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Inorganics, Volume 12, Issue 2 (February 2024) – 26 articles

Cover Story (view full-size image): This study introduces the synthesis of novel dicopper-substituted polyoxovanadate [Cu2V16O44(NO3)]5− (Cu2V16). From single-crystal X-ray analysis, Cu2V16 exhibited the same framework with the same guest anion of nitrate-incorporated polyoxovanadate, [V18O46(NO3)]5− (V18). The temperature-dependent IR spectra indicated that the nitrate rotates relatively easily in the polyoxovanadate framework by the substitution of copper atoms instead of (VO)2+ sites in V18. In addition, the catalytic performance for the oxidation of 1-phenyl ethanol to acetophenone was drastically changed by the metal substitution. By taking advantage of the same framework in both catalysts, the most active site is on the substituted copper atoms rather than the polyoxovanadate framework. View this paper
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12 pages, 2434 KiB  
Article
Synthesis of Copper-Substituted Polyoxovanadate and Oxidation of 1-Phenyl Ethanol
by Isshin Yoshida, Ryoji Mitsuhashi, Yuji Kikukawa and Yoshihito Hayashi
Inorganics 2024, 12(2), 61; https://doi.org/10.3390/inorganics12020061 - 19 Feb 2024
Viewed by 853
Abstract
Dicopper-substituted polyoxovanadate [Cu2V16O44(NO3)]5− (Cu2V16) was synthesized through the reaction of [Cu2V8O24]4− and [V4O12]4− in the presence of nitrate salt. From single crystal [...] Read more.
Dicopper-substituted polyoxovanadate [Cu2V16O44(NO3)]5− (Cu2V16) was synthesized through the reaction of [Cu2V8O24]4− and [V4O12]4− in the presence of nitrate salt. From single crystal X-ray analysis, Cu2V16 exhibited the same helical structure as that of nitrate-incorporated polyoxovanadate, [V18O46(NO3)]5− (V18). Both complexes had the same framework with the same guest anion and are considered to be substituted isomers for each other by replacing two Cu2+ ions and two [VO]2+ ions. The incorporated nitrate showed short and long N–O bond lengths (1.14, 1.26 and 1.30 Å) as in the case of V18 (1.09, 1.16 and 1.28 Å). Reflecting the inequivalent bond lengths of the nitrate, the IR spectrum of V18 shows split peaks at 1359 and 1342 cm−1. But the Cu2V16 spectrum showed a single peak due to the presence of nitrate at 1353 cm−1. When the temperature was lowered, the nitrate peak in Cu2V16 was split into two positions at 1354 and 1345 cm−1 when the temperature reached −140 °C. These results indicate that the nitrate incorporated in Cu2V16 rotates relatively easily in the Cu2V16 cavity at room temperature compared to V18. In addition, the oxidation of 1-phenyl ethanol to acetophenone with Cu2V16 smoothly proceeded in comparison with V18. By taking advantage of the same framework in both catalysts, we can deduce the position of potential active sites in the oxidation reaction. We have concluded that the most active site is not on the peripheral of the vanadate framework, but it is reasonable to suggest that the active site is on the substituted copper atoms rather than the polyoxovanadate framework. Full article
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11 pages, 2577 KiB  
Article
Bipolar Plasticity in Synaptic Transistors: Utilizing HfSe2 Channel with Direct-Contact HfO2 Gate Dielectrics
by Jie Lu, Zeyang Xiang, Kexiang Wang, Mengrui Shi, Liuxuan Wu, Fuyu Yan, Ranping Li, Zixuan Wang, Huilin Jin and Ran Jiang
Inorganics 2024, 12(2), 60; https://doi.org/10.3390/inorganics12020060 - 17 Feb 2024
Viewed by 846
Abstract
The investigation of dual-mode synaptic plasticity was conducted in thin-film transistors (TFTs) featuring an HfSe2 channel, coupled with an oxygen-deficient (OD)-HfO2 layer structure. In these transistors, the application of negative gate pulses resulted in a notable increase in the post-synaptic current, [...] Read more.
The investigation of dual-mode synaptic plasticity was conducted in thin-film transistors (TFTs) featuring an HfSe2 channel, coupled with an oxygen-deficient (OD)-HfO2 layer structure. In these transistors, the application of negative gate pulses resulted in a notable increase in the post-synaptic current, while positive pulses led to a decrease. This distinctive response can be attributed to the dynamic interplay of charge interactions, significantly influenced by the ferroelectric characteristics of the OD-HfO2 layer. The findings from this study highlight the capability of this particular TFT configuration in closely mirroring the intricate functionalities of biological neurons, paving the way for advancements in bio-inspired computing technologies. Full article
(This article belongs to the Special Issue Advanced Inorganic Semiconductor Materials)
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12 pages, 5871 KiB  
Article
A First-Principle Study of Two-Dimensional Boron Nitride Polymorph with Tunable Magnetism
by Liping Qiao, Zhongqi Ma, Fulong Yan, Sake Wang and Qingyang Fan
Inorganics 2024, 12(2), 59; https://doi.org/10.3390/inorganics12020059 - 15 Feb 2024
Viewed by 905
Abstract
Using the first-principles calculation, two doping two-dimensional (2D) BN (boron nitride) polymorphs are constructed in this work. The two doping 2D BN polymorphs B5N6Al and B5N6C sheets are thermally stable under 500 K. All the [...] Read more.
Using the first-principles calculation, two doping two-dimensional (2D) BN (boron nitride) polymorphs are constructed in this work. The two doping 2D BN polymorphs B5N6Al and B5N6C sheets are thermally stable under 500 K. All the B6N6, B5N6Al, and B5N6C sheets are semiconductor materials with indirect band gaps on the basis of a hybrid functional. The anisotropic calculation results indicate that Young’s modulus (E) and Poisson’s ratio (v) of the B6N6, B5N6Al, and B5N6C sheets are anisotropic in the xy plane. In addition, the magnetic properties of the B6N6, B5N6Al, and B5N6C sheets have also been investigated. According to the calculation of the magnetic properties, B6N6 sheet does not exhibit magnetism, while it shows weak magnetism after doping carbon atom to the BN sheet. This paper explores the influence mechanism of doping different atoms on the basic physical properties of two-dimensional BN sheets. It not only constructs a relationship between structure and performance but also provides theoretical support for the performance regulation of BN materials. Full article
(This article belongs to the Special Issue Advanced Inorganic Semiconductor Materials)
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11 pages, 960 KiB  
Article
Synthesis and Photophysical Evaluation of Isoleptic Pt(II) and Pd(II) Complexes Utilizing N^N^N Ligands as Luminophoric Chelators with Different Ancillary Ligands
by Silpa Padmakumar Sheelakumari, María Victoria Cappellari, María Belen Rivas Aiello, Alexander Hepp and Cristian Alejandro Strassert
Inorganics 2024, 12(2), 58; https://doi.org/10.3390/inorganics12020058 - 14 Feb 2024
Viewed by 985
Abstract
We herein report on the synthesis and structural characterization, as well as on the photophysical properties, of a series of isoleptic Pt(II) and Pd(II) complexes featuring tridentate N^N^N chelators as luminophores while bearing diverse ancillary co-ligands. Six new palladium complexes were synthesized using [...] Read more.
