Inorganics

Open AccessArticle

New Insights into the Catalytic Activity of Second Generation Hoveyda–Grubbs Complexes Having Phenyl Substituents on the Backbone

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Assunta D’Amato

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Annaluisa Mariconda

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Pasquale Longo

Inorganics 2023, 11(6), 244; https://doi.org/10.3390/inorganics11060244 - 06 Jun 2023

Abstract

One of the most effective synthetic pathways to produce unsaturated compounds and polymers, meant for both industrial and pharmaceutical applications, is olefin metathesis. These useful reactions are commonly promoted by ruthenium-based precatalysts, namely the second-generation Grubbs’ catalyst (GII) and complexes bearing a styrenyl [...] Read more.

One of the most effective synthetic pathways to produce unsaturated compounds and polymers, meant for both industrial and pharmaceutical applications, is olefin metathesis. These useful reactions are commonly promoted by ruthenium-based precatalysts, namely the second-generation Grubbs’ catalyst (GII) and complexes bearing a styrenyl ether ligand, referred to as the second-generation Hoveyda–Grubbs’ catalyst (HGII). By altering the steric and electronic characteristics of substituents on the backbone and/or on the nitrogen atoms of the NHC ligand, it is possible to increase the reactivity and stability of second-generation ruthenium catalysts. The synthesis of an HG type II complex bearing two anti-phenyl backbone substituents (anti-HGII_Ph-Mes) with mesityl N-substituents is reported. The catalytic performances of the new complex were investigated in standard ring-closing metathesis (RCM) and ring-opening metathesis polymerization (ROMP) and compared to those of the analogue complex syn-HGII_Ph-Mes and to the classic HGII complex. A thorough analysis of the temperature dependence of the performances, along with a detailed comparison with the commercially available HGII, is conducted. The HGII_Ph-Mes complexes are more thermally stable than their parent HGII, as shown by the fact that their activity in the ROMP of 5-ethylidene-2-norbornene does not alter when the polymerization is carried out at room temperature after the complexes have been held at 180 °C for two hours, making them particularly interesting for materials applications. Full article

(This article belongs to the Special Issue N-Heterocyclic Carbene Metal Complexes: Synthesis, Properties and Applications)

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Open AccessArticle

Hydrogen Release and Uptake of MgH₂ Modified by Ti₃CN MXene

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Inorganics 2023, 11(6), 243; https://doi.org/10.3390/inorganics11060243 - 05 Jun 2023

Abstract

MgH₂ has a high hydrogen content of 7.6 wt% and possesses good reversibility under normal conditions. However, pristine MgH₂ requires a high temperature above 300 °C to release hydrogen, with very slow kinetics. In this work, we utilized Ti₃CN [...] Read more.

MgH₂ has a high hydrogen content of 7.6 wt% and possesses good reversibility under normal conditions. However, pristine MgH₂ requires a high temperature above 300 °C to release hydrogen, with very slow kinetics. In this work, we utilized Ti₃CN MXene to reduce the operating temperature and enhance the kinetics of MgH₂. The initial temperature of MgH₂ decomposition can be lowered from 322 °C for pristine MgH₂ to 214 °C through the employment of Ti₃CN. The desorbed MgH₂ + 7.5 wt% Ti₃CN can start absorption at room temperature, while the desorbed pristine MgH₂ can only start absorption at 120 °C. The employment of Ti₃CN can significantly improve the hydrogen release kinetics of MgH₂, with the desorption activation energy decreasing from 121 to 80 kJ mol⁻¹. Regarding thermodynamics, the desorption enthalpy changes of MgH₂ and MgH₂ + 7.5 wt% Ti₃CN were 79.3 and 78.8 kJ mol⁻¹, respectively. This indicates that the employment of Ti₃CN does not alter the thermal stability of MgH₂. Phase evolution studies through the use of X-ray diffraction and electron diffraction both confirm that Ti₃CN remains stable during the hydrogen release and uptake process of the composite. This work will help understand the impact of a transition metal carbonitride on the hydrogen storage of MgH₂. Full article

(This article belongs to the Special Issue State-of-the-Art and Progress in Metal-Hydrogen Systems)

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Open AccessCommunication

Organomonophosphines in Pt(η³-X¹X²X³)(PR₃), (X = N¹, N², N³; S¹, S², S³; or Te¹, Te², Te³) Derivatives: Structural Aspects

by

Milan Melník

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Veronika Mikušová

and

Peter Mikuš

Inorganics 2023, 11(6), 242; https://doi.org/10.3390/inorganics11060242 - 03 Jun 2023

Abstract

This paper covers nineteen Pt(II) complexes of the composition Pt(η³-X¹X²X³)(PR₃), (X = N¹, N², N³; S¹, S², S³; or Te¹ [...] Read more.

