Two Thiourea-based Colorimetric Sensors for Anions: Structure and Binding Study

Two colorimetric thiourea-based chemsensors with two relatively rigid arms, 2A and 2B, were synthesized. Their binding abilities with halide anions, AcO^?, [Formula: See Text] were studied by UV-Vis spectroscopy in DMSO. The two sensors showed a notable selective color response to F^? anion from colorless to green-yellow in recognition. The structures of the two sensors and their binding behaviors are discussed. The association constants were calculated by nonlinear fittings of 1:1, 1:2 or 1:1 to 1:2.     

Photochemistry of iron(iii)-lactic acid complex in aqueous solutions

Photochemistry of a 1: 1 Fe^III-lactic acid complex, [Fe(Lact)]⁺, in aqueous solutions was studied by stationary photolysis, nanosecond laser flash photolysis (355 nm, 6 ns), and femtosecond pump-probe spectroscopy (400 nm, 200 fs). The quantum yield of photolysis of [Fe(Lact)]⁺ upon excitation at 355 nm is 0.4 and 0.22 in the deoxygenated and air-saturated solutions, respectively. Weak transient absorption in the range 500–750 nm was observed in the nanosecond experiments. It was assigned to a [Fe^II...-O-CH(Me)-COO^·]⁺ radical complex. The spectral properties of the ligand-to-metal charge transfer excited state and the characteristic time of formation of the radical complex (1.5 ps) were determined in the femtosecond spectroscopy experiments. A reaction mechanism was proposed, which involves inner-sphere electron transfer in the excited complex with the formation of a radical complex [Fe^II...-O-CH(Me)-COO^·]⁺ and its subsequent transformation to the end product of the photochemical reaction.     

Biochemical and Structural Studies of Conserved Maf Proteins Revealed Nucleotide Pyrophosphatases with a Preference for Modified Nucleotides

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Incompatible reaction evaluation and accident investigation of various acids in chemical industries

This article covers the incompatible properties of nitric acid (HNO₃) with formic acid (CH₂O₂), and more generally with various acids such as sulfuric acid (H₂SO₄), hydrochloric acid (HCl), and acetic acid (C₂H₄O₂). Differential scanning calorimetry (DSC) was employed to determine the thermal hazard such as heat of decomposition (ΔH _d), exothermic onset temperature (T ₀), etc., in various acids. T ₀ of HNO₃ and CH₂O₂ were determined as 50 °C using DSC. Thus it has been observed that HNO₃ mixed with CH₂O₂ should be prohibited during transportation, storage, and use. And more generally, process safety engineers and operator must take care to handle tanker and storage tank of typical acids in the transportation, storage, and manufacturing process. It is clear that there exists a need to follow and enforce in the chemical industries safety data sheets, globally harmonized system of classification and labeling of chemicals of United Nations (UN), education of safety and health, emergency response system, and process safety management. It is the aim of the present study concerning HNO₃ with various acids.     

Improved molten salt synthesis and structure evolution upon cycling of 0.5Li2MnO3·0.5LiCoO2 in lithium-ion batteries

The Li-rich cathode material Li_1.2Co_0.4Mn_0.4O₂(=0.5Li₂MnO₃·0.5LiCoO₂) was prepared by an improved molten salt method. The effects of sintering temperature and time on the physical and electrochemical properties of Li_1.2Co_0.4Mn_0.4O₂ were investigated. With increasing sintering temperature, excellent crystallinity and a stable structure are obtained, which lead to excellent electrochemical properties. However, the sample sintered at 900 °C has poor performance because its large powder diameter prolongs the transportation length of Li⁺ ions. Higher specific surface areas are obtained when samples are sintered at 850 °C for a shorter time, which leads to more activity and excellent charge/discharge capacity. The evolution of a derivative peak at about 3.0 V in the differential capacity (dQ/dV) curves is observed along with the formation of a spinel-like phase, which is verified by analysis using a high-resolution transmission electron microscope. Therefore, it is a simple and quick method to characterize the structure evolution upon cycling of Li-rich cathode materials by means of analysis of the derivative peak.     

Influence of the Li⋅⋅⋅π Interaction on the H/X⋅⋅⋅π Interactions in HOLi⋅⋅⋅C6H6⋅⋅⋅HOX/XOH (X=F,Cl, Br,I) Complexes

The influences of the Li???π interaction of C₆H₆???LiOH on the H???π interaction of C₆H₆???HOX (X=F, Cl, Br, I) and the X???π interaction of C₆H₆???XOH (X=Cl, Br, I) are investigated by means of full electronic second‐order Møller–Plesset perturbation theory calculations and “quantum theory of atoms in molecules” (QTAIM) studies. The binding energies, binding distances, infrared vibrational frequencies, and electron densities at the bond critical points (BCPs) of the hydrogen bonds and halogen bonds prove that the addition of the Li???π interaction to benzene weakens the H???π and X???π interactions. The influences of the Li???π interaction on H???π interactions are greater than those on X???π interactions; the influences of the H???π interactions on the Li???π interaction are greater than X???π interactions on Li???π interaction. The greater the influence of Li???π interaction on H/X???π interactions, the greater the influences of H/X???π interactions on Li???π interaction. QTAIM studies show that the intermolecular interactions of C₆H₆???HOX and C₆H₆???XOH are mainly of the π type. The electron densities at the BCPs of hydrogen bonds and halogen bonds decrease on going from bimolecular complexes to termolecular complexes, and the π‐electron densities at the BCPs show the same pattern. Natural bond orbital analyses show that the Li???π interaction reduces electron transfer from C₆H₆ to HOX and XOH.