We herein report on the synthesis and structural characterization, as well as on the photophysical properties, of a series of isoleptic Pt(II) and Pd(II) complexes featuring tridentate N^N^N chelators as luminophores while bearing diverse ancillary co-ligands. Six new palladium complexes were synthesized using 2,6-bis(3-(tert-butyl/trifluoromethyl)-1H-1,2,4-triazol-5-yl)pyridine (tbu or CF3, respectively) in combination with four distinct ancillary ligands, namely: 4-amylpyridine (AmPy), 2,6-dimethylphenyl isonitrile (CNR), triphenylphosphane (PPh3), and 1,3,5-triaza-7-phosphaadamantane (PTA). Thus, two novel Pt(II) complexes incorporating the co-ligands CNR and PTA were explored. The remaining platinum-based complexes, namely CF3-Pt-AmPy, tbu-Pt-AmPy, CF3-Pt-PPh3, and tbu-Pt-PPh3, were re-synthesized according to our previous work for a systematic comparison with their Pd(II) homologues. Thus, photophysical studies were performed in different solvents and conditions. The Pt(II) complexes demonstrated comparable or superior photophysical characteristics in toluene when compared with their solutions in liquid dichloromethane at room temperature. In contrast, the Pd(II) complexes exhibited no significant photoluminescence in dichloromethane, but a surprisingly clear emission was observed for tbu-Pd-AmPy, tbu-Pd-CNR, and tbu-Pd-PPh3 in liquid toluene at room temperature. The significant differences regarding excited state lifetimes and photoluminescence quantum yields underscore the impact of solvent selection on photophysical characteristics, emphasizing the need to consider metal-ligand interactions, as well as the surrounding microenvironment, for a comprehensive interpretation of their photophysical properties. In addition, it is clear that AmPy and CNR render better luminescence efficiencies, whereas PTA is only suitable in toluene. Full article
(This article belongs to the Section Coordination Chemistry)
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14 pages, 4024 KiB  
Article
The Influence of the Cu Foam on the Electrochemical Reduction of Carbon Dioxide
by Yuan-Gee Lee, Hui-Hsuan Chiao, Yu-Ching Weng and Chyi-How Lay
Inorganics 2024, 12(2), 57; https://doi.org/10.3390/inorganics12020057 - 11 Feb 2024
Viewed by 1022
Abstract
Unlike the flat Cu sheet, we employed Cu foam to explore the specific porous effect on the expanding specific area. We found that the foam structure is superior to the sheet feature in the specific location from the morphology investigation. In the practical [...] Read more.
Unlike the flat Cu sheet, we employed Cu foam to explore the specific porous effect on the expanding specific area. We found that the foam structure is superior to the sheet feature in the specific location from the morphology investigation. In the practical measurement of surface area, we found that the adsorbate could aptly agglomerate, resulting in a consequential block in the transport path. The specific location of the Cu foam was underestimated because the channels of the deep foam layer were blocked by the agglomerated adsorbate. To explore the protonation process of the electro-reduction, we adopted the carbonate electrolyte as the control group in contrast to the experimental group, the bicarbonate electrolyte. In the carbonate electrolyte, the primary intermediate was shown to be CO molecules, as verified using XPS spectra. In the bicarbonate electrolyte, the intermediate CO disappeared; instead, it was hydrogenated as a hydrocarbon intermediate, CHO*. The bicarbonate ion was also found to suppress electrocatalysis in the deep structure of the Cu foam because its high-molecular-weight intermediates accumulated in the diffusion paths. Furthermore, we found a promotion of the oxidation valence on the electrode from Cu2O to CuO, when the electrode structure transformed from sheet to foam. Cyclic voltammograms demonstrate a succession of electro-reduction consequences: at low reduction potential, hydrogen liberated by the decomposition of water; at elevated reduction potential, formic acid and CO produced; and at high reduction potential, CH4 and C2H4 were formed from −1.4 V to −1.8 V. Full article
(This article belongs to the Section Inorganic Materials)
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12 pages, 6768 KiB  
Article
Theoretical Study on the Structures and Stabilities of CunZn3O3 (n = 1–4) Clusters: Sequential Doping of Zn3O3 Cluster with Cu Atoms
by Zhi-Wei Tao, Han-Yi Zou, Hong-Hui Li, Bin Wang and Wen-Jie Chen
Inorganics 2024, 12(2), 56; https://doi.org/10.3390/inorganics12020056 - 09 Feb 2024
Viewed by 987
Abstract
Density functional theory (DFT) and coupled cluster theory (CCSD(T)) calculations are performed to investigate the geometric and electronic structures and chemical bonding of a series of Cu-doped zinc oxide clusters: CunZn3O3 (n = 1–4). The structural evolution [...] Read more.