This paper covers nineteen Pt(II) complexes of the composition Pt(η³-X¹X²X³)(PR₃), (X = N¹, N², N³; S¹, S², S³; or Te¹, Te², Te³). These complexes crystallized in three crystal classes: triclinic (eleven examples), monoclinic (six examples), and orthorhombic (two examples). Each tridentate ligand creates two metallocyclic rings with common N², S², or Te² donor ligands of the types N¹C₂N²C₂N³, N¹C₂N²NC₂N³, S¹C₂S²C₂S³, S¹C₃S²C₃S³, and Te¹CNTe²NCTe³. The homotridentate ligand with monodentate PR₃ ligand builds up a distorted square planar geometry about Pt(II) atoms. The degree of distortion ranges from 0.029 to 0.092, and the reason for the distortion is discussed. There is an example that contains two crystallographically independent molecules within the same crystal. This is a classic example of distortion isomerism. Full article

(This article belongs to the Special Issue Advanced Inorganic Semiconductor Materials)

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Open AccessArticle

Novel BODIPY Conjugates with Myrtenol: Design, Spectral Characteristics, and Possibilities for Practical Application

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Svetlana A. Lisovskaya

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Larisa L. Frolova

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Olga V. Ostolopovskaya

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Ilfat Z. Rakhmatullin

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Vladimir V. Klochkov

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Elena Y. Trizna

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Airat R. Kayumov

Inorganics 2023, 11(6), 241; https://doi.org/10.3390/inorganics11060241 - 03 Jun 2023

Abstract

The synthesis of new fluorescent probes, based on biocompatible luminophors and exhibiting various specificities, is intensively developed worldwide. Many luminophors contain a hydrophobic group that limits their application for cell staining under vital conditions. Herein, we report the synthesis of two BODIPY molecules— [...] Read more.

The synthesis of new fluorescent probes, based on biocompatible luminophors and exhibiting various specificities, is intensively developed worldwide. Many luminophors contain a hydrophobic group that limits their application for cell staining under vital conditions. Herein, we report the synthesis of two BODIPY molecules—BF₂-meso-(4-butan/pentanamido-N-(((1S,5R)-6,6-dimethylbicyclo [3.1.1]hept-2-en-2-yl)methyl)-N,N-dimethylpropan-1-aminium)-3,3′,5,5′-tetramethyl-2,2′-dipyrromethene bromides—designed as 10, 11 with a spacer of either four or three CH₂ groups in length, respectively. These molecules present conjugates of BODIPY luminophors with (+)-myrtenol via a quaternary ammonium group. Both terpene-BODIPY conjugates demonstrated high fluorescence efficiency in various solvents such as OctOH, DMSO and water, and were characterized by their stability at pH 1.65–9.18. The fusion of the myrtenol, a monocyclic terpene, to the BODIPY fluorophore in the meso-substituent facilitated their penetration into the filamentous fungi Fusarium solani, while impairing the binding of the latter with S. aureus, K. pneumoniae and P. aeruginosa. The additional quaternary ammonium group between the myrtenol and fluorophore moieties restored the bacterial cell-staining while it did not affect the staining of fungi. Finally, the BODIPY conjugate 11 was able to stain both Gram-positive and Gram-negative bacteria by its interaction with their cell wall (or the membrane), as well as penetrating into filamentous fungi F. solani and staining their mitochondria. Full article

(This article belongs to the Special Issue Synthesis and Innovative Biological Activity of Boron-Containing Compounds)

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Open AccessArticle

Adsorption of Metal Atoms on SiC Monolayer

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Lei Jiang

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Yanbo Dong

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Zhen Cui

Inorganics 2023, 11(6), 240; https://doi.org/10.3390/inorganics11060240 - 30 May 2023

Abstract

The electronic, magnetic, and optical behaviors of metals (M = Ag, Al, Au, Bi, Ca, Co, Cr, Cu, Fe, Ga, K, Li, Mn, Na, Ni) adsorbed on the SiC monolayer have been calculated based on density functional theory (DFT). The binding energy results [...] Read more.

The electronic, magnetic, and optical behaviors of metals (M = Ag, Al, Au, Bi, Ca, Co, Cr, Cu, Fe, Ga, K, Li, Mn, Na, Ni) adsorbed on the SiC monolayer have been calculated based on density functional theory (DFT). The binding energy results show that all the M-adsorbed SiC systems are stable. All the M-adsorbed SiC systems are magnetic with magnetic moments of 1.00 μ_B (Ag), 1.00 μ_B (Al), 1.00 μ_B (Au), 1.01 μ_B (Bi), 1.95 μ_B (Ca), 1.00 μ_B (Co), 4.26 μ_B (Cr), 1.00 μ_B (Cu), 2.00 μ_B (Fe), 1.00 μ_B (Ga), 0.99 μ_B (K), 1.00 μ_B (Li), 3.00 μ_B (Mn), and 1.00 μ_B (Na), respectively, except for the Ni-adsorbed SiC system. The Ag, Al, Au, Cr, Cu, Fe, Ga, Mn, and Na-adsorbed SiC systems become magnetic semiconductors, while Bi, Ca, Co, K, and Li-adsorbed SiC systems become semimetals. The Bader charge results show that there is a charge transfer between the metal atom and the SiC monolayer. The work function of the K-adsorbed SiC system is 2.43 eV, which is 47.9% lower than that of pristine SiC and can be used in electron-emitter devices. The Bi, Ca, Ga, and Mn-adsorbed SiC systems show new absorption peaks in the visible light range. These results indicate that M-adsorbed SiC systems have potential applications in the field of spintronic devices and solar energy conversion photovoltaic devices. Full article

