A highly selective HBT-based “turn-on” fluorescent probe for hydrazine detection and its application

As one of the important industrial chemicals, hydrazine (N₂H₄) can be inhaled through the skin, leading to many serious health issues. In this paper, we constructed a novel turn-on fluorescent probe HBTM for N₂H₄ detection based on ESIPT and ICT mechanism by incorporating the methyl dicyanvinyl group to 2-(2′-hydroxylphenyl) benzothiazole (HBT) fluorophore. The probe showed the following advantages: high sensitivity with detection limit of 2.9 × 10^?7 M, high selectivity over other related interfering species, wide linear range of 0–140 μM and pH value adaptation. Moreover, the probe could detect N₂H₄ on paper strips and image N₂H₄ in living cells.     

Development of a light-up fluorescent probe for HRAS G-quadruplex DNA

The development of small-molecule G-quadruplex DNA probes has attracted significant attention in recent years. However, G-quadruplexes can display a wide variety of topologies, which process different structures and functions. Therefore, selective discrimination one G-quadruplex structure over another is promising. Herein, we reported the design, synthesis and biological evaluation of a long-chain fatty amine functionalized triphenylamine-quinolinium conjugate 1b. Significant enhancement of the fluorescence intensity (over 180 fold) was observed when 1b bound with HRAS G-quadruplex DNA, while much weaker enhancements were presented in the presence of other G-quadruplexes (45–90-fold) and single/double-stranded DNAs (less than 20-fold), indicating 1b had an excellent selectivity to HRAS. The details of the interactions were investigated by UV–Vis, FID and CD analysis. The results show 1b could interact and stabilize HRAS structure mainly by π-π stacking binding mode. The introduced amine chain of the structure core was found to be better in the terms of inducing selectivity toward G-quadruplex structure. In addition, the application of 1b as a fluorescent agent for living cell imaging was also demonstrated.     

Two copper(II)-bbtz modified Keggin and β-octamolybdate compounds captured in one-pot under hydrothermal conditions

Under hydrothermal conditions two compounds based on Keggin and β-octamolybdate, respectively, [Cu₂(bbtz)₄(SiMo₁₂O₄₀)] (1) and [Cu₂(bbtz)₄(Mo₈O₂₆)]_1/2·H₂O (2) (bbtz = 1,4-bis(1,2,4-triazol-1-ylmethyl)benzene), were synthesized in one-pot and characterized by single-crystal X-ray diffraction, elemental analyses, and IR spectroscopy. In compound 1, two adjacent wave-like Cu^II-bbtz lines are connected by SiMo₁₂ anions and bbtz to generate a ladder-like chain. Adjacent chains share the same Cu^II ions to build a three-dimensional (3-D) framework. In compound 2, the β-Mo₈ anions link Cu₃(bbtz)₂ subunits alternately to form a one-dimensional (1-D) chain. These chains connect each other through sharing Cu^II ions and a 3-D network is constructed. Moreover, we studied the electrocatalytic and photocatalytic activities of these two compounds. The results indicate that 1 and 2 show good electrocatalytic performance for the reduction of nitrite and bromate; they also exhibit photocatalytic properties for degradation of MB and RhB.     

Determination of Protonation Constants of O-Phospho-<Emphasis Type="SmallCaps">l</Emphasis>-serine in Aqueous Solution: Potentiometry,Microcalorimetry, NMR Spectroscopy and Quantum Chemical Calculations

O-Phospho-l-serine is one of the naturally occurring phosphorylated amino acids, having important pharmacological activity and bioactivity. The protonation constants of O-phospho-l-serine were determined by means of potentiometric titrations at 25 °C and ionic strength of 0.5 mol·L^?1 (NaCl). The heat effects of the protonation reaction of the O-phospho-l-serine were measured by direct calorimetry. NMR spectroscopy has demonstrated that the first protonation site occurs at the nitrogen atom in the amino group, followed by one of the oxygen atoms in the phosphono group, and finally the carboxyl oxygen atom. This trend is in good agreement with the enthalpy of protonation and quantum chemical calculations. These data will help to predict the speciation of O-phospho-l-serine in physiological systems.     

Corroborating study on the absolute configurations of trigochinins A–C

Trigochinins A–C (1–3) are three highly oxygenated daphnane-type diterpenes isolated from Trigonostemon chinensis. Their structures with the absolute configurations were initially assigned by a combination of spectroscopic data, X-ray crystallography (Mo Kα radiation) study and CD analysis. In the current study, the absolute configurations of trigochinins A–C were confirmed by single crystal X-ray diffraction (Cu Kα radiation) study, CD spectral analogy, and theoretical ECD study by using quantum chemical TDDFT calculations.     

