Monthly Archives: September 2023

Get under the Umbrella: A Comprehensive Gateway for Researchers on Lanthanide‐Based Single‐Molecule Magnets

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Get under the Umbrella: A Comprehensive Gateway for Researchers on Lanthanide-Based Single-Molecule Magnets

In order to help young researchers in Molecular Magnetism, this article proposes a “review of reviews” also known as an “umbrella review” on lanthanide-based monomolecular magnets (4 f-SMM). Bibliographic search techniques are commented together with AI-based tools for bibliographic search, indexing, and summarization. Milestones in 4 f-SMM are identified. Books, book articles, and reviews are contextualized. This article is therefore proposed as a gateway to the 4 f-SMM field.


Abstract

The number of scientific articles that need to be considered to cover a research topic is ever-increasing and quite difficult for a newcomer to assimilate. This is particularly true in dynamic discipline like Molecular Magnetism. In order to help young researchers in this field, this article proposes a “review of reviews” also known as an “umbrella review” on lanthanide-based single-molecule magnets (4 f-SMM). As a preamble, various bibliographic search techniques and AI-based tools for bibliographic search, indexing, and summarization are proposed and commented. Then, the main milestones in 4 f-SMM are identified. In the core of the paper, books, book articles, and reviews dealing with 4 f-SMM are contextualized and classified by subtopics. This article is therefore proposed as a gateway to the 4 f-SMM field.

A Dinuclear Re Complex as a Multi Talent – Photocatalysis and Electrocatalysis combined with Spectroscopy

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A Dinuclear Re Complex as a Multi Talent – Photocatalysis and Electrocatalysis combined with Spectroscopy

The synthesis and characterization of two isomers of a homobimetallic rhenium complex is reported. The photo- as well as electrocatalytic activity in the CO2 to CO transformation was determined and discussed in comparison to the monometallic analogue and bimetallic conformational isomers. Further spectroscopic investigations led to the proposition of a new reaction mechanism involving cooperative CO2 activation.


Abstract

Mononuclear rhenium complexes have been widely studied as photo- and electrocatalysts. However, dinuclear systems with cooperative properties have rarely been investigated. On the basis of two homobimetallic rhenium complexes, we report the synthesis and characterization of two isomers and their photo- and electrochemical properties. By combining the respective isomer with the photosensitizer [Ir(dFppy)3] (Ir, dFppy=2-(4,6-difluorophenyl) pyridine)) enhanced CO2 to CO transformation could be observed and by further spectroscopic investigations the reaction mechanism could be fathomed. The observed enhanced catalytic activity compared to monometallic systems derives from the cooperative Re−Re interaction through two electron reduction on the complex (and thereby formation of an intermediate species with a Re−Re bond). Using LSV measurements the cooperative CO2 activation was also observed for one of the isomers, cisL1-Re2Cl2 , in electrocatalytic measurements. The two isomers have a somewhat lower catalytic activity than earlier prepared geometric isomers, but show better catalytic properties than their mononuclear counterpart.

Calix[8]arene‐Based Manganese Complexes for Electrocatalytic CO2 Reduction

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Calix[8]arene-Based Manganese Complexes for Electrocatalytic CO2 Reduction


Abstract

Transition metal catalysts with modified second-coordination sphere employed in the electrocatalytic CO2 can result in increased activity or directed product selectivity. Calixarenes can form metal complexes and potentially catalyze reactions within its cavity, taking advantage of the surrounding phenols groups to tune the reactivity by second-coordination sphere effects. Here, we present a Mn(I) bromotricarbonyl complex with phenanthroline-functionalized calix[8]arene ligands capable of electrocatalytically reducing CO2 into different products with 2,2,2-trifluoroethanol as proton donor. The selectivity of the reaction seems to be affected by the calixarene cavity: two calixarene-free analogous complexes reduce CO2 to CO almost exclusively, while the calixarene complexes produce primarily CO, H2. Interestingly, in some cases the less frequently observed CH4 was also detected, albeit with low Faradaic efficiency. Thus, the manganese center placed within the calixarene cavity promotes the formation of reduced CO2 products by more than two electrons and two protons, affording CH4 in some cases.