(This article belongs to the Special Issue Advanced Inorganic Semiconductor Materials)

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Open AccessArticle

Covalent Grafting of Eosin Y to the Giant Keplerate {Mo₁₃₂} through an Organosilicon Linker in Homogeneous Regime

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Kirill Grzhegorzhevskii

Inorganics 2023, 11(6), 239; https://doi.org/10.3390/inorganics11060239 - 30 May 2023

Abstract

The template effect of giant polyoxometalates (POM) shows promising results towards the supramolecular design of hybrid materials suitable for photocatalytic reactions. Here, we demonstrate a novel synthetic approach for covalently grafting the xanthene dye eosin Y (EY) to the nanoscale Keplerate POM {Mo [...] Read more.

The template effect of giant polyoxometalates (POM) shows promising results towards the supramolecular design of hybrid materials suitable for photocatalytic reactions. Here, we demonstrate a novel synthetic approach for covalently grafting the xanthene dye eosin Y (EY) to the nanoscale Keplerate POM {Mo₁₃₂} via an organosilicon linker (3-aminopropyltrimethoxysilane, APTMS) in a homogeneous regime. Using a phase transfer agent, tetrabutylammonium bromide, we solubilize the Keplerate POM modified with six {Si(CH₂)₃NH₂} groups, {Mo₁₃₂}@Si₆, in a series of organic solvents—acetonitrile, acetone, tetrahydrofuran, and dichloromethane—to perform post-functionalization by using an NHS-ester of EY. Both IR and Raman spectroscopy affirm the preservation of the POM’s structure and showcase an amide bond formation between POM and EY in the obtained conjugate {Mo₁₃₂}@Si₆@EY@TBA. Grafting’s success is observed through significant downfield shifting of EY’s aromatic protons’ signals on the ¹H NMR spectrum as compared to the spectra of EY and EY-NHS. The current synthetic approach enables us to exercise precise control of the stoichiometry in the POM-dye conjugates—1:1 for the POM-EY system—as confirmed by elemental analysis. Comprehensive photophysical analysis of {Mo₁₃₂}@Si₆@EY@TBA by means of UV-Vis and steady-state and time-resolved fluorescence measurements points to an existing strong interaction between molecular orbitals of EY and {Mo₁₃₂}, leading to a photoinduced electron transfer, partial fluorescence quenching, and elongation of the excited state’s lifetime. These findings demonstrate that using APTMS as an organosilicon linker in tandem with the Keplerate POM as a nanoscale template can be readily applied as a routine synthetic procedure for grafting various organic dyes or other organic molecules bearing a carboxylic group in their structure to the giant POM surface in a variety of aprotic organic solvents. Full article

(This article belongs to the Special Issue Advances in Polyoxometalates for Supramolecular Architecture, Biomimetics and Bioapplications)

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Open AccessArticle

Improved Oxide Ion Conductivity of Hexagonal Perovskite-Related Oxides Ba₃W_1+xV_1−xO_8.5+x/2

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Inorganics 2023, 11(6), 238; https://doi.org/10.3390/inorganics11060238 - 29 May 2023

Abstract

Hexagonal perovskite-related oxides such as Ba₃WVO_8.5 have attracted much attention due to their unique crystal structures and significant oxide ion conduction. However, the oxide ion conductivity of Ba₃WVO_8.5 is not very high. Herein, we report new hexagonal [...] Read more.

