Search Results (1,441)

Safranine T dye causes health problems such as skin and respiratory irritations. Hence, the safranine T dye was efficiently removed from aqueous media employing a simply synthesized manganese ferrite (MnFe₂O₄) nanoadsorbent. The synthesis of manganese ferrite nanoparticles was carried out by the pechini sol–gel approach using tartaric acid to serve as a chelating agent in addition to 1,2-propanediol to serve as a crosslinker. The TEM analysis showed that the shape of MnFe₂O₄ nanoparticles is semi-spherical, with an average particle size of 19.32 nm that coincides well with that measured from the XRD (18.89 nm). Further, the several factors that influenced the removal process of safranine T dye were examined, such as time, dye concentration, pH, and temperature. The ideal experimental conditions that achieved the highest safranine T dye removal percentage are pH 8, 80 min, and 298 K. The maximum adsorption capacity of MnFe₂O₄ nanoparticles towards safranine T dye equals 334.45 mg/g. The removal process of safranine T dye by manganese ferrite nanoparticles was chemical, exothermic, and well defined through the Langmuir equilibrium sorption isotherm in addition to the pseudo-second-order model. The synthesized manganese ferrite nanoparticles have the ability to be reused many times without losing their efficiency. Full article

Cancer is one of the leading causes of human death among all major diseases. Metal-based complexes are considered as the most promising vital part in the existing arsenal of cytotoxic candidates used in cancer therapy and diagnostics. The efforts of many scientific groups resulted in the development of numerous metal-based compounds featuring different biologically active organic ligands in order to modulate their bioactivity. Along with the main representatives as potential therapeutic agents, such as the complexes Pt(II)/Pt(IV), Pd(II), Ru(II)/Ru(III), Ag(I), Au(I)/Au(III), Ti(IV), V(IV) and Ga(III), many other transition metal and lanthanide complexes possessing antiproliferative activity are widely discussed in the literature. However, such drugs remain outside the scope of this review. The main purpose of the current study is to review the potential activity of main group metal- and metalloid-based complexes against the most common cancer cell types, such as carcinomas (lung, liver, breast, kidney, gastric, colorectal, bladder, ovarian, cervical, prostate, etc.); sarcomas; blastomas; lymphomas; multiple myeloma; and melanoma. Overcoming the long disregard of organometallic compounds of metals and metalloids from the main groups, a growing number of emerging anticancer agents remarkably prove this field offers an extensive variety of new options for the design of innovative unexplored chemopharmaceutics. Moreover, some of the metal complexes and organometallic compounds from these elements can exhibit entirely different, specific modes of action and biological targets. Obviously, exploitation of their distinct properties deserves more attention. Full article

Cobalt(II) thiocyanate-based tests are routinely used to screen cocaine products, with the formation of a blue species interpreted as a positive response. Two popular candidates for the origin of the blue color are an ionic coordination compound, frequently referred to as an ion pair, of the general form (HL)₂[Co(SCN)₄] or the coordination compound [CoL₂(SCN)₂], where L represents select nitrogenous bases. Given the high number of nitrogenous bases documented to yield false positives for cobalt(II) thiocyanate-based tests, a reasonable hypothesis is that both candidates are possible but their preferential formation depends on the specific nitrogenous bases screened. This hypothesis was tested through the crystallographic and spectroscopic analysis of reaction products of cocaine hydrochloride, lidocaine monohydrate hydrochloride, and benzimidazole exposed to a classic cobalt(II) thiocyanate reagent. Single-crystal X-ray diffraction revealed that the blue product isolated from benzimidazole test vessels is a coordination compound, with comparative ultraviolet–visible and Raman spectroscopy validating that blue precipitates collected from cocaine hydrochloride and lidocaine monohydrate hydrochloride reaction containers are ionic coordination compounds. Peaks corresponding to π-π* transitions in UV-vis at around 320 nm (cocaine hydrochloride: 320 nm, lidocaine hydrochloride: 323 nm) shift to a higher wavelength of 332 nm for the coordinated benzimidazole, and the broader d-d transitions at 550–630 nm show both a shift and change in envelope for benzimidazole coordinated with cobalt(II). The compound is a new polymorph of bis(benzimidazole)bis(thiocyanato-N)Cobalt(II), γ-[Co(Hbzim)₂(SCN)₂] (Hbzim = benzimidazole), and the differences in the intermolecular interactions to the two previous polymorphs were clarified by graph set analysis and Hirshfeld surface analysis. Furthermore, the coordination of aromatic nitrogen bases (such as benzimidazole) with Co(II) and aliphatic bases was compared by analyzing the Cambridge Structural Database, and the aromatic bases were found to have a shorter Co-N bond length compared to the aliphatic bases by around 0.02 Å. Full article