Tumor Carbohydrate Associated Antigen Analogs as Potential Binders for Siglec‐7

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Tumor Carbohydrate Associated Antigen Analogs as Potential Binders for Siglec-7

The binding recognition of two structurally constrained sialyl derivatives by Siglec-7was investigated. The flexibility of Siglec-7 loops allowed the preferred accommodation of the more rigid compound containing a biphenyl moiety. Our results set the basis for the design and development of novel compounds as potential modulators for Siglec-7.


Abstract

We investigated two recently synthesized and characterized sialyl derivatives, bearing the Neu5Ac-α-(2-6)-Gal epitope, as promising binders for Siglec-7, an inhibitory Siglec mainly found on natural killer cells. A variety of sialoglycan structures can be recognized by Siglec-7 with implications in the modulation of immune responses. Notably, overexpression of sialylated glycans recognized by Siglec-7 can be associated with the progression of several tumors, including melanoma and renal cell carcinoma. NOE-based NMR techniques, including Saturation Transfer Difference and transferred-NOESY NMR, together with molecular docking and dynamic simulations were combined to shed light on the molecular basis of Siglec-7 recognition of two conformationally constrained Sialyl-Tn antigen analogs. We, therefore, identify the ligands epitope mapping and their conformational features and propose 3D models accurately describing the protein-ligand complexes. We found that the binding site of Siglec-7 can accommodate both synthetic analogs, with the sialic acid mainly involved in the interaction. Moreover, the flexibility of Siglec-7 loops allows a preferred accommodation of the more rigid compound bearing a biphenyl moiety at position 9 of the sialic acid that contributed to the interaction to a large extent. Our findings provided insights for developing potential novel high affinity ligands for Siglec-7 to hinder tumor evasion.

Trapping an Unexpected/Unprecedented Hexanuclear Ce(III) Hydrolysis Product with Neutral 4‐Amino‐1,2,4‐triazole

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Trapping an Unexpected/Unprecedented Hexanuclear Ce(III) Hydrolysis Product with Neutral 4-Amino-1,2,4-triazole

We describe a straightforward pathway to obtain lanthanide hydroxo polynuclear clusters from lanthanide salt hydrates and a combination of azoles. 4-NH2-1,2,4-triazole was found to play an important role both as a reaction medium and the structure-forming agent leading to multiple clusters with various nuclearity including the first example of a high nuclearity lanthanide complex where all Ln atoms are pairwise connected through 12 N-donor ligands.


Abstract

Using Ce(III) as both a representative lanthanide and actinide analog, the ability of mixtures of acidic and basic azoles to allow direct access to homoleptic N-donor f-element complexes in one pot reactions from hydrated salts as starting materials was examined by reacting mixtures of 4-amino-1,2,4-triazole (4-NH2-1,2,4-Triaz), 5-amino-tetrazole (5-NH2-HTetaz), and 1,2,3-triazole (1,2,3-HTriaz) in 1 : 1 and 1 : 3 ratios with CeCl3 ⋅ 7H2O, [C2mim]3[CeCl6] ([C2mim]+=1-ethyl-2-methylimidazolium), and Ce(NO3)3 ⋅ 6H2O. Although unsuccessful in our goal, structural analysis revealed that neutral 4-NH2-1,2,4-Triaz is structure directing via η 2 μ 2 κ 2 bridging, with the formation of the dinuclear complexes [Ce2Cl2(μ2-4-NH2-1,2,4-Triaz)4(H2O)8]Cl4 ⋅ 4H2O, [Ce2(μ2-4-NH2-1,2,4-Triaz)4(4-NH2-1,2,4-Triaz)2(Cl)6], and [4-NH2-1,2,4-HTriaz][Ce2(μ2-4-NH2-1,2,4-Triaz)2(μ2-NO3)(NO3)6(H2O)2]. When the synthetic conditions favored hydrolysis, the hexanuclear Ce(III) complex [Ce6(μ3-O)4(μ3-OH)2(μ3-Cl)2(Cl)6(μ2-4-NH2-1,2,4-Triaz)12] ⋅ 7H2O was isolated. This unexpected hydrolysis product represents the first example of a high nuclearity lanthanide complex where all Ln atoms are pairwise connected through 12 N-donor ligands or 12 neutral bridging ligands of any type, a rare example of incorporation of non-oxo coordinating anions in the M6X8 core, and the first reported Ce(III) hexanuclear complex of this type.