Density functional theory (DFT) and coupled cluster theory (CCSD(T)) calculations are performed to investigate the geometric and electronic structures and chemical bonding of a series of Cu-doped zinc oxide clusters: CunZn3O3 (n = 1–4). The structural evolution of CunZn3O3 (n = 1–4) clusters may reveal the aggregation behavior of Cu atoms on the Zn3O3 cluster. The planar seven-membered ring of the CuZn3O3 cluster plays an important role in the structural evolution; that is, the Cu atom, Cu dimer (Cu2) and Cu trimer (Cu3) anchor on the CuZn3O3 cluster. Additionally, it is found that CunZn3O3 clusters become more stable as the Cu content (n) increases. Bader charge analysis points out that with the doping of Cu atoms, the reducibility of Cu aggregation (Cun−1) on the CuZn3O3 cluster increases. Combined with the d-band centers and the surface electrostatic potential (ESP), the reactivity and the possible reaction sites of CunZn3O3 (n = 1–4) clusters are also illustrated. Full article
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13 pages, 2152 KiB  
Article
Structural Evolution and Hydrogen Sorption Properties of YxNi2−yMny (0.825 ≤ x ≤ 0.95, 0.1 ≤ y ≤ 0.3) Laves Phase Compounds
by Hao Shen, Valerie Paul-Boncour, Ping Li, Lijun Jiang and Junxian Zhang
Inorganics 2024, 12(2), 55; https://doi.org/10.3390/inorganics12020055 - 07 Feb 2024
Viewed by 909
Abstract
The YxNi2−yMny system was investigated in the region 0.825 ≤ x ≤ 0.95, 0.1 ≤ y ≤ 0.3. The alloys were synthesized by induction melting and corresponding annealing. The substitution of Mn for Ni (y = [...] Read more.
The YxNi2−yMny system was investigated in the region 0.825 ≤ x ≤ 0.95, 0.1 ≤ y ≤ 0.3. The alloys were synthesized by induction melting and corresponding annealing. The substitution of Mn for Ni (y = 0.1) favors the formation of a C15 structure with disordered Y vacancies against the superstructure of Y0.95Ni2. For y = 0.2 and 0.3, Mn can substitute in both Y and Ni sites. Single-phase compounds with a C15 structure can be formed by adjusting both the Y and Mn contents. Their hydrogen absorption–desorption properties were measured by pressure–composition isotherm (PCI) measurements at 150 °C, and the hydrides were characterized at room temperature by X-ray diffraction and TG–DSC experiments. The PCIs show two plateaus corresponding to the formation of crystalline and amorphous hydrides. The heating of the amorphous hydrides leads to an endothermic desorption at first and then a recrystallization into Y(Ni, Mn)3 and YHx phases. At higher temperatures, the Y hydride desorbs, and a recombination into a Y(Ni, Mn)2 Laves phase compound is observed. For y = 0.1, vacancy formation in the Y site and partial Mn substitution in the Ni site enhance the structural stability and suppress the hydrogen-induced amorphization (HIA). However, for a larger Mn content (y ≥ 0.2), Mn substitutes also in the Y sites at the expense of Y vacancies. This yields worse structural stability upon hydrogenation than for y = 0.1, as the mean ratio r(Y, Mn)/r(Ni/Mn) becomes larger than for y = 0.1 r(Y, ☐)/r(Ni/Mn). Full article
(This article belongs to the Special Issue 10th Anniversary of Inorganics: Inorganic Solid State Chemistry)
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28 pages, 4780 KiB  
Review
Mechanochemical Synthesis of Solid-State Electrolytes
by Sanja Burazer and Jasminka Popović
Inorganics 2024, 12(2), 54; https://doi.org/10.3390/inorganics12020054 - 06 Feb 2024
Viewed by 1515
Abstract
In recent decades, the field of materials research has put significant emphasis on developing innovative platforms that have the potential to address the increasing global energy demand. Batteries have demonstrated their enormous effectiveness in the context of energy storage and consumption. However, safety [...] Read more.
In recent decades, the field of materials research has put significant emphasis on developing innovative platforms that have the potential to address the increasing global energy demand. Batteries have demonstrated their enormous effectiveness in the context of energy storage and consumption. However, safety issues associated with liquid electrolytes combined with a low abundance of lithium in the Earth’s crust gave rise to the development of solid-state electrolytes and cations other than lithium. The commercial production of solid-state batteries demands the scaling up of solid-state electrolyte syntheses as well as the mixing of electrode composites containing solid electrolytes. This review is motivated by the recent literature, and it gives a thorough overview of solid-state electrolytes and highlights the significance of the employed milling and dispersing procedures for the resulting ionic transport properties. Full article
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13 pages, 3941 KiB  
Article
Effect of Sintering Time and Cl Doping Concentrations on Structural, Optical, and Luminescence Properties of ZnO Nanoparticles
by Arshad Khan, Soheir E. Mohamed, Tayseer I. Al-Naggar, Hasan B. Albargi, Jari S. Algethami and Ayman M. Abdalla
Inorganics 2024, 12(2), 53; https://doi.org/10.3390/inorganics12020053 - 04 Feb 2024
Cited by 1 | Viewed by 1129
Abstract
Zinc oxide (ZnO) nanoparticles were synthesized hydrothermally using zinc acetate dihydrate and sodium thiosulfate pentahydrate precursors. The synthesized powders were sintered in air at 600 °C for different durations with a Cl-doping concentration of 25 mg/g. The optimal sintering time was found to [...] Read more.
Zinc oxide (ZnO) nanoparticles were synthesized hydrothermally using zinc acetate dihydrate and sodium thiosulfate pentahydrate precursors. The synthesized powders were sintered in air at 600 °C for different durations with a Cl-doping concentration of 25 mg/g. The optimal sintering time was found to be 5 h, resulting in the successful formation of the ZnO phase with small particle sizes of around 90 nm, nominal atomic fractions of Zn and O (~50%, ~50%), and increased luminescence intensity. The ideal concentration of Cl was discovered to be 25 mg/g of ZnO, which resulted in the highest luminescence intensity. The ZnO luminescence characteristics were observed in emission bands peaking at approximately 503 nm attributed to the transition from oxygen vacancies. A considerable improvement in the emission intensity was observed with increased Cl doping concentration, up to eight orders of magnitude, compared to pristine ZnO nanoparticles. However, the luminescence intensity decreased in samples with higher concentrations of Cl doping due to concentration quenching. These preliminary outcomes suggest that Cl-doped ZnO nanoparticles could be used for radiation detector development for radon monitoring and other related applications. Full article
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25 pages, 4282 KiB  
Review
Chemical Stability of Metal Halide Perovskite Detectors
by Bin Zhang, Bin Xue, Shuang Xiao and Xingzhu Wang
Inorganics 2024, 12(2), 52; https://doi.org/10.3390/inorganics12020052 - 03 Feb 2024
Viewed by 1237
Abstract
Metal halide perovskite (MHP) detectors are highly esteemed for their outstanding photoelectric properties and versatility in applications. However, they are unfortunately prone to degradation, which constitutes a significant barrier to their sustained performance. This review meticulously delves into the causes leading to their [...] Read more.
