Inorganics, Volume 12, Issue 5 (May 2024) – 9 articles

This study investigates the enhancement of surface properties in TiO₂-based coatings on the Ti-6Al-4V alloy through micro-arc oxidation (MAO), employing stevia sugar as a novel additive. By incorporating stevia sugar into acetate–glycerophosphate–tetraethoxysilane solutions used in MAO treatment, the porous morphology of TiO₂-based oxide layers is regulated. The incorporation of stevia moderates plasma discharge intensity, facilitating the formation of a uniform silicon-rich structure characterized by reduced porosity and pore size. This effect is attributed to the interaction between stevia and tetraethyl orthosilicate (TEOS), which modifies the TEOS hydrolysis process, thereby enhancing structural uniformity and stability while concurrently reducing plasma discharge intensity. Additionally, theoretical calculations offer a valuable understanding of the reactivity and interactions of stevia, TEOS, and their complex during the MAO process, laying the groundwork for further research and optimization in this promising field. Full article

In the search for a more effective chemotherapy for the treatment of Chagas’ disease, caused by Trypanosoma cruzi parasite, the use of gold compounds may be a promising approach. In this work, four gold(I) compounds [AuCl(HL)], (HL = bioactive 5-nitrofuryl containing thiosemicarbazones) were studied. The compounds were theoretically characterized, showing identical chemical structures with the metal ion located in a linear coordination environment and the thiosemicarbazones acting as monodentate ligands. Cyclic voltammetry and Electron Spin Resonance (ESR) studies demonstrated that the complexes could generate the nitro anion radical (NO₂⁻) by reduction of the nitro moiety. The compounds were evaluated in vitro on the trypomastigote form of T. cruzi and human cells of endothelial morphology. The gold compounds studied showed activity in the micromolar range against T. cruzi. The most active compounds (IC₅₀ of around 10 μM) showed an enhancement of the antiparasitic activity compared with their respective bioactive ligands and moderate selectivity. To get insight into the anti-chagasic mechanism of action, the intracellular free radical production capacity of the gold compounds was assessed by ESR and fluorescence measurements. DMPO (5,5-dimethyl-1-pirroline-N-oxide) spin adducts related to the bioreduction of the complexes and redox cycling processes were characterized. The potential oxidative stress mechanism against T. cruzi was confirmed. Full article

The stepwise synthesis and characterization of three new mixed-ligand organometallic tetranuclear platinum squares were achieved. All of the complexes were constituted by the conjunction of two (2,2′-bpy)Pt-terph-Pt(2,2′-bpy) (terph = p-terphenyl) fragments linked by a variety of N^N ligands (4,4′-bipyridine (4,4′-bpy), 1,4-di(pyridin-4-yl)benzene (dpbz), and 4,4′-di(pyridin-4-yl)-1,1′-biphenyl (dpbph)), which occupied the fourth coordination site of each metal center, giving rise to square-shaped molecules of the general formula [Pt₂(2,2′-bpy)₂(terph)(N^N)]₂. Consequently, the tetranuclear complexes, {[Pt(2,2′-bpy)]₄(μ-terph)₂(μ-4,4′-bpy)₂}{PF₆}₄ (7), {[Pt(2,2′-bpy)]₄(μ-terph)₂(μ-dpbz)₂}{PF₆}₄ (8), and {[Pt(2,2′-bpy)]₄(μ-terph)₂(μ-dpbph)₂}{PF₆}₄ (9) were constructed. The photophysical properties of these complexes were studied both in the solid state and in various solvents, revealing fluorosolvatochromism. Full article

Three new heteroleptic Ag(I) complexes, labeled as [AgL(POP)]BF₄ (1–3), were successfully synthesized and comprehensively characterized. Here, L represents 2,9-bis((E)-4-methoxystyryl)-1,10-phenanthroline (L1), 2,9-bis((E)-4-methylthiostyryl) -1,10-phenanthroline (L2), and 2,9-bis((E)-4-diethylaminostyryl)-1,10-phenanthroline (L3), while POP stands for Bis[(2-diphenylphosphino)phenyl] ether. The stability of these compounds in solution was confirmed through multinuclear 1D (¹H, ¹³C, ³¹P) and 2D NMR (COSY, NOESY, HMBC, HSQC) spectroscopies. Additionally, their molecular structure was elucidated via X-ray crystallography. The photophysical properties of the complexes were assessed both in the solid state and in solution (dichloromethane). Compounds 1–3 demonstrated moderate emissions in solution, with quantum yields ranging from 11–23%. Interestingly, their solid-state luminescent behavior differed. Large bathochromic shifts (42–75 nm) of the emission maxima and a decrease in quantum yields (2.5–9.5%) were evident, possibly due to the presence of excimers. Compound 3 stands out as a rare example of an Ag(I) red-color emitter. Full article