Voltammetric Anion Sensors based on Redox‐active Ferrocene‐bearing Macrocyclic Amides

Reactions between 5‐ferrocenylisophthalic dichloride and 1,2‐bis(o‐aminophenoxy)ethane yield 1:1‐ and 2:2‐cyclization products with amide linkages, which are marked as L1 and L2 , respectively. The crystal structure of the 2:2‐macrocycle L2 is determined by X‐ray single crystal structure analysis. Interestingly, L2 affords a folded conformation due to the intermolecular π–π interaction between two isophthaloyl groups, so as to stabilize the marcocylic conformation. The electrochemical anion sensing studies of L1 and L2 show that they have a good ability to recognize H₂PO₄^–, and the 2:2‐cyclization products ( L2 ) with two ferrocene groups, more anion binding sites, and larger cavities, give better electrochemical anion recognition results than L1 .     

Double-Layered Plasmonic–Magnetic Vesicles by Self-Assembly of Janus Amphiphilic Gold–Iron(II,III) Oxide Nanoparticles

Janus nanoparticles (JNPs) offer unique features, including the precisely controlled distribution of compositions, surface charges, dipole moments, modular and combined functionalities, which enable excellent applications that are unavailable to their symmetrical counterparts. Assemblies of NPs exhibit coupled optical, electronic and magnetic properties that are different from single NPs. Herein, we report a new class of double-layered plasmonic–magnetic vesicle assembled from Janus amphiphilic Au-Fe₃O₄ NPs grafted with polymer brushes of different hydrophilicity on Au and Fe₃O₄ surfaces separately. Like liposomes, the vesicle shell is composed of two layers of Au-Fe₃O₄ NPs in opposite direction, and the orientation of Au or Fe₃O₄ in the shell can be well controlled by exploiting the amphiphilic property of the two types of polymers.     

Self-Optimization of the Active Site of Molybdenum Disulfide by an Irreversible Phase Transition during Photocatalytic Hydrogen Evolution

The metallic 1T-MoS₂ has attracted considerable attention as an effective catalyst for hydrogen evolution reactions (HERs). However, the fundamental mechanism about the catalytic activity of 1T-MoS₂ and the associated phase evolution remain elusive and controversial. Herein, we prepared the most stable 1T-MoS₂ by hydrothermal exfoliation of MoS₂ nanosheets vertically rooted into rigid one-dimensional TiO₂ nanofibers. The 1T-MoS₂ can keep highly stable over one year, presenting an ideal model system for investigating the HER catalytic activities as a function of the phase evolution. Both experimental studies and theoretical calculations suggest that 1T phase can be irreversibly transformed into a more active 1T′ phase as true active sites in photocatalytic HERs, resulting in a “catalytic site self-optimization”. Hydrogen atom adsorption is the major driving force for this phase transition.     

A Comparison of NO Reduction Over Mn–Cu/ZSM5 and Mn–Cu/MWCNTs Catalysts Assisted by Plasma at Ambient Temperature

Manganese–copper bimetal oxide catalysts supported on ZSM5 and acid-treated multi-walled carbon nanotubes (MWCNTs) were produced by incipient wetness impregnation for selective catalytic reduction of NO with dielectric barrier discharge plasma. Plasma can activate molecules even at ambient temperature, generating active oxygen species such as O, O₃, and HO₂ radicals, which can oxidize NO to NO₂ effectively. The SCR activity of Mn–Cu/MWCNTs was studied and compared to that of the Mn–Cu/ZSM5. The obtained samples were characterized by XRD, SEM, TEM, ICP, H₂-TPR, Raman spectroscopy, and XPS. The results show that Mn–Cu/MWCNTs catalyst possesses NO removal activity superior to that of the Mn–Cu/ZSM5 catalyst. MWCNTs-based catalyst attains NO removal efficiency of 88% at 480 J/L, while the ZSM5-supported catalyst achieves NO removal efficiency of 82% at the same energy density. The oxygen content increased from 3.33 to 19.07% on the nanotube surface after introducing Mn and Cu, which almost remained unchanged on ZSM5. The oxygen-containing functionalities are important for NO_x adsorption and removal. Moreover, the characterization revealed that CuO is the main phase of copper oxide, but copper dispersion decreases on Mn–Cu/ZSM5 surface because of the formation of copper dimer species. The manganese is well-dispersed on the catalysts, MnO₂ and Mn₂O₃ contents of Mn–Cu/MWCNTs are larger than that of Mn–Cu/ZSM5, MnO₂ is the predominant phase of manganese oxide.     

Recent Progress of Synthesis and Application in Au@MOFs Hybrid Materials

The combination of gold nanoparticles and metal–organic frameworks is one of the new directions of current research. It has applications in many aspects, especially as a catalyst for a variety of reactions. Therefore, this paper describes recent progress of synthesis and application in Au@MOFs hybrid materials.