Metal halide perovskite (MHP) detectors are highly esteemed for their outstanding photoelectric properties and versatility in applications. However, they are unfortunately prone to degradation, which constitutes a significant barrier to their sustained performance. This review meticulously delves into the causes leading to their instability, predominantly attributable to factors such as humidity, temperature, and electric fields and, notably, to various radiation factors such as X-rays, γ-rays, electron beams, and proton beams. Furthermore, it outlines recent advancements in strategies aimed at mitigating these detrimental effects, emphasizing breakthroughs in composition engineering, heterostructure construction, and encapsulation methodologies. At last, this review underscores the needs for future improvements in theoretical studies, material design, and standard testing protocols. In the pursuit of optimizing the chemical stability of MHP detectors, collaborative efforts are in an imperative need. In this way, broad industrial applications of MHP detectors could be achieved. Full article
(This article belongs to the Section Organometallic Chemistry)
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19 pages, 3030 KiB  
Article
ZnO–Doped CaO Binary Core–Shell Catalysts for Biodiesel Production via Mexican Palm Oil Transesterification
by M. G. Arenas-Quevedo, M. E. Manríquez, J. A. Wang, O. Elizalde-Solís, J. González-García, A. Zúñiga-Moreno and L. F. Chen
Inorganics 2024, 12(2), 51; https://doi.org/10.3390/inorganics12020051 - 03 Feb 2024
Viewed by 1142
Abstract
This work investigates biodiesel production via transesterification of Mexican palm oil with methanol catalyzed by binary solid base core–shell catalysts with improved catalytic stability. A series of CaO–ZnO mixed solids were prepared using an inexpensive co–precipitation method by varying ZnO content from 5 [...] Read more.
This work investigates biodiesel production via transesterification of Mexican palm oil with methanol catalyzed by binary solid base core–shell catalysts with improved catalytic stability. A series of CaO–ZnO mixed solids were prepared using an inexpensive co–precipitation method by varying ZnO content from 5 to 20 mol%. Several factors, such as surface basicity, ZnO content, phase compositions, and thermal treatment of the catalysts, were all proven to be crucial for the production of biodiesel with good quality. Thermal treatment could effectively remove the surface adsorbed water and impurities and improved the catalytic activity. The addition of ZnO to CaO significantly enhanced the catalysts’ stability; however, it led to lower surface basicity and slightly diminished catalytic activity. ZnO doping inhibited the formation of surface Ca(OH)2 and promoted the formation of Ca–Zn–O or CaZn2(OH)6 phase as the core and a surface CaCO3 shell, which effectively decreased Ca2+ leaching by approximately 74% in methanol and 65% in a methanol–glycerol (4:1) mixture. A combined method of separation and purification for obtaining clean biodiesel with high quality was proposed. The biodiesel obtained under the control conditions exhibited properties which satisfied the corresponding standards well. Full article
(This article belongs to the Special Issue 10th Anniversary of Inorganics: Inorganic Materials)
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23 pages, 14000 KiB  
Review
Application of Infrared Free-Electron Laser Irradiation of Protein Complexes Binding to Salen-Type Schiff Base Zn(II) Complexes Using Secondary Conformational Changes in the Proteins for the Treatment of Alzheimer’s Disease
by Hiroshi Takashima, Daisuke Nakane and Takashiro Akitsu
Inorganics 2024, 12(2), 50; https://doi.org/10.3390/inorganics12020050 - 03 Feb 2024
Viewed by 1317
Abstract
Alzheimer’s disease causes the destruction of cranial nerve cells and is said to be caused by neuronal cell death due to the accumulation of amyloid-β protein. One method for the treatment of Alzheimer’s disease is to reduce the toxicity of the amyloid beta [...] Read more.
Alzheimer’s disease causes the destruction of cranial nerve cells and is said to be caused by neuronal cell death due to the accumulation of amyloid-β protein. One method for the treatment of Alzheimer’s disease is to reduce the toxicity of the amyloid beta protein. Among the possibilities is to reduce toxicity by changing the secondary structure of the protein. In this study, the secondary structure of the protein was verified by binding a zinc complex to the protein and irradiating it with an infrared free-electron laser (IR-FEL). By binding Salen-Type zinc complexes to human serum albumin (HSA) and irradiating it with IR-FEL, structural changes were observed in the α-helix and β-sheet, the secondary structure of HSA. In addition to researching the possibility of binding zinc complexes to small proteins, docking simulations were examined. GOLD docking simulations showed that it is possible to bind zinc complexes to lysozyme (Lyz), a small protein. These results suggest that binding zinc complexes to amyloid-β and inducing a secondary conformational change through IR-FEL irradiation could be used for the treatment of Alzheimer’s disease by making the complexes lose their toxicity. Full article
(This article belongs to the Special Issue Rational Design of Pharmacologically Active Metal-Based Compounds)
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21 pages, 5733 KiB  
Article
Comparative Solution Equilibrium Studies on Anticancer Estradiol-Based Conjugates and Their Copper Complexes
by Éva A. Enyedy, Anett Giricz, Tatsiana V. Petrasheuskaya, János P. Mészáros, Nóra V. May, Gabriella Spengler, Ferenc Kovács, Barnabás Molnár and Éva Frank
Inorganics 2024, 12(2), 49; https://doi.org/10.3390/inorganics12020049 - 01 Feb 2024
Viewed by 1241
Abstract
Steroids are often considered valuable molecular tools for the development of anticancer agents with improved pharmacological properties. Conjugation of metal chelating moieties with a lipophilic sterane backbone is a viable option to obtain novel anticancer compounds. In this work, two estradiol-based hybrid molecules [...] Read more.
