Inorganics

11 pages, 1866 KiB

Open AccessArticle

A New Perspective on Fluorapatite Dissolution in Hydrochloric Acid: Thermodynamic Calculations and Experimental Study

by Kaia Tõnsuaadu, Juha Kallas, Rein Kuusik, Gizem Hacialioglu-Erlenheim and Andres Trikkel

Inorganics 2021, 9(8), 65; https://doi.org/10.3390/inorganics9080065 - 16 Aug 2021

Cited by 5 | Viewed by 2384

Apatite (Ap) dissolution in diluted acids is well described in the literature, but in technological processes which use more concentrated acids, the reaction is fast, and it is complicated to follow the process kinetics. The relationship between pH change and the apatite dissolution [...] Read more.

Apatite (Ap) dissolution in diluted acids is well described in the literature, but in technological processes which use more concentrated acids, the reaction is fast, and it is complicated to follow the process kinetics. The relationship between pH change and the apatite dissolution rate depending on HCl concentration was studied by thermodynamic calculations and experiments with synthetic fluorapatite (FAp). On the basis of experimental pH measurements, the kinetics of dissolution was analyzed. The solution composition (P, Ca, F) was determined by wet chemical methods and the solid part was characterized by XRD and FTIR. It was shown that the amount of HCl needed for FAp dissolution depends on acid concentration. FAp dissolution rate cannot be deduced from solubility data of P, Ca or F as the secondary reactions of CaF₂ and CaHPO₄ formation take place simultaneously. It was found that the Ap dissolution rate can be followed by pH change. Full article

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10 pages, 2566 KiB

Open AccessArticle

Switching the Local Symmetry from D_5h to D_4h for Single-Molecule Magnets by Non-Coordinating Solvents

by Xia-Li Ding, Qian-Cheng Luo, Yuan-Qi Zhai, Qian Zhang, Lei Tian, Xinliang Zhang, Chao Ke, Xu-Feng Zhang, Yi Lv and Yan-Zhen Zheng

Inorganics 2021, 9(8), 64; https://doi.org/10.3390/inorganics9080064 - 16 Aug 2021

Cited by 2 | Viewed by 2322

Abstract

A solvent effect towards the performance of two single-molecule magnets (SMMs) was observed. The tetrahydrofuran and toluene solvents can switch the equatorial coordinated 4-Phenylpyridine (4-PhPy) molecules from five to four, respectively, in [Dy(O^tBu)₂(4-PhPy)₅]BPh₄1 and Na{[Dy(O [...] Read more.

A solvent effect towards the performance of two single-molecule magnets (SMMs) was observed. The tetrahydrofuran and toluene solvents can switch the equatorial coordinated 4-Phenylpyridine (4-PhPy) molecules from five to four, respectively, in [Dy(O^tBu)₂(4-PhPy)₅]BPh₄1 and Na{[Dy(O^tBu)₂(4-PhPy)₄][BPh₄]₂}∙2thf∙hex 2. This alternation significantly changes the local coordination symmetry of the Dy(III) center from D_5h to D_4h for 1 and 2, seperately. Magnetic studies show that the magnetic anisotropy energy barrier of 2 is higher than that of 1, while the relation of blocking temperature is just on the contrary due to the symmetry effect. The calculations of the electrostatic potential successfully explained the driving force of solvents for the molecular structure change, confirming the feasibility of adjusting the performance of SMMs via diverse solvents. Full article

(This article belongs to the Special Issue Lanthanide Single-Molecule Magnets)

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12 pages, 14586 KiB

Open AccessArticle

Effect of Reduced Atmosphere Sintering on Blocking Grain Boundaries in Rare-Earth Doped Ceria

by Soumitra Sulekar, Mehrad Mehr, Ji Hyun Kim and Juan Claudio Nino

Inorganics 2021, 9(8), 63; https://doi.org/10.3390/inorganics9080063 - 09 Aug 2021

Cited by 3 | Viewed by 1915

Abstract

Rare-earth doped ceria materials are amongst the top choices for use in electrolytes and composite electrodes in intermediate temperature solid oxide fuel cells. Trivalent acceptor dopants such as gadolinium, which mediate the ionic conductivity in ceria by creating oxygen vacancies, have a tendency [...] Read more.