Hexagonal perovskite-related oxides such as Ba₃WVO_8.5 have attracted much attention due to their unique crystal structures and significant oxide ion conduction. However, the oxide ion conductivity of Ba₃WVO_8.5 is not very high. Herein, we report new hexagonal perovskite-related oxides Ba₃W_1+xV_1−xO_8.5+x/2 (x = −0.1, −0.05, 0.05, 0.1, 0.25, 0.4, 0.5, 0.6, and 0.75). The bulk conductivity of Ba₃W_1.6V_0.4O_8.8 was found to be 21 times higher than that of the mother material Ba₃WVO_8.5 at 500 °C. Maximum entropy method (MEM) neutron scattering length density (NSLD) analyses of neutron diffraction data at 800 °C experimentally visualized the oxide ion diffusion pathways through the octahedral O2 and tetrahedral O3 sites in intrinsically oxygen-deficient layers. By increasing the excess W content x in Ba₃W_1+xV_1−xO_8.5+x/2, the excess oxygen content x/2 increases, which leads to more oxygen atoms at the O2 and O3 oxygen sites, a higher minimum NSLD on the O2–O3 path, and a higher level of conductivity. Another reason for the increased conductivity of Ba₃W_1.6V_0.4O_8.8 is the lower activation energy for oxide ion conduction, which can be ascribed to the longer (W/V)–O2 and (W/V)–O3 distances due to the substitution of V atoms with large-sized W species. The present findings open new avenues in the science and technology of oxide ion conductors. Full article

(This article belongs to the Special Issue Layered Perovskites: Synthesis, Properties and Structures)

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Open AccessArticle

Effect of AST Atmosphere on Pt/C Electrocatalyst Degradation

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Inorganics 2023, 11(6), 237; https://doi.org/10.3390/inorganics11060237 - 28 May 2023

Abstract

The targeted development of novel stress testing protocols as well as the production of highly active and stable catalysts require abandoning a trial-and-error approach and transitioning to identifying the principal degradation mechanisms of electrocatalysts for PEMFCs under various conditions. Methodological aspects of research [...] Read more.

The targeted development of novel stress testing protocols as well as the production of highly active and stable catalysts require abandoning a trial-and-error approach and transitioning to identifying the principal degradation mechanisms of electrocatalysts for PEMFCs under various conditions. Methodological aspects of research related to both qualitative and quantitative assessment of the materials’ robustness against degradation and its mechanisms become the key issues. In this study, accelerated stress testing has been conducted in Ar and O₂ to identify the influence of the atmosphere on the degradation and durability mechanisms of the Pt/C catalysts. Initial and final parameters after the AST have been studied in detail by transmission electron microscopy and voltammetry using the rotating disk electrode technique. The Ostwald ripening (redeposition) of platinum particles has been established to be the predominant degradation mechanism during the testing in an O₂ atmosphere, this being the agglomeration of nanoparticles during the testing in Ar. An ultra-small size and a narrow size distribution of platinum nanoparticles, as well as their uniform spatial distribution over the surface of the carbon support, have been shown to allow both ORR activity to be increased and durability to be enhanced. Full article

(This article belongs to the Special Issue Nanostructured Platinum-Containing Electrocatalysts for Hydrogen Energy)

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Open AccessArticle

Pt Nanoparticles Supported on Ultrathin Ni(OH)₂ Nanosheets for Highly Efficient Reduction of 4-Nitrophenol

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Inorganics 2023, 11(6), 236; https://doi.org/10.3390/inorganics11060236 - 28 May 2023

Abstract

The synthesis of highly efficient heterogeneous catalysts with uniformly dispersed noble metal particles and a suitable size is crucial for various industrial applications. However, the high cost and rarity of noble metals limit their economic efficiency, making it essential to improve the catalytic [...] Read more.

The synthesis of highly efficient heterogeneous catalysts with uniformly dispersed noble metal particles and a suitable size is crucial for various industrial applications. However, the high cost and rarity of noble metals limit their economic efficiency, making it essential to improve the catalytic performance with lower noble metal loading. Herein, a two-step method was developed for the synthesis of uniformly dispersed ~3 nm Pt nanoparticles (NPs), strongly anchored on Ni(OH)₂ nanosheets (NSs), which was proven by adequate structural characterizations. XPS analysis demonstrated that Ni(OH)₂ NSs with abundant oxygen vacancies provided sufficient anchor sites for Pt NPs and prevented their agglomeration. The catalytic performance of Pt_n/Ni(OH)₂ (n (represents the addition amount of Pt precursors during the synthesis, μmol) = 5, 10, 15, and 20) NSs with controllable Pt loading were evaluated via the reduction of 4-nitrophenol to 4-aminophenol as a model reaction. The Pt₁₀/Ni(OH)₂ NSs exhibited the best activity and stability, with a reaction rate constant of 0.02358 s⁻¹ and negligible deterioration in ten reaction cycles. This novel synthetic method shows potentials for the synthesis of highly efficient noble-metal-supported catalysts for heterogeneous catalysis. Full article

(This article belongs to the Special Issue Metal Nanomaterials as Efficient Electrocatalysts)

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Open AccessArticle

Precipitative Coating of Calcium Phosphate on Microporous Silica–Titania Hybrid Particles in Simulated Body Fluid

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Inorganics 2023, 11(6), 235; https://doi.org/10.3390/inorganics11060235 - 28 May 2023

Abstract

Titania and silica have been recognized as potential drug delivery system (DDS) carriers. For this application, controllable biocompatibility and the suppression of the initial burst are required, which can be provided by a calcium phosphate (CP) coating. However, it is difficult to control [...] Read more.