Herein, the synthesis and the structural as well as the photophysical characterization of five transition metal complexes bearing a neutral pyridine-pyrazole-based N^N*N^N ligand (L) acting as a tetradentate chelator are reported. The luminophore can be synthesized via two different pathways. An alkyl chain with a terminal tert-butyl moiety was inserted on the bridging nitrogen atom to enhance the solubility of the complexes in organic solvents. Due to the neutral character of L, metal ions with different charges and electronic configurations can be chelated. Thus, complexes with Pt(II) (C1), Ag(I) (C2), Zn(II) (C3), Co(II) (C4) and Fe(II) (C5) were synthesized. Single-crystal X-ray diffraction experiments showed that complex C2 exhibits a completely different structure in the crystalline state if compared with C3 and C5, i.e., depending on the chelated cation. The UV-vis absorption and the NMR spectra showed that the complexes dissociate in liquid solutions, except for the Pt(II)-based coordination compound. Therefore, the photophysical properties of the complexes and of the ligand were studied in the solid state. For the Pt(II)-based species, a characteristic metal-perturbed ligand-centered phosphorescence was traceable, both in dilute solutions as well as in the solid state. Full article

The discovery of regulated cell death (RCD) revolutionized chemotherapy. With caspase-dependent apoptosis initially being thought to be the only form of RCD, many drug development strategies aimed to synthesize compounds that turn on this kind of cell death. While yielding a variety of drugs, this approach is limited, given the acquired resistance of cancers to these drugs and the lack of specificity of the drugs for targeting cancer cells alone. The discovery of non-apoptotic forms of RCD is leading to new avenues for drug design. Evidence shows that ferroptosis, a relatively recently discovered iron-based cell death pathway, has therapeutic potential for anticancer application. Recent studies point to the interrelationship between iron and other essential metals, copper and zinc, and the disturbance of their respective homeostasis as critical to the onset of ferroptosis. Other studies reveal that several coordination complexes of non-iron metals have the capacity to induce ferroptosis. This collective knowledge will be assessed to determine how chelation approaches and coordination chemistry can be engineered to program ferroptosis in chemotherapy. Full article

Iron-sulfur [Fe-S] clusters, comprising coordinated iron and sulfur atoms arranged in diverse configurations, play a pivotal role in redox reactions and various biological processes. Diverse structural variants of [Fe-S] clusters exist, each possessing distinct attributes and functions. Recent discovery of [Fe-S] clusters in infectious pathogens, such as Mycobacterium tuberculosis, and in viruses, such as rotavirus, polyomavirus, hepatitis virus, mimivirus, and coronavirus, have sparked interest in them being a potential therapeutics target. Recent findings have associated these [Fe-S] cluster proteins playing a critical role in structural and host protein activity. However, for a very long time, metalloenzymes containing iron-sulfur clusters have been prone to destabilization in the presence of oxygen, which led to a delayed understanding of [Fe-S] proteins compared to other non-heme iron-containing proteins. Consequently, working with [Fe-S] proteins require specialized equipment, such as anaerobic chambers to maintain cofactor integrity, and tools like ultraviolet visible (UV-Vis) spectroscopy, mass spectrometry, X-ray crystallography, nuclear magnetic resonance (NMR), electron paramagnetic resonance (EPR), Mössbauer spectroscopy and electrochemical characterization. Many of these [Fe-S] cluster proteins have been misannotated as Zinc-binding proteins when purified aerobically. Moreover, the assembly of these iron-sulfur cluster cofactors have not been fully understood since it is a multi-step assembly process. Additionally, disruptions in this assembly process have been linked to human diseases. With rapid advancements in anaerobic gloveboxes and spectroscopic techniques, characterization of these [Fe-S] cluster-containing proteins that are essential for the pathogens can open up new avenues for diagnostics and therapeutics. Full article

