Two one-dimensional (1-D) cobalt(II) compounds, namely, {[Co(L1)(2,2′-bipy)]·0.5DMF}_n (1) and {[Co(bimb)(H₂O)₄]·(L2)·2DMF}_n (2) (H₂L1 = 2,2′-[benzene-1,4-diylbis(methanediylsulfanediyl)]dibenzoic acid, H₂L2 = 2,2′-(1,4-phenylenebis(methylene))bis(sulfanediyl)dinicotinic acid, 2,2′-bipy = 2,2′-bipyridine, bimb = 1,4-bis(benzoimidazo-1-ly)benzene), have been synthesized using cobalt(II) salts with long flexible carboxylic acids and N-containing ligands. Compounds 1 and 2 were systematically characterized by elemental analysis, infrared spectroscopy, and single crystal X-ray diffraction analysis. Both compounds display 1-D chain structures with two types of well-separated six-coordinated cobalt(II) ions possessing the same coordination sphere CoO₄N₂ but different coordination geometries: distorted trigonal prism and octahedron, respectively, which lead to different magnetic properties. Compound 1 exhibits more significant frequency-dependent signals and larger field-induced slow relaxation magnetization than compound 2. High frequency electron paramagnetic resonance (HF-EPR) studies further demonstrated the large anisotropy of both compounds with D values of −56.2 and +57.5 cm⁻¹, respectively.

This paper investigates the mechanism of nitrogen- and oxygen-containing functional groups in the collaborative adsorption of harmful gases by activated carbon through numerical simulation. The aim is to provide theoretical guidance for the industrial production of high-performance and universally applicable activated carbon. By employing density functional theory, we explore the impact of pyridine, pyrrole, carboxyl, and carbonyl groups on the co-adsorption of C₂H₆/SO₂/NO by activated carbon through analyzing surface electrostatic potential (ESP), physical adsorption energy, and non-covalent interaction. The findings demonstrate that the presence of nitrogen- and oxygen-containing functional groups within activated carbon surfaces enhances their polarity, while simultaneously forming strong non-covalent interactions with C₂H₆ and SO₂. The N-atom of NO can form a strong C-N ionic bond with the C-atom of the benzene ring. The adsorption site of NO is influenced by the nitrogen- and oxygen-containing functional groups. On an activated carbon model containing a pyrrole functional group, NO exhibits meta-adsorption behavior, while on activated carbon with pyridine, carboxyl, and carbonyl groups, it shows ortho-adsorption characteristics. The interaction between C₂H₆ and SO₂, as well as NO, primarily involves the H-bond, whereas the interaction between SO₂ and NO is predominantly driven by dipole–dipole interactions. These intermolecular forces significantly contribute to the mutual adsorption of these molecules.

A comprehensive analysis was conducted to examine the crystal phase composition, surface and cross-section morphology, elemental composition, thickness, and corrosion resistance of coatings. X-ray diffraction (XRD) was employed to investigate the texture and crystal phase of the materials while scanning electron microscopy (SEM) and energy-dispersive spectroscopy (EDS) were utilized to assess the surface and cross-section structure. Additionally, electrochemical techniques were employed to evaluate the corrosion performance. Compared to DC electroplating, the corrosion potential of pulsed galvanized ferroalloy alloy coating increased from −1031 mV to −1008 mV, and the corrosion current density decreased from 3.122 × 10⁻⁵ A∙cm⁻² to 0.321 × 10⁻⁵ A∙cm⁻². Moreover, the corrosion rate value of the coating obtained by the pulse rectifier (0.386 × 10⁻⁵ g m⁻² h⁻¹) was lower than that obtained by the DC power supply (3.75 × 10⁻⁵ g m⁻² h⁻¹). Additionally, pulsed electrodeposition reduced the iron content of the coating by 0.7%, thereby enhancing its corrosion resistance and flatness. The impedance parameters of the zinc–iron alloy coating acquired through the 30% duty cycle monopulser process exhibit superior performance compared to DC electroplating. Evidently, the monopulse coating’s structure enhances crystal packing density, augments coating thickness, improves adhesion to the substrate interface, and optimizes grain distribution uniformity. These factors are crucial determinants of the corrosion behavior exhibited by Ze–Fe coating.