Titania and silica have been recognized as potential drug delivery system (DDS) carriers. For this application, controllable biocompatibility and the suppression of the initial burst are required, which can be provided by a calcium phosphate (CP) coating. However, it is difficult to control the morphology of a CP coating on the surface of carrier particles owing to the homogeneous nucleation of CP. In this study, we report the development of a CP-coating method that homogeneously corresponds to the shapes of silica–titania (SiTi) porous nanoparticles. We also demonstrate that controlled surface roughness of CP coatings could be achieved in SBF using SiTi nanoparticles with a well-defined spherical shape, a uniform size, and a tunable nanoporous structure. The precipitation of CP was performed on mono-dispersed porous SiTi nanoparticles with different Si/Ti molar ratios and pore sizes. The pore size distribution was found to significantly affect the CP coating in SBF immersion; the surfaces of the nanoparticles with bimodal pore sizes of 0.7 and 1.1–1.2 nm became rough after CP precipitation, while those with a unimodal pore size of 0.7 nm remained smooth, indicating that these two pore sizes serve as different nucleation sites that lead to different surface morphologies. Full article

(This article belongs to the Special Issue New Advances into Nanostructured Oxides, 2nd Edition)

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Open AccessArticle

Synthesis, Structural Properties, and Resistance to High-Temperature Degradation of Perovskite Ceramics Based on Lanthanum–Strontium Ferrite

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Inorganics 2023, 11(6), 234; https://doi.org/10.3390/inorganics11060234 - 28 May 2023

Abstract

This work is dedicated to the study of the properties of perovskite ceramics based on lanthanum–strontium ferrite, and to the evaluation of their resistance to long-term thermal aging. As a method for obtaining perovskite ceramics, the method of solid-phase mechanochemical grinding and consequent [...] Read more.

This work is dedicated to the study of the properties of perovskite ceramics based on lanthanum–strontium ferrite, and to the evaluation of their resistance to long-term thermal aging. As a method for obtaining perovskite ceramics, the method of solid-phase mechanochemical grinding and consequent thermal annealing of the resulting mixtures was chosen. The novelty of the study consists in the assessment of the phase transformation dynamics in lanthanum–strontium ferrite-based ceramics in relation to the annealing temperature, alongside the study of the effect of the phase composition of ceramics on the resistance to high-temperature aging, which is characteristic of the operating modes of these ceramics as materials for solid oxide fuel cells. To study the properties, the methods of scanning electron microscopy, energy dispersive analysis, and scanning electron microscopy were applied. Pursuant to the outcome of elemental analysis, it was established that no impurity inclusions appear in the ceramic structure during the synthesis, and a growth in the annealing temperature results into a decline in the grain size and a growth in their density. During the analysis of the acquired X-ray diffraction patterns, it was found that a growth in the annealing temperature above 500 °C results in phase transformations of the LaFeO₃/SrFe₂O₄ → La_0.3Sr_0.7FeO₃/LaSr₂FeO₈/La₃FeO₆ type, followed by structural ordering and a decline in deformation distortions with a growth in the annealing temperature. An analysis of the conductive properties of ceramics has established that the dominance of the La_0.3Sr_0.7FeO₃ phase in the structure results in a growth in conductivity and a decline in resistance. Life tests for degradation resistance have shown that for three-phase ceramics, the rate of degradation and amorphization is significantly lower than for two-phase ceramics. Full article

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Open AccessArticle

A Molecular Understanding of the Flame Retardant Mechanism of Zinc Stannate/Polypropylene Composites via ReaxFF Simulations

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Inorganics 2023, 11(6), 233; https://doi.org/10.3390/inorganics11060233 - 27 May 2023

Abstract

As an important new flame retardant, zinc stannate (ZS) shows wide application prospects due to its many advantages. However, the flame retardant mechanism of composites made with polymer combined with ZS is still unclear. In particular, there is a lack of molecular level [...] Read more.

As an important new flame retardant, zinc stannate (ZS) shows wide application prospects due to its many advantages. However, the flame retardant mechanism of composites made with polymer combined with ZS is still unclear. In particular, there is a lack of molecular level description of the micro-scale flame retardant mechanism. The combustion mechanism through molecular simulation technology has become an important research paradigm in the field of fire, which can provide new insights for the development of new materials. This work studied the flame retardant mechanism of composites consistent with polypropylene (PP) and ZS using reactive force field molecular dynamics (ReaxFF MD) simulations. A new force field incorporating Sn/Zn/C/H/O components for ZS/PP composites combustion reactions was developed. Twenty different ZS/PP composites were analyzed for their combustion reactions at various temperatures. To investigate the flame retarding mechanism of ZS in composites, the evolutions of reactants, products, and reaction intermediates at the molecular scale were collected. It was revealed that the combustion temperature controlled the degree of oxidation by regulating the consumption of molecular oxygen during PP cracking. An increased combustion temperature reduced the oxygen consumption rate and overall oxygen consumption. As the PP component of composites exceeded 56%, oxygen consumption increased. Evolutions for carbon-containing intermediates and the products in combustions of PP/ZS composites were analyzed. The small carbon-based fragments were more likely to be produced for composites with low PP contents at high temperatures. These results are beneficial to design ZS/PP composites as flame retardant materials. Full article