A series of lead(II) complexes incorporating benzoate derivative ligands was prepared: [Pb(2MeOBz)₂]_n (1), [Pb(2MeOBz)₂(H₂O)]_n (2), [Pb₂(1,4Bzdiox)₄(DMSO)]_n (3), [Pb(1,4Bzdiox)₂(H₂O)]_n (4), [Pb(Pip)₂(H₂O)]_n (5), and [Pb(Ac)(Pip)₂(MeOH)]_n (6) (2MeOBz: 2-methoxybenzoate; 1,4Bzdiox: 1,4-benzodioxan-5-carboxylate; DMSO: dimethylsulfoxide; Ac: acetate; Pip: piperonylate; MeOH: methanol). All compounds were characterized via elemental analysis, ATR-FTIR spectroscopy, and powder XRD. In addition, the crystal structures of some compounds were elucidated. Compounds 1 and 2, involving 2-methoxybenzoate, were closely related, only differing in the presence of one extra aqua ligand found for the latter. However, this implies key changes in the studied properties, e.g., 2 shows solid-state luminescence that displays a different color as a function of the crystal orientation, while 1 does not. The crystal structure of 2 revealed a 1D coordination polymer. A similar relationship was found between compounds 3 and 4, incorporating 1,4-benzodioxan-5-carboxylate. In this pair, only 4, with aqua ligands, displayed a greenish-yellow-color solid-state luminescence. Furthermore, two new lead(II) piperonylate complexes, 5 and 6, were obtained from the reaction between lead(II) acetate and piperonylic acid. In water, all acetate ligands in the metal precursor were displaced and [Pb(Pip)₂(H₂O)]_n (5) was isolated, while in methanol, a mixed acetate–piperonylate complex, [Pb(Ac)(Pip)₂(MeOH)]_n (6), was precipitated. Considering only conventional Pb-O bonds, the crystal structure of 6 was described as a 1D coordination polymer, although, additionally, the chains were associated via tetrel bonds, defining an extended 2D architecture. Full article

Studying the ORR activity of platinum-based electrocatalysts is an urgent task in the development of materials for proton-exchange membrane fuel cells. The catalytic ink composition and the formation technique of a thin layer at the RDE play a significant role in studying ORR activity. The use of a polymer ionomer in the catalytic ink provides viscosity as well as proton conductivity. Nafion is widely used as an ionomer for research both at the RDE and in the MEA. The search for ionomers is a priority task in the development of the MEA components to replace Nafion. The study also considers the possibility of using the LF4-SK polymer as an alternative ionomer. The comparative results on the composition and techniques of applying the catalytic layer using LF4-SK and Nafion ionomers are presented, and the influence of the catalytic ink composition on the electrochemical characteristics of commercial platinum–carbon catalysts and a highly efficient platinum catalyst based on an N-doped carbon support is assessed. Full article