Steroids are often considered valuable molecular tools for the development of anticancer agents with improved pharmacological properties. Conjugation of metal chelating moieties with a lipophilic sterane backbone is a viable option to obtain novel anticancer compounds. In this work, two estradiol-based hybrid molecules (PMA-E2 and DMA-E2) with an (N,N,O) binding motif and their Cu(II) complexes were developed. The lipophilicity, solubility, and acid-base properties of the novel ligands were determined by the combined use of UV-visible spectrophotometry, pH-potentiometry, and 1H NMR spectroscopy. The solution speciation and redox activity of the Cu(II) complexes were also investigated by means of UV-visible and electron paramagnetic resonance spectroscopy. Two structurally analogous ligands (PMAP and DMAP) were also included in the studies for better interpretation of the solution chemical data obtained. Three pKa values were determined for all ligands, revealing the order of the deprotonation steps: pyridinium-NH+ or NH(CH3)2+, secondary NH2+, and OH. The dimethylamine derivatives (DMA-E2, DMAP) are found in their H2L+ forms in solution at pH 7.4, whereas the fraction of the neutral HL species is significant (34–37%) in the case of the pyridine nitrogen-containing derivatives (PMA-E2, PMAP). Both estradiol derivatives were moderately cytotoxic in human breast (MCF-7) and colon adenocarcinoma (Colo-205) cells (IC50 = 30–63 μM). They form highly stable complexes with Cu(II) ions capable of oxidizing ascorbate and glutathione. These Cu(II) complexes are somewhat more cytotoxic (IC50 = 15–45 μM) than their corresponding ligands and show a better selectivity profile. Full article
(This article belongs to the Special Issue Metal-Based Compounds: Relevance for the Biomedical Field)
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15 pages, 2248 KiB  
Review
Capturing Unstable Metallofullerenes
by Fupin Liu and Alexey A. Popov
Inorganics 2024, 12(2), 48; https://doi.org/10.3390/inorganics12020048 - 31 Jan 2024
Viewed by 1114
Abstract
Metallofullerenes are interesting molecules with unique structures and physicochemical properties. After they are formed in the arc-discharge process, they are first buried in the carbon soot, which requires solvent extraction to fish them out, normally followed by HPLC separation. In this minireview, we [...] Read more.
Metallofullerenes are interesting molecules with unique structures and physicochemical properties. After they are formed in the arc-discharge process, they are first buried in the carbon soot, which requires solvent extraction to fish them out, normally followed by HPLC separation. In this minireview, we summarize the main procedures developed to obtain pure metallofullerenes, including well-established extraction with conventional fullerene solvents followed by HPLC (procedure (I) as well as several methods developed for isolation and purification of unstable fullerenes insoluble in conventional fullerene solvents, including chemical modification followed by dissolution (II.1), chemical functionalization during extraction followed by HPLC (II.2), and chemical functionalization of ionic EMFs after redox-extraction followed by HPLC (procedure II.3). The main focus here is on procedure II.3, for which the current status and future perspective are discussed. Full article
(This article belongs to the Special Issue Research on Metallofullerenes)
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13 pages, 2828 KiB  
Article
Hyperthermia and Photocatalytic Performance of Magnetic Polyvinyl Alcohol under External Magnetic Field
by Manal M. Khowdiary, Hind Alsnani and Mohamed S. A. Darwish
Inorganics 2024, 12(2), 47; https://doi.org/10.3390/inorganics12020047 - 30 Jan 2024
Viewed by 1204
Abstract
The promising physical and chemical properties of components of magnetic polymers could enable extending their intelligent behaviors to material applications. Indeed, investigation into magnetic nanofillers to ensure their uniform dispersion within the polymer matrix remains a great challenge at present. In this work, [...] Read more.
The promising physical and chemical properties of components of magnetic polymers could enable extending their intelligent behaviors to material applications. Indeed, investigation into magnetic nanofillers to ensure their uniform dispersion within the polymer matrix remains a great challenge at present. In this work, polyvinyl alcohol-stabilized iron oxide nanoparticles (PVA@IONPs) were prepared using ultrasonic-assisted coprecipitation at room temperature. It is possible to produce PVA@IONPs with desirable shapes and sizes, which would enable the control of their hyperthermia and photocatalytic performance under an external magnetic field. The saturation magnetization of PVA@IONPs (45.08 emu g−1) was enhanced to the level of IONPs (41.93 emu g−1). The PVA@IONPs showed good photocatalytic and outstanding self-heating behavior. The hydrogen yield was 60 mmole min−1 g−1 for photocatalyst PVA@IONPs under visible light with magnetic force. In addition, the PVA@IONPs exhibited a higher specific absorption rate (SAR) than IONPs under the same magnetic field conditions. The PVA@IONPs displayed superior self-heating and photocatalytic performances, rendering them appropriate materials for biomedical and environmental applications. Full article
(This article belongs to the Special Issue Magnetic Materials and Their Applications)
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18 pages, 4425 KiB  
Article
Investigations of the Influence of Two Pyridyl-Mesoionic Carbene Constitutional Isomers on the Electrochemical and Spectroelectrochemical Properties of Group 6 Metal Carbonyl Complexes
by Tobias Bens and Biprajit Sarkar
Inorganics 2024, 12(2), 46; https://doi.org/10.3390/inorganics12020046 - 29 Jan 2024
Viewed by 1099
Abstract
Metal complexes of mesoionic carbenes (MICs) of the triazolylidene type and their derivatives have gained increasing attention in the fields of electrocatalysis and photochemistry. The redox activity of these metal complexes is critical for their applications in both the aforementioned fields. Easy accessibility [...] Read more.
Metal complexes of mesoionic carbenes (MICs) of the triazolylidene type and their derivatives have gained increasing attention in the fields of electrocatalysis and photochemistry. The redox activity of these metal complexes is critical for their applications in both the aforementioned fields. Easy accessibility and modular synthesis open a wide field for the design of ligands, such as bidentate ligands. The combination of an MIC with a pyridyl unit in a bidentate ligand setup increases the π acceptor properties of the ligands while retaining their strong σ donor properties. The analogy with the well-established 2,2′-bipyridine ligand allows conclusions to be drawn about the influence of the mesoionic carbene (MIC) moiety in tetracarbonyl group 6 complexes in cyclic voltammetry and (spectro)electrochemistry (SEC). However, the effects of the different connectivity in pyridyl-MIC ligands remain underexplored. Based on our previous studies, we present a thorough investigation of the influence of the two different pyridyl-MIC constitutional isomers on the electrochemical and the UV-vis-NIR/IR/EPR spectroelectrochemical properties of group 6 carbonyl complexes. Moreover, the presented complexes were investigated for the electrochemical conversion of CO2 using two different working electrodes, providing a fundamental understanding of the influence of the electrode material in the precatalytic activation. Full article
(This article belongs to the Special Issue 10th Anniversary of Inorganics: Organometallic Chemistry)
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12 pages, 1784 KiB  
Article
Stability and Electronic Properties of 1D and 2D Ca@C60 Oligomers and Polymers
by Yabei Wu, Zhonghao Zhou and Zhiyong Wang
Inorganics 2024, 12(2), 45; https://doi.org/10.3390/inorganics12020045 - 29 Jan 2024
Viewed by 1113
Abstract
The polymerization of fullerenes is a significant method for obtaining fullerene-based materials that possess intriguing properties. Metallofullerenes, as a notable type of fullerene derivatives, are also capable of undergoing polymerization, potentially resulting in the creation of metallofullerene polymers. However, there is currently limited [...] Read more.