(This article belongs to the Section Inorganic Materials)

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Open AccessArticle

Interaction of Copper(II) Ions with Certain Oxyacids and Azoles

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Nina Skorik

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Evgeniya Tomilova

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Ekaterina Pastushchak

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Irina Kurzina

Inorganics 2023, 11(6), 232; https://doi.org/10.3390/inorganics11060232 - 26 May 2023

Abstract

Compounds composed of [[Cu(HIm, metIm)_2–3L] ∙ nH₂O (n = 0, 2) were obtained during the interaction of slightly soluble tartrate and copper(II) salicylate composed of CuL ∙ nH₂O (n = 1–2, L²⁻ [...] Read more.

Compounds composed of [[Cu(HIm, metIm)_2–3L] ∙ nH₂O (n = 0, 2) were obtained during the interaction of slightly soluble tartrate and copper(II) salicylate composed of CuL ∙ nH₂O (n = 1–2, L²⁻—Tar²⁻, Sal²⁻) with imidazole (HIm) and 2-methylimidazole (metIm). Mono- and bi-ligand salts were analyzed; the process of their thermal decomposition was studied. The solubility constants K_S of the CuC₄H₄O₆ ∙ 2H₂O tartrate and CuC₇H₄O₃ ∙ H₂O salicylate of copper(II) with at ionic strength of 0.3 were determined. The IR spectroscopy method showed the participation in complexation of the nitrogen atom N(3) of imidazole and the oxygen atoms of the carboxyl groups of oxyacids, as well as the hydroxyl group of salicylic acid in the mixed-ligand salts of copper(II). The compositions and stability of the imidazole-tartrate(salicylate) copper(II) complexes in an aqueous solution were determined by performing photometry and spectrophotometry and of the monoligand complexes [CuTar] and [CuSal] were determined by solubility and isomolar series methods. Full article

(This article belongs to the Special Issue 10th Anniversary of Inorganics: Coordination Chemistry)

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Open AccessArticle

Novel Pyrimidinethione Hydrazide Divalent and Trivalent Metal Complexes for Improved High-Performance Antimicrobial and Durable UV Blocking Cellulosic Fabric

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Saeed El-Sayed Saeed

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Budoor A. Alomari

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Marwa. M. Abd El-Hady

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Ahmed N. Al-Hakimi

Inorganics 2023, 11(6), 231; https://doi.org/10.3390/inorganics11060231 - 26 May 2023

Abstract

Ultraviolet (UV)-protective and antimicrobial cotton fabrics are necessary for the protection of our skin. In this article, a pyrimidinethione hydrazide (PTH) derivative ligand was complexed with Mn, Co, Ni, Cu, Zn, and Cd as divalent metals and Fe and Cr as trivalent metals [...] Read more.

Ultraviolet (UV)-protective and antimicrobial cotton fabrics are necessary for the protection of our skin. In this article, a pyrimidinethione hydrazide (PTH) derivative ligand was complexed with Mn, Co, Ni, Cu, Zn, and Cd as divalent metals and Fe and Cr as trivalent metals to prepare highly antimicrobial and UV-blocking metal–pyrimidinethione hydrazide-modified cotton fabrics (M-PTH-C). The cotton sample treated (M-PTH) was found to show improved efficiency over pyrimidinethione hydrazide-modified cotton (PTH-C). Cadmium-PTH-C showed the highest performance of antimicrobial action against Staphylococcus aureus (Gram-positive bacteria), Escherichia Coli (Gram-negative bacteria), and Candida albicans (fungi) with zones of inhibition 31 mm, 18 mm, and 27 mm, respectively. Furthermore, all M-PTH-C samples showed no effect against Candida albicans, except Co, Ni, and Cd pyrimidinethione hydrazide-modified cotton with inhibition zones of 16 mm, 27 mm, and 22 mm. In addition, no compounds showed any activity against Aspergillus flavus except Cd-PTH-C, which gave an excellent performance, with a 33 mm inhibition zone. Furthermore, most modified cotton fabrics have excellent UV protection. Fe-PTH-C showed 113.3 as the highest Ultraviolet protection factor (UPF) compared to the other modified samples. The tensile strength test of all samples was also investigated. The values of tensile strength for the treated cotton samples are slightly affected compared to the untreated ones. Full article

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Open AccessPerspective

Toward High-Performances of Halide Light-Emitting Diodes: The Importance of Ligands Engineering

by

Le Ma

and

Feijiu Wang

Inorganics 2023, 11(6), 230; https://doi.org/10.3390/inorganics11060230 - 26 May 2023

Abstract

Halide perovskite light-emitting diodes (PeLEDs) have attracted great attention because of their superior optical properties, such as extremely high photoluminescence (quantum yield up to nearly 100%) of active layers with tunable wavelengths over the entire visible spectral range. With a suitable modification of [...] Read more.