Rare-earth doped ceria materials are amongst the top choices for use in electrolytes and composite electrodes in intermediate temperature solid oxide fuel cells. Trivalent acceptor dopants such as gadolinium, which mediate the ionic conductivity in ceria by creating oxygen vacancies, have a tendency to segregate at grain boundaries and triple points. This leads to formation of ionically resistive blocking grain boundaries and necessitates high operating temperatures to overcome this barrier. In an effort to improve the grain boundary conductivity, we studied the effect of a modified sintering cycle, where 10 mol% gadolinia doped ceria was sintered under a reducing atmosphere and subsequently reoxidized. A detailed analysis of the complex impedance, conductivity, and activation energy values was performed. The analysis shows that for samples processed thus, the ionic conductivity improves when compared with conventionally processed samples sintered in air. Equivalent circuit fitting shows that this improvement in conductivity is mainly due to a drop in the grain boundary resistance. Based on comparison of activation energy values for the conventionally processed vs. reduced-reoxidized samples, this drop can be attributed to a diminished blocking effect of defect-associates at the grain boundaries. Full article

(This article belongs to the Special Issue Electroceramic Materials: Composition–Structure–Property Relationships 2021)

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14 pages, 3795 KiB

Open AccessArticle

Barium Titanium Oxynitride from Ammonia-Free Nitridation of Reduced BaTiO₃

by Hua Guo, Aleksander Jaworski, Zheng Chen, Can Lu, Adam Slabon and Ulrich Häussermann

Inorganics 2021, 9(8), 62; https://doi.org/10.3390/inorganics9080062 - 05 Aug 2021

Cited by 3 | Viewed by 2857

Abstract

We investigated the nitridation of reduced BaTiO₃, BaTiO_2.60H_0.08, corresponding to an oxyhydride with a large concentration of O defects (>10%). The material is readily nitrided under flowing N₂ gas at temperatures between 400 and 450 °C [...] Read more.

We investigated the nitridation of reduced BaTiO₃, BaTiO_2.60H_0.08, corresponding to an oxyhydride with a large concentration of O defects (>10%). The material is readily nitrided under flowing N₂ gas at temperatures between 400 and 450 °C to yield oxynitrides BaTiO_2.6N_x (x = 0.2−0.22) with a slightly tetragonally distorted perovskite structure, a ≈ 4.01 and c ≈ 4.02 Å, and Ti partially remaining in the oxidation state III. The tetragonal structure was confirmed from Raman spectroscopy. ¹⁴N MAS NMR spectroscopy shows a single resonance at 270 ppm, which is typical for perovskite transition metal oxynitrides. However, largely different signal intensity for materials with very similar N content suggests N/O/vacancy ordering when prolonging nitridation times to hours. Diffuse reflectance UV-VIS spectroscopy shows a reduction of the intrinsic band gap to 2.4–2.45 eV compared to BaTiO₃ (~3.2 eV). Mott-Schottky measurements confirm n-type conductivity and reveal a slight negative shift of the conduction band edge from –0.59 V (BaTiO₃) to ~–0.65 eV. Full article

(This article belongs to the Section Inorganic Solid-State Chemistry)

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13 pages, 6922 KiB

Open AccessArticle

Testing the Efficacy of the Synthesis of Iron Antimony Sulfide Powders from Single Source Precursors

by Fadiyah Makin, Dalal Alzahrani, Firoz Alam, Floriana Tuna and David J. Lewis

Inorganics 2021, 9(8), 61; https://doi.org/10.3390/inorganics9080061 - 02 Aug 2021

Cited by 4 | Viewed by 2743

Abstract

The antimony-iron sulfide system in general does not produce alloys below 540 °C from traditional solid-state methods. However, single source precursors have been known to produce unexpected products that arise from kinetically trapped polymorphs. In this paper, we test the efficacy of this [...] Read more.

The antimony-iron sulfide system in general does not produce alloys below 540 °C from traditional solid-state methods. However, single source precursors have been known to produce unexpected products that arise from kinetically trapped polymorphs. In this paper, we test the efficacy of this approach toward the Fe-Sb-S system. Antimony and iron diethyldithiocarbamate complexes of the form Sb[S₂CN(Et₂)]₃ (1) and Fe[S₂CN(Et₂)]₃ (2) were synthesised, characterised, and used as single-source precursors for the preparation of Sb₂S₃, Fe_xS_y, and mixed iron antimony sulfide Sb_2(1−x)Fe_2xS₃ (0 ≥ x ≥ 1) powders using the solvent-less thermolysis method at different temperatures ranging from 300 to 475 °C. The effect of different mole fractions of the iron precursor was evaluated on morphology, shape, and optical and magnetic properties of Sb_2(1−x)Fe_2xS₃ (0 ≥ x ≥ 1). The obtained powders were characterized by X-ray diffraction (XRD), Raman spectroscopy scanning electron microscopy (SEM), energy dispersive X-ray (EDX) spectroscopy, magnetometer measurement, and UV/vis/NIR spectroscopy. The results demonstrated that the crystalline structure, morphology, and elemental composition of the samples changed with the mole fraction of the precursor. There was significant phase separation between Sb and Fe sulfides noted from EDX spectroscopic mapping, yet an optoelectronic study monitoring the direct band gap energy of antimony sulfide shows that the band gap energy increases as a function of Fe content, which suggests limited alloying is possible from the single source route. Full article