The polymerization of fullerenes is a significant method for obtaining fullerene-based materials that possess intriguing properties. Metallofullerenes, as a notable type of fullerene derivatives, are also capable of undergoing polymerization, potentially resulting in the creation of metallofullerene polymers. However, there is currently limited knowledge regarding the polymerization process of metallofullerenes. In this study, we have selected Ca@C 60 as a representative compound to investigate the polymerization process of metallofullerenes. The objective of this research is to determine whether the polymerization process is energetically favorable and to examine how the electronic properties of the metallofullerene are altered throughout the polymerization process. Ca@C 60 is a unique metallofullerene molecule that exhibits insolubility in common fullerene solvents like toluene and carbon disulfide but is soluble in aniline. This behavior suggests a potential tendency for Ca@C 60 to form oligomers and polymers that resist dissolution. However, the structures and properties of polymerized Ca@C 60 remain unknown. We employed density functional theory calculations to investigate the stability and electronic properties of one-dimensional and two-dimensional Ca@C 60 oligomers and polymers. Our findings indicate that the coalescence of Ca@C 60 monomers is energetically favorable, with a significant contribution from van der Waals interactions between the fullerene cages. The polymerization process of Ca@C 60 also involves the formation of covalent linkages, including four-atom rings and C-C single bonds. The increase in the number of the Ca@C 60 units to three and four in the oligomer leads to a significant decrease in the HOMO-LUMO gap. In the two-dimensional polymerized Ca@C 60, the organization of the monomers closely resembles the spatial configuration of carbon atoms in graphene. With a direct bandgap of 0.22 eV, the polymerized Ca@C 60 holds potential for utilization in optoelectronic devices. Full article
(This article belongs to the Special Issue Research on Metallofullerenes)
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14 pages, 2870 KiB  
Article
The Effect of the Linking Unit on the Electronic and Magnetic Interactions in Copper(II) Porphyrin Dimers Linked by Metal Ions
by Jordan L. Appleton, Nolwenn Le Breton, Sylvie Choua and Romain Ruppert
Inorganics 2024, 12(2), 44; https://doi.org/10.3390/inorganics12020044 - 27 Jan 2024
Viewed by 1043
Abstract
The syntheses of a series of copper(II) porphyrins and their dimers linked by palladium(II) or platinum(II) are reported. Their electronic properties and their magnetic properties were studied. In particular, the effect of the linking unit on these properties was evaluated. It was discovered [...] Read more.
The syntheses of a series of copper(II) porphyrins and their dimers linked by palladium(II) or platinum(II) are reported. Their electronic properties and their magnetic properties were studied. In particular, the effect of the linking unit on these properties was evaluated. It was discovered that three factors influence the electronic and magnetic interactions between the two metalloporphyrins: the nature of the linking metal ion, the nature of the external coordination site of the porphyrin, and also the nature of the metal ion present in the central core of the aromatic macrocycle. Full article
(This article belongs to the Special Issue Magnetic Materials and Their Applications)
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10 pages, 1854 KiB  
Article
Structural and Mechanical Properties of NbN Alloyed with Hf, In, and Zr for Orthopedic Applications: A First-Principles Study
by Adel Bandar Alruqi and Nicholas O. Ongwen
Inorganics 2024, 12(2), 43; https://doi.org/10.3390/inorganics12020043 - 27 Jan 2024
Viewed by 1052
Abstract
The search for biocompatible, non-toxic, and wear-resistant materials for orthopedic implant applications is on the rise. Different materials have been investigated for this purpose, some of which have proved successful. However, one challenge that has proven difficult to overcome is the balance between [...] Read more.
The search for biocompatible, non-toxic, and wear-resistant materials for orthopedic implant applications is on the rise. Different materials have been investigated for this purpose, some of which have proved successful. However, one challenge that has proven difficult to overcome is the balance between ductility and hardness of these materials. This study employed ab initio calculations to investigate the structural and mechanical properties of niobium nitride (NbN) alloyed with hafnium, indium, and zirconium, with the aim of improving its hardness. The calculations made use of density function theory within the quantum espresso package’s generalized gradient approximation, with Perdew–Burke–Ernzerhof ultrasoft pseudopotentials in all the calculations. It was found that addition of the three metals led to an improvement in both the shear and Young’s moduli of the alloys compared to those of the NbN. However, both the bulk moduli and the Poisson’s ratios reduced with the introduction of the metals. The Young’s moduli of all the samples were found to be higher than that of bone. The Vickers hardness of the alloys were found to be significantly higher than that of NbN, with that of indium being the highest. The alloys are therefore good for wear-resistant artificial bone implants in ceramic acetabulum, and also in prosthetic heads. Full article
(This article belongs to the Section Inorganic Materials)
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13 pages, 6616 KiB  
Article
A Core and Valence-Level Spectroscopy Study of the Enhanced Reduction of CeO2 by Iron Substitution—Implications for the Thermal Water-Splitting Reaction
by Hicham Idriss
Inorganics 2024, 12(2), 42; https://doi.org/10.3390/inorganics12020042 - 27 Jan 2024
Cited by 1 | Viewed by 1152
Abstract
The reduction of Ce cations in CeO2 can be enhanced by their partial substitution with Fe cations. The enhanced reduction of Ce cations results in a considerable increase in the reaction rates for the thermal water-splitting reaction when compared to CeO2 [...] Read more.