Halide perovskite light-emitting diodes (PeLEDs) have attracted great attention because of their superior optical properties, such as extremely high photoluminescence (quantum yield up to nearly 100%) of active layers with tunable wavelengths over the entire visible spectral range. With a suitable modification of halide perovskites, carrier transport materials, and their interfaces, external quantum efficiencies exceeding 10%, 25%, and 20% have been achieved for blue-colored (465 nm), green-colored (512 nm), and red-colored (640 nm) LEDs, respectively. Many strategies for pursuing high performances of devices have been successfully demonstrated, among which ligand engineering has always played an important role in the active layer. Herein, we present a perspective to illustrate the effects and roles of the ligands in cesium lead bromide light-emitting diodes. This perspective is mainly classified into three parts: (1) ligands for CsPbBr₃ LEDs could improve radiative recombination of perovskites and contribute to better efficiency of LEDs; (2) ligands could confine CsPbBr₃ growth for blue emission of LEDs; (3) stabilities of materials and devices become better with ligand engineering. Finally, the summary and perspective on PeLEDs are highlighted and possible solutions are provided. Full article

(This article belongs to the Special Issue Recent Advances in Perovskite Optoelectronics: From Materials to Devices)

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Ligand Tuning in Cu(pyalk)₂ Water Oxidation Electrocatalysis

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Inorganics 2023, 11(6), 229; https://doi.org/10.3390/inorganics11060229 - 26 May 2023

Abstract

Molecular copper water oxidation electrocatalysts have been extensively studied in recent years for their potential use in artificial photosynthetic systems for solar energy conversion. Although ligand modification and its ability to influence catalytic properties is a key advantage of molecular systems, there are, [...] Read more.

Molecular copper water oxidation electrocatalysts have been extensively studied in recent years for their potential use in artificial photosynthetic systems for solar energy conversion. Although ligand modification and its ability to influence catalytic properties is a key advantage of molecular systems, there are, as yet, few examples of systematic studies of these effects. Our oxidatively resistant pyalk (2-pyridyl-2-propanoate) ligand forms a complex with copper(II) that catalyzes water oxidation and provides an attractive scaffold for systematic ligand tuning. Here, we report a series of analogous copper complexes with electron-donating (methoxy-) and -withdrawing (methoxycarbonyl-) groups at the para-position of the pyalk ligand. Trends in the pK_a and redox potential align with first-principles predictions for the electron-withdrawing and electron-donating groups. While the modified complexes show good activity for water oxidation, lowered faradaic efficiency in comparison to the parent complex highlights the importance of stability considerations for catalyst tuning. Full article

(This article belongs to the Special Issue Editorial Board Members’ Collection Series in “Water Oxidation Catalysts”)

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Open AccessArticle

The Role of Bulk Stiffening in Reducing the Critical Temperature of the Metal-to-Hydride Phase Transition and the Hydride Stability: The Case of Zr(Mo_xFe_1−x)₂-H₂

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Inorganics 2023, 11(6), 228; https://doi.org/10.3390/inorganics11060228 - 25 May 2023

Abstract

This study aims to shed light on the unusual trend in the stabilities of Zr(Mo_xFe_1−x)₂, 0 ≤ x ≤ 1, hydrides. Both the rule of reversed stability and the crystal volume criterion correlate with the increased hydride [...] Read more.

This study aims to shed light on the unusual trend in the stabilities of Zr(Mo_xFe_1−x)₂, 0 ≤ x ≤ 1, hydrides. Both the rule of reversed stability and the crystal volume criterion correlate with the increased hydride stabilities from x = 0 to x = 0.5, but are in contrast with the destabilization of the end member ZrMo₂ hydride. The pressure-composition isotherms of ZrMo₂-H₂ exhibit very wide solid solubility regions, which may be associated with diminished H–H elastic interaction, u_elas. In order to discern this possibility, we measured the elastic moduli of Zr(Mo_xFe_1−x)₂, x = 0, 0.5, 1. The shear modulus, G, shows a moderate variation in this composition range, while the bulk modulus, B, increases significantly and monotonically from 148.2 GPa in ZrFe₂ to 200.4 GPa in ZrMo₂. The H–H elastic interaction is proportional to B and therefore its increase cannot directly account for a decrease in u_elas. Therefore, we turn our attention to the volume of the hydrogen atom,