(This article belongs to the Special Issue Metal Dithiocarbamate Complexes: Versatile Ligands in Coordination Chemistry with Applications in Medicine, Materials Science, and Beyond)

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41 pages, 7723 KiB

Open AccessReview

Dithiocarbamate Complexes of Platinum Group Metals: Structural Aspects and Applications

by Yee Seng Tan, Chien Ing Yeo, Edward R. T. Tiekink and Peter J. Heard

Inorganics 2021, 9(8), 60; https://doi.org/10.3390/inorganics9080060 - 22 Jul 2021

Cited by 23 | Viewed by 4373

Abstract

The incorporation of dithiocarbamate ligands in the preparation of metal complexes is largely prompted by the versatility of this molecule. Fascinating coordination chemistry can be obtained from the study of such metal complexes ranging from their preparation, the solid-state properties, solution behavior as [...] Read more.

The incorporation of dithiocarbamate ligands in the preparation of metal complexes is largely prompted by the versatility of this molecule. Fascinating coordination chemistry can be obtained from the study of such metal complexes ranging from their preparation, the solid-state properties, solution behavior as well as their applications as bioactive materials and luminescent compounds, to name a few. In this overview, the dithiocarbamate complexes of platinum-group elements form the focus of the discussion. The structural aspects of these complexes will be discussed based upon the intriguing findings obtained from their solid- (crystallographic) and solution-state (NMR) studies. At the end of this review, the applications of platinum-group metal complexes will be discussed. Full article

(This article belongs to the Special Issue Metal Dithiocarbamate Complexes: Versatile Ligands in Coordination Chemistry with Applications in Medicine, Materials Science, and Beyond)

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25 pages, 17465 KiB

Open AccessArticle

Synthesis and Antiparasitic Activity of New Conjugates—Organic Drugs Tethered to Trithiolato-Bridged Dinuclear Ruthenium(II)–Arene Complexes

by Oksana Desiatkina, Serena K. Johns, Nicoleta Anghel, Ghalia Boubaker, Andrew Hemphill, Julien Furrer and Emilia Păunescu

Inorganics 2021, 9(8), 59; https://doi.org/10.3390/inorganics9080059 - 21 Jul 2021

Cited by 6 | Viewed by 2944

Abstract

Tethering known drugs to a metalorganic moiety is an efficient approach for modulating the anticancer, antibacterial, and antiparasitic activity of organometallic complexes. This study focused on the synthesis and evaluation of new dinuclear ruthenium(II)–arene compounds linked to several antimicrobial compounds such as dapsone, [...] Read more.

Tethering known drugs to a metalorganic moiety is an efficient approach for modulating the anticancer, antibacterial, and antiparasitic activity of organometallic complexes. This study focused on the synthesis and evaluation of new dinuclear ruthenium(II)–arene compounds linked to several antimicrobial compounds such as dapsone, sulfamethoxazole, sulfadiazine, sulfadoxine, triclosan, metronidazole, ciprofloxacin, as well as menadione (a 1,4-naphtoquinone derivative). In a primary screen, 30 compounds (17 hybrid molecules, diruthenium intermediates, and antimicrobials) were assessed for in vitro activity against transgenic T. gondii tachyzoites constitutively expressing β-galactosidase (T. gondii β-gal) at 0.1 and 1 µM. In parallel, the cytotoxicity in noninfected host cells (human foreskin fibroblasts, HFF) was determined by an alamarBlue assay. When assessed at 1 µM, five compounds strongly impaired parasite proliferation by >90%, and HFF viability was retained at 50% or more, and they were further subjected to T. gondii β-gal dose-response studies. Two compounds, notably 11 and 13, amide and ester conjugates with sulfadoxine and metronidazole, exhibited low IC₅₀ (half-maximal inhibitory concentration) values 0.063 and 0.152 µM, and low or intermediate impairment of HFF viability at 2.5 µM (83 and 64%). The nature of the anchored drug as well as that of the linking unit impacted the biological activity. Full article

(This article belongs to the Special Issue Metal Arene Complexes)

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Inorganics, Volume 9, Issue 8 (August 2021) – 7 articles

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