The reduction of Ce cations in CeO2 can be enhanced by their partial substitution with Fe cations. The enhanced reduction of Ce cations results in a considerable increase in the reaction rates for the thermal water-splitting reaction when compared to CeO2 alone. This mixed oxide has a smaller crystallite size when compared to CeO2, in addition to a smaller lattice size. In this work, two Fe-substituted Ce oxides are studied (Ce0.95Fe0.05O2-δ and Ce0.75Fe0.25O2-δ; δ < 0.5) by core and valence level spectroscopy in their as-prepared and Ar-ion-sputtered states. Ar ion sputtering substantially increases Ce4f lines at about 1.5 eV below the Fermi level. In addition, it is found that the XPS Ce5p/O2s ratio is sensitive to the degree of reduction, most likely due to a higher charge transfer from the oxygen to Ce ions upon reduction. Quantitatively, it is also found that XPS Ce3d of the fraction of Ce3+ (uo, u′ and vo, v′) formed upon Ar ion sputtering and the ratio of Ce5p/O2s lines are higher for reduced Ce0.95Fe0.05O2-δ than for reduced Ce0.75Fe0.25O2-δ. XPS Fe2p showed, however, no preferential increase for Fe3+ reduction to Fe0 with increasing time for both oxides. Since water splitting was higher on Ce0.95Fe0.05O2-δ when compared to Ce0.75Fe0.25O2-δ, it is inferred that the reaction centers for the thermal water splitting to hydrogen are the reduced Ce cations and not the reduced Fe cations. These reduced Ce cations can be tracked by their XPS Ce5p/O2s ratio in addition to the common XPS Ce3d lines. Full article
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13 pages, 3692 KiB  
Article
Ferrocene-Bearing Homoleptic and Heteroleptic Paddlewheel-Type Dirhodium Complexes
by Yusuke Kataoka, Kozo Sato, Natsumi Yano and Makoto Handa
Inorganics 2024, 12(2), 41; https://doi.org/10.3390/inorganics12020041 - 26 Jan 2024
Viewed by 1142
Abstract
Two ferrocenecarboxylate (fca)-bridged dirhodium (Rh2) complexes, [Rh2(fca)4] (1) and [Rh2(fca)(piv)3] (2; piv = pivalate), were prepared through the carboxylate-exchange reactions of [Rh2(O2CCH3)4 [...] Read more.
Two ferrocenecarboxylate (fca)-bridged dirhodium (Rh2) complexes, [Rh2(fca)4] (1) and [Rh2(fca)(piv)3] (2; piv = pivalate), were prepared through the carboxylate-exchange reactions of [Rh2(O2CCH3)4(H2O)2] and [Rh2(piv)4], respectively, with fcaH and characterized by 1H NMR, ESI-TOF-MS, and elemental analyses. Single-crystal X-ray diffraction analyses of [Rh2(fca)4(MeOH)2] (1(MeOH)2) and [Rh2(fca)(piv)3(MeOH)2] (2(MeOH)2), which are recrystallized from MeOH-containing solutions of 1 and 2, revealed that (1) 1(MeOH)2 and 2(MeOH)2 possess homoleptic and heteroleptic paddlewheel-type dinuclear structures, respectively; (2) both complexes have a single Rh–Rh bond (2.3771(3) Å for 1(MeOH)2, 2.3712(3) Å for 2(MeOH)2); and (3) the cyclopentadienyl rings of the fca ligands in 1(MeOH)2 adopt an eclipsed conformation, whereas those in 2(MeOH)2 are approximately 12–14° rotated from the staggered conformation. Density functional theory (DFT) calculations revealed that (1) the electronic configurations of the Rh2 core in 1(MeOH)2 and 2(MeOH)2 are π4σ2δ2π*2δ*2π*2 and π4σ2δ2δ*2π*4, respectively; and (2) the occupied molecular orbitals (MOs) localized on the fca ligands are energetically degenerate and relatively more unstable than those on the Rh2 cores. Absorption features and electrochemical properties of 1 and 2 were investigated in a 9:1 CHCl3-MeOH solution and compared with those of fcaH and [Rh2(piv)4]. Through examining the obtained results in detail using time-dependent DFT (TDDFT) and unrestricted DFT, we found that 1 and 2 exhibit charge transfer excitations between the fca ligands and Rh2 cores, and 1 shows electronic interactions between ferrocene units through the Rh2 core in the electrochemical oxidation process. Full article
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12 pages, 2944 KiB  
Article
Geometries, Electronic Structures, Bonding Properties, and Stability Strategy of Endohedral Metallofullerenes TM@C28 (TM = Sc, Y, La, Ti, Zr, Hf, V+, Nb+, Ta+)
by Dong Liu, Yuan Shui and Tao Yang
Inorganics 2024, 12(2), 40; https://doi.org/10.3390/inorganics12020040 - 25 Jan 2024
Viewed by 986
Abstract
We performed quantum chemical calculations on the geometries, electronic structures, bonding properties, and stability strategy of endohedral metallofullerenes TM@C28 (TM = Sc, Y, La, Ti, Zr, Hf, V+, Nb+, Ta+). [...] Read more.
We performed quantum chemical calculations on the geometries, electronic structures, bonding properties, and stability strategy of endohedral metallofullerenes TM@C28 (TM = Sc, Y, La, Ti, Zr, Hf, V+, Nb+, Ta+). Our calculations revealed that there are three different lowest-energy structures with C2v, C3v, and Td symmetries for TM@C28. The HOMO–LUMO gap of all these structures ranges from 1.35 eV to 2.31 eV, in which [V@C28]+ has the lowest HOMO–LUMO gap of 1.35 eV. The molecular orbitals are mainly composed of fullerene cage orbitals and slightly encapsulated metal orbitals. The bonding analysis on the metal–cage interactions reveals they are dominated by the Coulomb term ΔEelstat and the orbital interaction term ΔEorb, in which the orbital interaction term ΔEorb contributes more than the Coulomb term ΔEelstat. The addition of one or two CF3 groups to [V@C28]+ could increase the HOMO–LUMO gap and further increase the stability of [V@C28]+. Full article
(This article belongs to the Special Issue Research on Metallofullerenes)
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13 pages, 2284 KiB  
Article
Theoretical Insights into the Regiodivergence in Ni-Catalyzed [2+2+2] Cycloaddition of Unsymmetric Diynes and CO2
by Kun Zhang, Qiwen Huang, Cun Yang and Xinyao Li
Inorganics 2024, 12(2), 39; https://doi.org/10.3390/inorganics12020039 - 25 Jan 2024
Viewed by 1066
Abstract
To achieve the peak of carbon dioxide emission and carbon neutrality, utilizing it as a renewable carbon unit in organic synthesis presents an effective chemical solution for sustainable development. In this study, we report a theoretical investigation into the reaction mechanism and the [...] Read more.