v_{H}

, which usually varies in a limited range. Two coexisting phases, a Laves cubic (a = 7.826 Å) and a tetragonal (a = 5.603 Å, c = 8.081 Å) hydride phase are identified in ZrMo₂H_3.5, obtained by cooling to liquid nitrogen temperature at about 50 atm. The volume of the hydrogen atom in these two hydrides is estimated to be 2.2 Å³/(H atom). Some very low

v_{H}

values, have been reported by other investigators. The low

v_{H}

values, as well as the one derived in this work, significantly reduce u_elas for ZrMo₂-H₂, and thus reduce the corresponding critical temperature for the metal-to-hydride phase transition, and the heat of hydride formation. We suggest that the bulk stiffening in ZrMo₂ confines the corresponding hydride expansion and thus reduces the H-H elastic interaction. Full article

(This article belongs to the Special Issue State-of-the-Art and Progress in Metal-Hydrogen Systems)

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Open AccessArticle

Oxidation of Phospholipids by OH Radical Coordinated to Copper Amyloid-β Peptide—A Density Functional Theory Modeling

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Inorganics 2023, 11(6), 227; https://doi.org/10.3390/inorganics11060227 - 25 May 2023

Abstract

Oxidative stress and metal dyshomeostasis are considered crucial factors in the pathogenesis of Alzheimer’s disease (AD). Indeed, transition metal ions such as Cu(II) can generate reactive oxygen species (ROS) via O₂ Fenton-like reduction, catalyzed by Cu(II) coordinated to the amyloid-beta (Aβ) peptide. [...] Read more.

Oxidative stress and metal dyshomeostasis are considered crucial factors in the pathogenesis of Alzheimer’s disease (AD). Indeed, transition metal ions such as Cu(II) can generate reactive oxygen species (ROS) via O₂ Fenton-like reduction, catalyzed by Cu(II) coordinated to the amyloid-beta (Aβ) peptide. Despite intensive efforts, the mechanisms of ROS-induced molecular damage remain poorly understood. In the present paper, we investigate, on the basis of Density Functional Theory (DFT) computations, a possible mechanism of the OH radical propagation toward membrane phospholipid polar head and fatty acid chains starting from the end-product of the OH radical generation by Cu(II)-Aβ. Using phosphatidylcholine as a model of a single unit inside a membrane, we evaluated the thermochemistry of the OH propagation with the oxidation of a C-H bond and the formation of the radical moiety. The DFT results show that Cu(II)-Aβ-OH can oxidize only sn-2 C-H bonds of the polar head and can easily oxidize the C-H bond adjacent to the carbon–carbon double bond in a mono or bis unsaturated fatty acid chain. These results are discussed on the basis of the recent literature on in vitro Aβ metal-catalyzed oxidation and on the possible implications in the AD oxidative stress mechanism. Full article

(This article belongs to the Special Issue Editorial Board Members’ Collection Series in “Bioinorganic Chemistry of Copper”)

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Open AccessArticle

Dual-Exciting Central Carbon Nanoclusters for the Dual-Channel Detection of Hemin

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Inorganics 2023, 11(6), 226; https://doi.org/10.3390/inorganics11060226 - 25 May 2023

Abstract

Constructing optical nanoprobes with superior performance is highly desirable for sensitive and accurate assays. Herein, we develop a facile room-temperature strategy for the fabrication of green emissive carbon nanoclusters (CNCs) with dual-exciting centers for the dual-channel sensing of hemin. The formation of the [...] Read more.

Constructing optical nanoprobes with superior performance is highly desirable for sensitive and accurate assays. Herein, we develop a facile room-temperature strategy for the fabrication of green emissive carbon nanoclusters (CNCs) with dual-exciting centers for the dual-channel sensing of hemin. The formation of the CNCs is attributed to the crosslinking polymerization of the precursors driven by the Schiff base reaction between ethylenediamine and 2,3-dichloro-5,6-dicyano-1,4-benzoquinone. Most importantly, the proposed CNCs have a unique excitation-independent green emission (518 nm) with two excitation centers at 260 nm (channel 1) and 410 nm (channel 2). The dual-exciting central emission can serve as dual-channel fluorescence (FL) signals for highly sensitive and reliable detection of hemin based on the inner filter effect. Because of the great spectral overlap difference between the absorption spectrum of hemin and the excitation lights of the CNCs in the two channels, hemin has a different quenching effect on FL emission from different channels. The dual-channel signals of the CNCs can detect hemin in the range of 0.075–10 μM (channel 1) and 0.25–10 μM (channel 2), respectively. These findings not only offer new guidance for the facile synthesis of dual-exciting central CNCs but also establish a reliable sensing platform for the analysis of hemin in complex matrixes. Full article

(This article belongs to the Special Issue Synthesis and Application of Luminescent Materials)

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