Thermal expansion behaviors of Mn(Ⅱ)-pyridylbenzoate frameworks based on metal-carboxylate chains

Solvothermal reactions of MnCl₂ with pyridylbenzoic acids gave three-dimensional metal-carboxylate frameworks (MCFs), named MCF-34, MCF-43, and MCF-44, based on one-dimensional Mn-carboxylate chains. The crystal structure, stability, porosity, and framework flexibility of the new compound MCF-44 were studied in detail and compared with its analogs. Depending on their shapes and the bridging angles of the ligands, these compounds possess different network connectivities and porosities. Considering the pyridylbenzote ligands and Mn(II) ions as, respectively, 3- and 6-connected nodes, they resemble either the anatase (ant) or rutile (rtl) polymorph of TiO₂. Variable-temperature single-crystal X-ray diffraction studies revealed large thermal expansion coefficients for these compounds, which are probably related to the relatively flexible edge-sharing polyhedral structure of their Mn-carboxylate chains. Interestingly, the new compound MCF-44, with its highly porous rtl structure exhibits the largest thermal expansion coefficienct among the coordination polymers reported so far.     

Influence of relative phase on the nonsequential double ionization process of CO_2 molecules by counter-rotating two-color circularly polarized laser fields

We investigate the nonsequential double ionization(NSDI) of linear triatomic molecules by the counter-rotating two-color circularly polarized(CRTC) laser fields with a classical ensemble method. The results of the simulation reveal that NSDI yield strongly connected with the relative phase. The trajectory tracking method shows that the return time of the electron is controlled by the relative phase. In addition, when we change the CRTC laser wavelengths, the relative phase of the maximum and minimum yield of NSDI also changes. This shows that the influence of the Coulomb potential in the triatomic molecules on the electron return process cannot be ignored. This work will effectively promote the electronic dynamics study of NSDI for the triatomic molecule.     

Iron-mediated remote C–H bond benzylation of 8-aminoquinoline amides

An efficient and convenient method for C5-benzylation of quinoline frameworks is developed with the using of inexpensive FeCl₃ catalyst. A range of N-bisbenzylic and N-monobenzylic sulfonamides smoothly react with aliphatic amides and aromatic amides, giving the corresponding products in moderate to excellent yields.     

Synthesis and evaluation of two novel rhodamine-based fluorescence probes for specific recognition of Fec+ ion

Two low cytotoxic fluorescence probes Rb1 and Rb2 detecting Fe³⁺ were synthesized and evaluated. Rb1 and Rb2 exhibited an excellent selectivity to Fe³⁺, which was not disturbed by Ag⁺, Li⁺, K⁺, Na⁺, NH₄⁺, Fe²⁺, Pb²⁺, Ba²⁺, Cd²⁺, Ni²⁺, Co²⁺, Mn²⁺, Zn²⁺, Mg²⁺, Hg²⁺, Ca²⁺, Cu²⁺, Ce³⁺, AcO^?, Br^?, Cl^?, HPO₄^2?, HSO₃^?, I^?, NO₃^?, S₂O₃^2?, SO₃^2? and SO₄^2? ions. The detection limits were 1.87 × 10^?7 M for Rb1 and 5.60 × 10^?7 M for Rb2, respectively. 1:1 stoichiometry and 1:2 stoichiometry were the most likely recognition mode of Rb1 or Rb2 towards Fe³⁺, and the corresponding OFF–ON fluorescence mechanisms of Rb1 and Rb2 were proposed.     

A high-efficient amperometric hydrazine sensor based on novel electrospun CoFe2O4 spinel nanofibers

HeterojunctionFe_2O_3 nanoparticles(NPs), NiFe_2O_4 nanofibers(NFs), and CoFe_2O_4 NFs were synthesized by electrospinning and the subsequent thermal treatment processes. Characterization results indeed display the three-dimensional net-like textural structures of these as-electrospun spinel-type MFe_2O_4 NFs. The MFe_2O_4 NFs-based film configurations possess abundant micro/meso/macropores on their surface. These structures could afford more accessible transport channels for effective reduction of the mass transport resistance and improvement of the density of exposed catalytic active sites. All these advantages are responsible for the enhanced electro-catalytic performance of these MFe_2O_4 NFs in hydrazine oxidation. When used for hydrazine detection, CoFe_2O_4 NFs show the best catalytic efficiency.For example, the CoFe_2O_4 NFs possess a large sensitivity of 1327 mA cmà2(mmol Là1[à1in the linear range of 0.01 to 0.1 mmol Là1and 503 mA cmà2(mmol Là1)à1in the linear range of 0.1 to 11 mmol Là1, a response time of shorter than 3 s, good reproducibility and remarkable long-term stability. The superior catalytic efficiency, excellent stability, low cost, and ease of fabrication render CoFe_2O_4 NFs very promising materials in developing an electrochemical device that directly detects hydrazine.     

Palladium(0)‐Catalyzed Iminohalogenation of Alkenes: Synthesis of 2‐Halomethyl Dihydropyrroles and Mechanistic Insights into the Alkyl Halide Bond Formation

Although the advances on carbon halide reductive elimination have been made, the alkyl bromide and chloride analogues remain a challenge. Here, a palladium(0)‐catalyzed iminohalogenation of γ,δ‐unsaturated oxime esters is described, and the use of electron‐poor phosphine ligands proved to be crucial to promoting alkyl bromide and chloride reductive elimination. Furthermore, S_N2‐type alkyl bromide and chloride reductive elimination has also been established.     

N-Bridged Acyclic Trimeric Poly-Cyclodiphosphazanes: Highly Tuneable Cyclodiphosphazane Building Blocks

We have synthesized a completely new family of acyclic trimeric cyclodiphosphazane compounds comprising NH, NⁱPr, N^tBu and NPh bridging groups. In addition, the first NH-bridged acyclic dimeric cyclophosphazane has been produced. The trimeric species display highly tuneable characteristics so that the distance between the terminal N(H)R moieties can be readily modulated by the steric bulk present in the bridging groups (ranging from ≈6 to ≈10 Å). Moreover, these species exhibit pronounced topological changes when a weak non-bonding NH⋅⋅⋅π aryl interaction is introduced. Finally, the NH-bridged chloride binding affinities have been calculated and benchmarked along with the existing experimental data available for monomeric cyclodiphosphazanes. Our results underscore these species as promising hydrogen bond donors for supramolecular host–guest applications.     

Multivariate splines and hyperplane arrangements

In this paper, we use the so-called conformality method of smoothing cofactor (abbr. CSC) and hyperplane arrangements to study truncated powers and box splines in R². By the relation between hyperplane arrangements and truncated powers, we give the expressions of the truncated powers. Moreover, by means of the CSC method, the least smoothness degrees of the truncated powers and the box splines on each direction of partition edges are studied.     

Adsorption of catechol on a wet silica surface: density functional theory study

Marine mussel proteins adhere permanently to diverse wet surfaces via their catechol (1, 2-dihydroxybenzene) functionality. To elucidate the molecular mechanism underlying this water-resistant adhesion, we performed density functional theory calculations for the competitive adsorption of catechol and water on a wet silica surface. Results show the energetic spontaneity of the reaction; catechol displaces water molecules and adheres directly to the surface. This result was subsequently corroborated by our molecular dynamics simulation.