This study addresses the challenge of recycling adhesive bonds, as their disassembly is irreversible and damages the substrates. It explores the use of thermally expandable particles (TEPs), which, when heated, expand and weaken the bond. The magnetization of TEPs allows us to control their distribution using a magnetic field. The work aims to obtain magnetized TEPs, study their influence on resin curing, mechanical performance, and durability, test their mobility in graded bonds, and analyze the temperature-induced debonding process. TEPs are characterized using various techniques, including differential scanning calorimetry, nuclear magnetic resonance, and scanning electron microscopy. Additionally, the impact of 25 wt.% TEPs on epoxy resin curing is examined using the Kamal model. Adhesion and disassembly assessments were conducted through tensile shear tests using single-lap-joint specimens, while the bond durability was determined via wedge testing. It was found that magnetization reduces the debonding time, though it decreases shear strength while increasing bond durability. The crack formation energy is higher with magnetic TEPs, and total crack length is lower in long-term wedge tests. Once debonded, the substrates are sanded and reused as raw material. Full article

Pulsed laser deposition (PLD) is a simple and extremely versatile technique to grow thin films and nanomaterials from a wide variety of materials. Compared to traditional fabrication methods, PLD is a clean physical vapour deposition approach that avoids complicated chemical reactions and by-products, achieving a precise stochiometric transfer of the target material onto the substrate and providing control over the film thickness. Halide perovskite materials have attracted extensive attention due to their excellent photoelectric and photovoltaic properties. In this paper, we present an overview of the fundamental and practical aspects of PLD. The properties and preparation methods of the halide perovskite materials are briefly discussed. Finally, we will elaborate on recent research on the preparation of perovskite solar cells by PLD, summarize the advantages and disadvantages of the PLD preparation, and prospect the all-vacuum PLD-grown solar cells in a full solar cell structure. Full article

The development of efficient catalysts with visible light response for the removal of pollutants in an aqueous environment has been a hotspot in the field of photocatalysis research. A Zn_0.5Cd_0.5S (ZCS) nanoparticle/Bi₄O₅Br₂ ultra-thin nanosheet heterojunction was constructed by ultrasound-assisted solvothermal method. The morphology, structure, and optoelectronic properties of the composite were characterized by scanning electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, and UV–vis diffuse reflectance spectra. Under simulated visible light illumination, the photocatalytic performance was evaluated through degradation of tetracycline hydrochloride. Results show that the degradation effect by the optimum ZCS/Bi₄O₅Br₂ catalyst is superior to pure materials with the kinetic constant that is 1.7 and 9.6 times higher than those of Bi₄O₅Br₂ and ZCS, and also has better stability and reusability. Trapping experiments and electron paramagnetic resonance tests find that free radicals in the photocatalytic system are superoxide radicals and holes. This work provides a referable idea for the development of more efficient and recyclable photocatalysts. Full article

Thermal energy storage is at the leading edge of various applications, including waste heat recovery, solar storage and zero-energy buildings. Phase change materials (PCMs) can be utilized to store heat through reversible solid–liquid phase transitions. PCMs provide high energy storage capacity at a constant temperature. The volume change during the phase transition, on the other hand, causes inconsistency in crystallization and leakage, increasing the system’s complexity and shortening the lifetime of these materials. These shortcomings can be diminished by impregnation in a porous matrix or encapsulation with an inert shell, resulting in shape-stabilized PCMs that maintain their macroscopic shape during phase change. The synthesis and properties of Bi/ZnO nanocomposites were investigated in order to obtain shape-stabilized phase change materials. All samples consisted of metallic Bi and oxide, doped with 1–3% at. zinc. Heat storage capacities between 31 and 49 Jg⁻¹ were obtained, depending on the mass fraction of the metal. All samples had good thermal reliability, retaining their heat storage properties after 50 consecutive heating–cooling cycles. An average oxide layer thickness of 75–100 nm is sufficient to prevent the molten metal leakage at temperatures above its melting point, resulting in shape-stabilized PCMs. Full article