A series of ZnO-doped nitrogen-carbon materials (xZnO-N-C) with ZnO contents of 5–40% are prepared by a vacuum curing–carbonization strategy using polyamide-imide as the N-C source and zinc nitrate as the metal source for propane dehydrogenation (PDH). 20ZnO-N-C exhibits outstanding initial activity (propane conversion of 35.2% and propene yield of 24.6%) and a relatively low deactivation rate (0.071 h⁻¹) at 600 °C. The results of detailed characterization show that small ZnO nanoparticles (5.5 nm) with high dispersion on the catalyst can be obtained by adjusting the ZnO loading. Moreover, more nitrogen-based species, especially ZnN_x species, are formed on 20ZnO-N-C in comparison with 20ZnO-N-C-air prepared via curing carbonization without vacuum, which may contribute to the higher product selectivity and catalytic stability of 20ZnO-N-C. The active sites for the PDH reaction on the catalyst system are proposed to be C=O species and Zn²⁺ species. Moreover, the carbon deposition and the aggregation of ZnO nanoparticles are the causes of activity loss on this catalyst system. Full article

Thin films of metal–organic frameworks (MOFs) on polymer substrates and MOF/polymer mixed-matrix membranes play crucial roles in advancing the field of gas separation membranes. In this paper, we present a novel method for the direct formation of continuous ZIF-8 crystal films on a polymer substrate doped with Zn²⁺. Our approach involves ion exchange between the doped zinc ions within the substrate and sodium ions in the presence of a CH₃COONa additive, as well as interfacial complexation with eluted zinc ions and 2-methylimidazole (2-MeIM). The key factors affecting the formation of ZIF-8 crystals on the substrate were the concentrations of CH₃COONa and 2-MeIM. A time-course analysis revealed that the nucleation rate during the early stages of the reaction significantly affected the surface morphology of the resulting ZIF-8 crystal films. Specifically, a higher nucleation rate led to the formation of continuous small ZIF-8 crystal films. This innovative approach enables the fabrication of densely packed, uniform ZIF-8 crystal films. Full article

One electron oxidation of the monometallic alkenylacetylide complexes [Ru{C≡CC(R)=CH₂}(dppe)Cp*] (1) and [Ru{C≡CC(R)=CH₂}Cl(dppe)₂] (2) (R = Ph (a); R = 4-MeS-C₆H₄ (b)) generates in each case a dinuclear bis(allenylidene) complex [{Ru}₂{μ-C=C=C(R)–CH₂–H₂C–(R)C=C=C}][PF₆]₂ ({Ru} = Ru(dppe)Cp* ([3a,b][PF₆]₂); {Ru} = RuCl(dppe)₂ ([4a,b][PF₆]₂), containing an unsaturated ethane bridge between both allenylidene moieties. Deprotonation of this ethane bridge results in the formation of the previously reported octa-3,5-diene-1,7-diyndiyl-bridged bimetallic species [{Ru}₂{μ-C≡CC(R)=CH–HC=(R)CC≡C}] ({Ru} = Ru(dppe)Cp* (5a,b); {Ru} = RuCl(dppe)₂ (6a,b). The isolation of these complexes illustrates a general synthetic route to these conjugated bimetallic species from monomeric alkenylacetylide precursors. Electrochemical and spectroelectrochemical investigations evince the ready formation of the representative redox series [5a]ⁿ⁺, and TD-DFT calculations performed on optimised structures featuring the simplified {Ru(dmpe)Cp} coordination sphere [{Ru(dmpe)Cp}₂{μ-C≡CC(Ph)=HC–CH(Ph)CC≡C}]ⁿ⁺ ([5a^†]ⁿ⁺) (n = 0, 1, 2) reveal significant delocalisation of the unpaired charge in the formally mixed-valent species (n = 1), consistent with Class III assignment within the Robin–Day classification scheme. Full article

The current study provides an in-depth analysis of the biological properties of a Cu(II) complex (C₂₂H₂₄Cu₂N₆O₁₀) obtained from an aryl-semicarbazone ligand derived (L) from the condensation of 2,4-dihydroxy acetophenone and semicarbazide. The binding behavior of this complex with calf thymus DNA (CT-DNA) and bovine serum albumin (BSA) protein was explored using a combination of experimental and theoretical approaches. The results suggest that the complex binds with CT-DNA via a partial intercalation, and hydrophobic interaction. However, the complex binds to BSA protein predominantly through hydrogen bonding or van der Waals interactions rather than hydrophobic interactions. The molecular docking methodology was carried out to substantiate the experimental finding. Furthermore, the in vitro cytotoxicity study was conducted on human cervix uteri carcinoma (SiHa cancerous cell) lines upon exposure to the complex, and the findings reveal a considerable decrease in cell viability, when compared to the control. Overall, this study provides a comprehensive understanding of the biological potential of the Cu(II) complex and its potential as an anti-cancer agent. Full article

