Latest ArticlesCarbon dots have unique advantages in biological applications owing to their excellent optical properties. However, the biosafety evaluation of carbon dots has limitations owing to cytotoxicity in vitro, and there is little pre-safety evaluation before in vivo and clinical applications. Whether the carbon dots are or not suitable for applications in vivo, evaluation analysis can be made based on hemolysis and changes in erythrocyte morphology. In this work, a green fluorescent N, S-doped carbon dots (N, S-CDs) were obtained by hydrothermal method, tobias acid, and m-phenylenediamine as precursors. N, S-CDs not only possessed excellent dispersibility, uniform particle size, high quantum yield (37.2%) and stable photoluminescence property but also retain their photostability and strong fluorescence intensity in the acid/alkaline solutions, different ionic strengths (NaCl) and under 365 nm UV illumination. Moreover, the N, S-CDs displayed low cytotoxicity and high cellular uptake efficiency in human umbilical vein endothelial cells (HUVEC) and excellent blood compatibility to the erythrocyte. It is foreseeable that N, S-CDs could be further studied as a promising biological imaging agent in vivo.
In this review, development of supported catalysts for the dehydrogenative synthesis of benzimidazoles from primary alcohols and 1, 2-phenylenediamine derivatives is briefly summarized. Among them, titania-supported iridium catalysts showed excellent activities under mild reaction conditions. Remarkably, the low-temperature activity of iridium catalyst was significantly affected by titania supports, and the reaction of 1, 2-phenylenediamine and benzyl alcohol in the presence of rutilesupported catalysts proceeded smoothly at 100 ℃ to give 2-phenylbenzimidazole in high yields of up to 88%. On the other hand, catalysts supported on anatase generally showed poor activity at 100 ℃. A significant relationship between CO uptake and the activity of titania-supported catalysts has been reported, indicating that well-reduced iridium species on rutile would be responsible for the predominant catalytic activity. The present results suggest the importance of the selection of suitable titania supports for the iridium catalysts.
Absolute one-handed chiral quinoline tetramers andoctamers containing different oxazolylanilines at the C-terminus have been synthesized. The absolute one-handed sense and diastereomeric excess values were valued by 1H NMR. X-ray crystal diffractionand CD studies reveal that the S-oxazolylaniline always induces a P-handed helicity and the absolute helicity is driven by the stable three-center hydrogen bonding between protons in the amide and N atoms in oxazolylaniline and adjacent quinoline ring. CPL investigations demonstrated that S-CQn-a~d are CPL active and its glum values are dependent on its length. Interestingly, the sizes of the substituents in the chiral centers are different, however, they exert no effect on the dissymmetric factors gabs and glum of quinoline oligoamide foldamers.
A metal-organic framework, Ce-FDM-50, was constructed by employing gallic acid featuring both carboxylate and pyrogallate as the coordinating sites and Ce(Ⅲ). The co-assembly of the carboxylates and pyrogallates with two metal ions have achieved a new type of paddle wheel secondary building unit. These building units were further joined by organic struts to obtain frameworks in sql topology. This synthetic approach could be expanded to five different lanthanide metals (Nd, Eu, Gd, Tb, Yb) for the construction of a series of isoreticular MOFs based on FDM-50, and even MTV-MOFs in which mixed lanthanide metals with specific ratios were distributed. In addition, featuring the lanthanide metals as the inorganic nodes in the network, Tb-FDM-50 showed distinct luminescence properties that could be furtherly tuned for variable applications.
Most of the current analytical methods depend largely on laboratory-based analytical techniques that require expensive and bulky equipment, potentially incur costly testing, and involve lengthy detection processes. With increasing requirements for point-of-care testing (POCT), more attention has been paid to miniaturized analytical devices. Miniaturized electrochemical (MEC) sensors, including different material-based MEC sensors (such as DNA-, paper-, and screen electrode-based), have been in strong demand in analytical science due to their easy operation, portability, high sensitivity, as well as their short analysis time. They have been applied for the detection of trace amounts of target through measuring changes in electrochemical signal, such as current, voltage, potential, or impedance, due to the oxidation/reduction of chemical/biological molecules with the help of electrodes and electrochemical units. MEC sensors present great potential for the detection of targets including small organic molecules, metal ions, and biomolecules. In recent years, MEC sensors have been broadly applied to POCT in various fields, including health care, food safety, and environmental monitoring, owing to the excellent advantages of electrochemical (EC) technologies. This review summarized the state-of-the-art advancements on various types of MEC sensors and their applications in POCT. Furthermore, the future perspectives, opportunities, and challenges in this field are also discussed.