In this study, pre-treated low-carbon steel substrates were electroplated with Zinc–Nickel (ZN) alloy composite coatings enhanced by the incorporation of nano-silicon dioxide (SiO₂) particles in an alkaline solution. ZN deposits with varying concentrations of nano-SiO₂—specifically, 1, 2, 3, 5, and 10 wt%—were achieved by adjusting the ratio between the nano-SiO₂ and ZN alloy electroplating solutions. The influence of the nano-SiO₂ content on both the quality of the coating and its corrosion behavior was investigated in detail. Scanning electron microscopy (SEM), energy-dispersive spectroscopy (EDS), and an atomic force microscope (AFM) were utilized to assess the surface, cross-section structure, elemental composition, and thickness of the coatings. Notably, the addition of nano-SiO₂ improved the microstructure of the coating, leading to a reduction in grain size as well as enhancements in uniformity and density while revealing that co-deposition reached an optimal concentration at 3 wt% nano-SiO₂. The corrosion behavior of coated specimens was evaluated through electrochemical impedance spectroscopy (EIS) and polarization techniques within a 3.5 wt% NaCl solution serving as a corrosive medium. Specifically, for typical prepared coatings, the corrosion current density decreased from 1.410 × 10⁻⁴ A·cm⁻² to 5.762 × 10⁻⁶ A·cm⁻², which is a remarkable reduction by one to two orders of magnitude relative to the SiO₂-free coatings mentioned previously. These findings provide a straightforward approach for selecting 3 wt% nano-SiO₂ as an effective additive in ZN composite coatings.

2,6-pyridine dicarboxylic acid (DPA) is an exceptional biomarker of notorious anthrax spores. Therefore, the rapid, sensitive, and selective quantitative detection of DPA is extremely significant and urgent. This paper reports a Zn(II) metal–organic framework with the formula of {[Zn₆(NDA)₆(DPBT)₃] 2H₂O·3DMF}_n (MOF-1), which consists of 2,6-naphthalenedicarboxylic acid (2,6-NDA), 4,7-di(4-pyridyl)-2,1,3-benzothiadiazole (DPBT), and Zn(II) ions. Structural analysis indicated that MOF-1 is a three-dimensional (3D) network which crystallized in the monoclinic system with the C2/c space group, revealing high pH, solvent, and thermal stability. Luminescence sensing studies demonstrated that MOF-1 had the potential to be a highly selective, sensitive, and recyclable fluorescence sensor for the identification of DPA. Furthermore, fluorescent test paper was made to detect DPA promptly with color changes. The enhancement mechanism was established by the hydrogen-bonding interaction and photoinduced electron transfer transition between MOF-1 and DPA molecules.

In this paper, the physical adsorption of volatile organic compounds (VOCs) such as methyl chloride (CH₃Cl), carbon disulfide (CS₂), dimethyl sulfide (C₂H₆S), and benzene (C₆H₆) by three models of activated carbon (without a functional group, with a pyridine-containing functional group, and with a pyrrole-containing functional group) was simulated. The surface electrostatic potential (ESP), physical adsorption energy, and non-covalent interaction between activated carbon and VOC molecules were analyzed based on the density functional theory (DFT). The effect mechanism of nitrogen-containing functional groups on VOC adsorption by activated carbon was determined. Our simulations showed that nitrogen-containing functional groups can change the surface ESP and polarity of activated carbon. The pyrrole functional group is conducive to CH₃Cl and CS₂ adsorption on the activated carbon plane, while the pyridine functional group is relatively small or even unfavorable for CH₃Cl and CS₂ adsorption on the activated carbon plane. The promotional effect of the pyrrole functional group on the adsorption of C₂H₆S is more significant than that of the pyridine functional group. The adsorption of C₆H₆ on activated carbon occurs through parallel-displaced π–π stacking interactions, in which functional groups have little influence on it. The adsorption energy of VOCs on the activated carbon plane is higher than that at the edge, so VOCs are more likely to be adsorbed on the activated carbon plane.