Linearity is an important factor that affects actuator accuracy. However, the high nonlinearity of KNN piezoelectric ceramics restricts their application in actuators. In this study, we used grinding stress to improve the linearity of ceramic chips, and used them to fabricate a laminated actuator. The ceramic sheets were ground to a thickness of 0.5 mm. During grinding, some areas of the ceramic changed from tetragonal to orthorhombic, owing to the grinding stress. The piezoelectric constant (d₃₃) increased from 198 to 268 pC/N. Notably, the linearity of the ceramics improved. Seven pieces of ground ceramics were bound, to fabricate a laminated multilayer actuator with a total thickness of 3.5 mm. A DC voltage was applied to the actuator, and the displacement was measured. The displacement reached 0.73 μm under a low driving voltage of 200 V. A linear regression analysis of the displacement–voltage relationship was performed, obtaining the regression equation of the actuator. The linearity correlation coefficient was approximately 0.9903, implying that the actuator exhibits a high accuracy. The grinding stress improved the linearity, together with the piezoelectric properties of the ceramic chips, thus improving the actuator accuracy. This research will promote the application of KNN piezoelectric ceramics in actuators. Full article

The preparation of environmentally friendly inorganic encapsulated pigments with a bright color and sufficient stability provides an effective strategy for expanding their applications in plastic, paint, glass, and ceramic decoration. The challenges facing the use of such pigments include the formation of a dense protective coating with the required endurance, the relatively weak color of the encapsulated pigments, and the preferable inclusion particle size. Environmentally friendly BiVO₄ is regarded as a very promising pigment for multiple coloring applications due to its brilliant yellow color with high saturation. However, its poor thermal and chemical stability greatly limit the application of BiVO₄. Herein, we report a sol–gel method to synthesize inorganic BiVO₄@SiO₂ yellow pigment with a core–shell structure. By controlling the synthesis conditions, including the particle size and dispersion of BiVO₄ and the calcination temperature, a BiVO₄@SiO₂ encapsulated pigment with excellent chromatic properties was achieved. The obtained environmentally friendly BiVO₄@SiO₂ pigment with encapsulation modification has a comparable color-rendering performance to BiVO₄, and it has a high thermal stability at 700 °C, excellent acid resistance, and good compatibility in plastics. The present research is expected to expand the application of yellow BiVO₄ pigment in harsh environments. Full article

The formation of a halogen-bonded network using four NHX-(CH₂)₃-NX-(CH₂)₃-NHX molecules (X = Cl, Br, or I) is investigated using DFT. The self-assembly of the four basic motifs results in a tube-like structure with C_4h symmetry, with one halogen-bonded network located at each end of the structure and one at its center. Each halogen-bonded network has four quasi-planar N-X···N interactions with binding energies that increase with the size of X. The structure is found to bind Li⁺ at each of the halogen-bonded networks, albeit more strongly at its center. The binding of Li⁺ is driven by halogen atom lone pairs that produce a rich electron density orthogonal to the halogen bond. The presence and strength of the interactions are further examined using AIM and NBO calculations. Lastly, IRC calculations are performed to examine the transitions between the Li⁺ complex minima and, thus, the potential for transporting the metal ion from one end of the tube to the other. Based on the tetrameric structure, a model intramolecular structure is built and considered as a potential host for Li⁺. In this case, the central intermolecular N-X···N network is replaced by an intramolecular Si-C≡C-Si network. Interestingly, both intermolecular and intramolecular structures exhibit similar Li⁺ binding abilities. Full article