In this work, the protic ionic liquid [DBUH] [Im] (1, 8-diazabicyclo[5.4.0]-7-undeceniumimidazolide) was developed as an efficient catalyst for the transesterification of ethylene carbonate with methanol to produce dimethyl carbonate. At 70 ℃, up to 97% conversion of ethylene carbonate and 91% yield of dimethyl carbonate were obtained with 1 mol% [DBUH] [Im] (relative to ethylene carbonate) as catalyst in 2 h. Even at room temperature, the conversion of ethylene carbonate can reach 94% and the yield of dimethyl carbonate can approach 81% for 6 h. Catalytic mechanism investigation showed the high catalytic efficiency of this ionic liquid results from the synergistic activation effect, wherein the cation can activate ethylene carbonate and the anion can activate methanol through hydrogen bond formation. Although the reusability of the ionic liquid need to be further improved, high efficiency and commercial availability of [DBUH] [Im] render it a promising catalyst for the preparation of dimethyl carbonate.
Botrytis cinerea is a necrotrophic fungus that affects various plant species. Chemical control is a necessity and as much as possible, eco-friendly conditions and bioresources to obtain these chemicals should be used. In this context, a series of products was obtained from salicylaldehyde using zinc as a powerful reagent and tested for antifungal activity against Botrytis cinerea.
Polymer electrolytes are essential for next-generation lithium batteries because of their excellent safety record. However, low ionic conductivity is the main obstacle restricting their commercial application. Composites with nanoparticles are a promising route to overcome this obstacle. In this work, lithium polystyrene sulfonate brushes (LiPSS) is anchored to silicon dioxide nanoparticles with chemical bonding using atom transfer radial polymerization (SI-ATRP). The composite polymer electrolytes are made by mixing vinylene carbonate and nanoparticles via a facile in situ polymerization process. The ionic conductivity of composite polymer electrolytes is improved to 7.2 ×10-4 S/cm at room temperature, which is attributed to the low degree of crystallinity of polymer electrolyte and the fast ion transport on the surfaces of polymer brush layers that act as a conductive network. The composite polymer electrolytes show a wide electrochemical window of approximately 4.5 V vs. Li+/Li and excellent cycling performance retention of approximately 95% after 100 cycles at ambient temperature. The results also prove that surface groups of ceramic nanoparticles are an important way to increase the electrochemical properties of composite polymer electrolytes.
Considering the importance and complexity of benzene oxidation on mineral oxide aerosol surfaces in the atmosphere, gas-phase 3d-transition metal oxide cations were used as models of active sites on mineral oxide aerosols to mimic the corresponding reactions. The various cations have been prepared by laser ablation and reacted with benzene in a linear ion trap reactor. Of the 103 systematically investigated cations, 39 clusters can oxidize benzene at room temperature. In addition to the adsorption channel, other five types of reaction channels were observed, including dehydrogenation of C6H6, charge exchange, hydrogen atom transfer, oxygen atom transfer, and the formation of C6H5O·radical, among which the first two pathways are prevalent and the formation of C6H6O+ cations has not been reported in literature. The insight into the benzene oxidation reactions derived from the gas-phase model systems is helpful to build a detailed picture of oxidative mechanisms of C6H6 and its derivatives over corresponding mineral oxide aerosols.
A versatile and efficient telescoped reaction sequence for the synthesis of tetrahydroisoquinolines (THIQs) is reported that uses TiCl4 to promote cyclization of a benzylaminoacetal derivative and Et3SiH for reduction of the intermediate 4-hydroxy-THIQ. This method is complimentary to the classical Pomeranz-Fritsch and related reactions since it tolerates electron-withdrawing substituents and allows access to 8-substituted THIQs.
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