the adsorption/desorption of CO2 is reversible and can be precisely controlled by switching on/off at the electric field of 0.0065 a.u.. The selective adsorption of CO2/H2/CH4 by BC3 can also be used to realize gas separation and purification under different electric fields. This study highlighted the potential application of BC3 nanosheets as a high-performance, controllable material for CO2 capture, regeneration, and separation in an electric field.
A novel flower-shaped zeolitic imidazolate framework (ZIF) doped organic-inorganic hybrid monolithic column (ZIF-HMC) was prepared by a simple sol-gel "one-step" method and utilized for efficient capillary microextraction (CME) of four brominated flame retardants. The prepared monolithic was characterized by Fourier transform infrared, scanning electron microscopy, X-ray photoelectron spectroscopy, energy disperse spectroscopy, and N2 adsorption-desorption. The parameters of CME were optimized by orthogonal array design. Under the optimal conditions, the ZIF-HMC showed excellent extraction efficiency, the limit of detection (LODs) and the limit of quantification (LOQs) were in the range of 0.52~3.1 μg/L and 1.7~10 μg/L, respectively, and the proposed method demonstrated good recovery (88.8%–116.6%) with the RSD less than 13.6% and a reusability of at least 30 times. The ZIF-HMC possessed great potential for separating organic pollutants and the strategy used here could be extended to prepare other derivatized HMC functionalized monoliths.
A convenient colorimetric approach for visual detection of melamine in raw milk was realized by using gold nanoparticles (AuNPs) stabilized by an unsymmetrical terpyridyl zinc complex with a thymine fragment at one terminal and a quaternary ammonium salt at the other. Even without pre-addition of melamine or relative additives, obvious color change from red to blue was observed by naked eye in the presence of trace amount of melamine, which was attributed to the alternation of aggregation state of AuNPs caused by the selective binding between the thymine fragment and melamine via triple hydrogen-bonding interactions. Remarkably, the detection limit for melamine was as low as 2.4 ppb, providing a highly sensitive and efficient approach for the visual detection of melamine.
Increasing the charge separation and the utilization efficiency of sunlight are essential factors in a photocatalytic process. In this study, we prepared crystalline N-CQDs@W18O49 heterostructures, through the in situ growth of W18O49 nanocrystals on nitrogen-doped carbon quantum dots (N-CQDs). N-CQDs@W18O49 nanocomposites showed high activity in the photodegradation of ciprofloxacin (CIP) and methyl orange (MO). The photodegradation activity of the optimized N-CQDs@W18O49-5 sample was four times higher than that of W18O49 under ultraviolet-visible (UV–vis) light irradiation. The photodegradation activity of N-CQDs@W18O49-5 sample was two times higher than that of W18O49 under near-infrared (NIR) light irradiation. The enhanced photosensitivity of the nanocomposites was attributed to the promotion of charge separation by N-CQDs and the local surface plasmon resonance (LSPR) effect of W18O49 under NIR light irradiation. This work provides a promising approach for designing and manufacturing photocatalysts with full-spectral responsiveness and improved charge separation.
Natural isoquinolinium alkaloids possess a wide range of biological activities. The design and synthesis of mesoionic isoquinoliniums is of great importance. This paper reports the synthesis of unique mesoionic thiazoloisoquinolinium thiolates stabilized by aromatization and 1, 3-dipolarization. Such compounds can be synthesized via the three component [2 + 2 + 1] cycloaddition reaction of isoquinolines with ethyl propionate and elemental sulfur in the absence of any metal catalyst and additives. Importantly, thiazoloisoquinolinium thiolates can be transformed to thioether-containing thiazoloisoquinolinium halides. A selective [4 + 2] cycloaddition can also be used to form S-bridged fused tetracyclic compounds with a thiothiamide ring unit and two quarternary carbon centres. Compound I-1 shows good bioactivity against the chlorophyll of duckweed (Lemna minor) with inhibition rate of 51.5 μg/mL.
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