Latest ArticlesWe report on the synthesis of two acentric and one centrosymmetric Zn metal-organic complexes with 3-tetrazolemethyl pyridine spacers obtained in situ by hydrothermal routes. X-ray diffraction structural analysis reveals that they have the same equivalent nodes but with dissimilar topologies. The two acentric frameworks[Zn(Tzmp)Cl]n (1) and ([Zn(Tzmp)Br]n (2), HTzmp=3-tetrazolemethyl pyridine) are isomorphism which exhibit an acentric 3D framework with (10, 3)-b net called "ths", while the centrosymmetric complex ([Zn(Tzmp)N3]n (3)) features a distinctive 2D sheet with Shubnikov hexagonal plane net. Photo-luminescent studies suggest the ligand-field strength of coordinated negative ions (Cl- > Br- > N3-) has ordered adjusting effects on the emission redshift. The second harmonic generation (SHG) measurement shows that compounds 1 and 2 are nonlinear optically active, with SHG responses being 2/3 and half of the standard potassium dihydrogen phosphate (KDP), respectively.
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.
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.
The deletion of the C-terminal arginine of the anaphylatoxin protein C5a reduces it receptor binding affinity. Understanding how C-terminal arginine affects the structure and bioactivity of C5a is important for the development of C5a C-terminal mimics as drug candidates. Herein, we report the total chemical synthesis of rat C5a and its D-enantiomer with its C-terminal arginine deleted, namely L-rC5a-desArg and D-rC5a-desArg. The structure of rC5a-desArg was then determined by racemic crystallography for the first time. The C-terminal residues of rC5a-Arg were found to expand from the fourth helix in a continuous helical conformation. This C-terminal conformation is significantly different from that of the previously reported full-length of C5a, indicating that the deletion of C-terminal arginine residue could result in the destruction of a positively charged surface formed by two adjacent Arg residues in C5a.
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.
Direct, in situ selective detection of intracellular formaldehyde (FA) is of great significance for understanding its function in FA-related diseases. Herein, red carbon dots (RCD) are reported as label-free two-photon fluorescent nanoprobes for detecting and imaging of FA. Upon addition of FA, the -NH2 groups of RCD could quickly and specially react with aldehydes to form Schiff base and then the strong fluorescence of RCD with blue-shift emission is recovery due to the destruction of the hydrogen bond interaction between RCD and water. In addition, the nanoprobes exhibit outstanding photostability, rapid response (< 1 min), high sensitivity (~9.9 μmol/L) and excellent selectivity toward FA over other aldehyde group compounds. Notably, owing to the good cell-membrane permeability and biocompatibility, as well as the large two-photon absorption cross-section, the as-prepared RCD can be used as label-free nanoprobes for selectively detecting and imaging FA in living cells and zebrafishes through one-photon and two-photon excitation. Moreover, RCD could stain the tissue of zebrafishes at depths interval of up to 240 mm under two-photon excitation. This research implied that RCD are promising tools for directly and in situ imaging FA in vivo, thus providing critical insights into FA-related pathophysiological processes.
Developing large scale deposition techniques to fabricate thin porous films with suitable opto-electronic properties for water catalysis is a necessity to mitigate climate change and have a sustainable environment. In this review, flame spray pyrolysis (FSP) technique, a rapid and scalable methodology to synthesize nanostructured transitional metal oxide films with designed functionalities, is firstly introduced. Furthermore, applications in electrochemical (EC) and photoelectrochemical (PEC) water splitting for the production of hydrogen fuel is also presented. The high combustion temperature and the aggregation of flame aerosol ensure that the FSP-made films possess high crystallinity, tunable porosity and high surface areas, making this method suitable either as catalysts for EC water splitting or as efficient semiconductor materials for PEC water splitting. Finally, a perspective on the next generation FSP engineered films with potential applications in energy storage and conversion is described.
A novel near-infrared light photothemal-activated H2S-donating nanocomposite hydrogel was developed, through combination of a thermo-labile H2S donor and photothermal nanoparticles in agarose hydrogel. The polyethylenimine dithiocarbamate polymer, a thermo-labile compound, was synthesized as a novel H2S donor. The combination of a thermo-labile hydrogen sulfide donor and photothermal nanoparticles enabled the generation of H2S in agarose hydrogel upon irradiation with near-infrared light. The ability to modulate the photoirradiation for controlled generation and spatiotemporally release of H2S are its specific advantages. This photothermal spatiotemporally controlled H2S-releasing strategy was successfully applied to anti-inflammation treatment in a rat model, demonstrating its utility as a novel H2S-based therapeutic approach.
The temperature-dependent structural changes in 1-butyl-3-methylimidazolium tetrafluoride ([Bmim]FeCl4) magnetic ionic liquid (MIL) were investigated by using in-situ X-ray absorption fine structure (XAFS) combined with Raman spectroscopy and DFTcalculations. XAFS results revealed that the coordination number and bond length of Fe-Cl in the anion of[Bmim]FeCl4 MIL decreased with increments in temperature. These results directly reflected the dissociation of tetrahedral structure[FeCl4]-, and the formation of bridge-chain[Fe2Cl5]+, and[FeCl2]+ species in the anion of[Bmim]FeCl4 MIL. These behaviors indicated that[FeCl4]- dissociation was endothermic, and was promoted by increased temperature. The results obtained through XAFS were in agreement with those obtained through Raman spectroscopy and DFT calculations.
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