To achieve the peak of carbon dioxide emission and carbon neutrality, utilizing it as a renewable carbon unit in organic synthesis presents an effective chemical solution for sustainable development. In this study, we report a theoretical investigation into the reaction mechanism and the regiodivergence of the Ni-catalyzed [2+2+2] cycloaddition of unsymmetric diynes and CO2 by using DFT calculations. The reaction mechanisms can be classified into two types: one is related to the oxidative coupling of the C≡C moiety with CO2, and the other is related to the oxidative coupling of the two C≡C moieties of diyne. In each type, two possible paths were proposed depending upon the positions of the substituents (H and silyl). Our calculation results indicate that the oxidative coupling of the C≡C moiety and CO2 favors the positions of H-substituent, while the oxidative coupling of the two C≡C moieties is beneficial for inserting CO2 at the positions of silyl-substituent. The regiodivergence is controlled by substrate chain-length and ligand in the different reaction mechanisms. Full article
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20 pages, 2978 KiB  
Review
Process Parameter Optimisation for Endohedral Metallofullerene Synthesis via the Arc-Discharge Method
by Sapna Sinha, Karifa Sanfo, Panagiotis Dallas, Sujay Kumar and Kyriakos Porfyrakis
Inorganics 2024, 12(2), 38; https://doi.org/10.3390/inorganics12020038 - 25 Jan 2024
Viewed by 1226
Abstract
Fullerenes have a unique structure, capable of both encapsulating other molecules and reacting with those on the exterior surface. Fullerene derivatives have also been found to have enormous potential to address the challenges of the renewable energy sector and current environmental issues, such [...] Read more.
Fullerenes have a unique structure, capable of both encapsulating other molecules and reacting with those on the exterior surface. Fullerene derivatives have also been found to have enormous potential to address the challenges of the renewable energy sector and current environmental issues, such as in the production of n-type materials in bulk heterojunction solar cells, as antimicrobial agents, in photocatalytic water treatment processes, and in sensor technologies. Endohedral metallofullerenes, in particular, can possess unpaired electron spins, driven by the enclosed metal atom or cluster, which yield valuable magnetic properties. These properties have significant potential for applications in molecular magnets, spin probes, quantum computing, and devices such as quantum information processing,, atomic clocks, and molecular magnets. However, the intrinsically low yield of endohedral fullerenes remains a huge obstacle, impeding not only their industrial utilization but also the synthesis and characterization essential for exploring novel applications. The low yield and difficulty in separation of different types of endohedral fullerenes results in the usage of a large amount of solvents and energy, which is detrimental to the environment. In this paper, we analyse the methodologies proposed by various researchers and identify the critical synthesis parameters that play a role in increasing the yields of fullerenes. Full article
(This article belongs to the Special Issue Research on Metallofullerenes)
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14 pages, 6264 KiB  
Article
Facile Synthesis of Hollow V2O5 Microspheres for Lithium-Ion Batteries with Improved Performance
by Hailong Fei, Peng Wu, Liqing He and Haiwen Li
Inorganics 2024, 12(2), 37; https://doi.org/10.3390/inorganics12020037 - 24 Jan 2024
Viewed by 1145
Abstract
Micro-nanostructured electrode materials are characterized by excellent performance in various secondary batteries. In this study, a facile and green hydrothermal method was developed to prepare amorphous vanadium-based microspheres on a large scale. Hollow V2O5 microspheres were achieved, with controllable size, [...] Read more.
Micro-nanostructured electrode materials are characterized by excellent performance in various secondary batteries. In this study, a facile and green hydrothermal method was developed to prepare amorphous vanadium-based microspheres on a large scale. Hollow V2O5 microspheres were achieved, with controllable size, after the calcination of amorphous vanadium-based microspheres and were used as cathode materials for lithium-ion batteries. As the quantity of V2O5 microspheres increased, the electrode performance improved, which was ascribed to the smaller charge transfer impedance. The discharge capacity of hollow V2O5 microspheres could be up to 196.4 mAhg−1 at a current density of 50 mAg−1 between 2.0 and 3.5 V voltage limits. This sheds light on the synthesis and application of spherical electrode materials for energy storage. Full article
(This article belongs to the Special Issue Novel Materials in Li–Ion Batteries)
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13 pages, 6502 KiB  
Article
Green Synthesis of Gold and Copper Nanoparticles by Lannea discolor: Characterization and Antibacterial Activity
by Unarine Rambau, Nndivhaleni Anox Masevhe and Amidou Samie
Inorganics 2024, 12(2), 36; https://doi.org/10.3390/inorganics12020036 - 24 Jan 2024
Viewed by 1446
Abstract
Green synthesis using plant extracts has emerged as an eco-friendly, clean, and viable alternative to chemical and physical approaches. Herein, the leaf, stem, and root extracts of Lannea discolor were utilized as a reducing and stabilizing agent in synthesizing gold (AuNPs) and copper [...] Read more.
Green synthesis using plant extracts has emerged as an eco-friendly, clean, and viable alternative to chemical and physical approaches. Herein, the leaf, stem, and root extracts of Lannea discolor were utilized as a reducing and stabilizing agent in synthesizing gold (AuNPs) and copper (CuNPs) nanoparticles. The formation of AuNPs and CuNPs, confirmed by their color change, was characterized by UV-Vis spectroscopy (UV-Vis), scanning electron microscopy analysis, and energy-dispersive X-ray (SEM-EDX), transmission electron microscopy (TEM), and Fourier-transform infrared spectroscopy (FTIR), coupled with minimum inhibitory concentration (MIC) antibacterial assays. Gold nanoflowers (AuNFs), NPs, and CuNPs peaked at wavelengths of 316, 544, and 564 nm, respectively. TEM showed unexpected nanoflowers (30–97 nm) in the leaf extracts and spherical NPs (10–33 nm; 9.3–37.5) from stem and root extracts, while spherical CuNPs (20–104 nm) were observed from all the extracts. EDX confirmed the presence of metal salts, and FTIR revealed stable capping agents. AuNPs and NFs from L. discolor extracts showed appreciable antibacterial activity against Staphylococcus aureus (ATCC 25923), Escherichia coli (ATCC 25922), Pseudomonas aeruginosa (ATCC 27853), Klebsiella pneumoniae (ATCC 700603), and Bacillus subtilis (ATCC 6633) when compared to the plant extracts. At the same time, none was observed from the CuNPs. These AuNPs and CuNPs are particularly appealing in various biomedical and conductivity manufacturing applications due to their shapes and sizes and economical and environmentally friendly production. To our knowledge, this is the first study of the synthesis of gold and copper nanoparticles from L. discolor. Full article
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