Temperature‐Dependent Structures of Single‐Atom Catalysts

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Temperature-Dependent Structures of Single-Atom Catalysts

The local structures of Ni single-atom catalysts were regulated by adjusting carbonization temperature of their precursors. The oxidation state, total coordination number, and bond length of the metal center decrease with the increase of the carbonization temperature. The relationship between structure and performance was explored. The structure after regulation could promote the adsorption of CO2 and improve electrocatalytic CO2 reduction activity.


Abstract

Single-atom catalysts (SACs) have the unique coordination environment and electronic structure due to the quantum size effect, which plays an essential role in facilitating catalytic reactions. However, due to the limited understanding of the formation mechanism of single atoms, achieving the modulation of the local atomic structure of SACs is still difficult and challenging. Herein, we have prepared a series of Ni SACs loaded on nitrogen-doped carbon substrates with different parameters using a dissolution-and-carbonization method to systematically investigate the effect of temperature on the structure of the SACs. The results of characterization and electrochemical measurements are analyzed to reveal the uniform law between temperature and the metal loading, bond length, coordination number, valence state and CO2 reduction performance, showing the feasibility of controlling the structure of SACs through temperature to regulate the catalytic performance. This is important for the understanding of catalytic reaction mechanisms and the design of efficient catalysts.

Exploring LiZnNbO4 as a Host for New Colored Compounds: Synthesis, Structure, and Material Properties of NbZn1‐x Mx LiO4 (M=Mn, Co, Ni, Fe) and Nb1‐ySby Zn1‐x Mx LiO4 (M=Co, Ni)

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Exploring LiZnNbO4 as a Host for New Colored Compounds: Synthesis, Structure, and Material Properties of NbZn1-x Mx LiO4 (M=Mn, Co, Ni, Fe) and Nb1-ySby Zn1-x Mx LiO4 (M=Co, Ni)

Transition elements (Co2+, Ni2+, and Cu2+ ions) were substituted in place of tetrahedral Zn2+ ions in the tetragonal non-centrosymmetric spinel LiZnNbO4 (LZN) and LiZnNb0.5Sb0.5O4 (LZSN) compounds to form new colored compounds. The dielectric studies indicated reasonable values with low loss. The compounds were SHG-active. Magnetic studies reveal the Co2+ substituted Li(Zn0.25Co0.75)NbO4 compound to be antiferromagnetic in nature.


Abstract

The non - centrosymmetric tetragonal inverse spinel structure of LiZnNbO4 has been explored with a view to prepare new colored compounds. The substitution of Co2+, Ni2+, Fe2+, Mn2+, and Cu2+ ions were attempted in the place of Zn2+ ions and Sb5+ ions in place of Nb5+ ions. The studies indicated that 0.75 Zn2+ ions in LiZnNbO4 can be replaced by Co2+ ions and 0.5 Zn2+ ions in LiZnNb0.5Sb0.5O4 compound. The substitution of Co2+ ions gives rise to different shades of blue color in Li(Zn1-xCox)NbO4 compounds and from ink blue to blue-green color in Li(Zn1-xCox)(Nb0.5Sb0.5)O4 compounds. The different colors observed in the present study were explained by the traditional allowed d-d transitions as well as the metal-to-metal charge transfer (MMCT) transitions involving Nb5+ (4d 0) ions and partially filled 3d electrons. The SHG studies indicate that the prepared compounds are SHG active. All the compounds exhibit reasonable dielectric behavior with low loss. The XPS studies confirm the oxidation states of the different substituted ions. Raman studies indicate variations in the bands due to the substitutions in the parent LiZnNbO4 phase. Magnetic studies on the Co2+ ions substituted compounds suggest antiferromagnetic behavior.

Optimizing Renewable Ammonia Production for a Sustainable Fertilizer Supply Chain Transition

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Optimizing Renewable Ammonia Production for a Sustainable Fertilizer Supply Chain Transition

Ammonia produced locally from renewable energy and water electrolysis can be economically competitive with the existing fossil-based global market if its production systems are designed and deployed optimally over the next decade. This transition would reduce the carbon intensity of nitrogen fertilizer by 99 % while ensuring stable and predictable fertilizer prices for the farmers who use this indispensable commodity.


Abstract

Local renewable ammonia production using electrolytic hydrogen is an emerging approach to alleviate emissions attributed to synthetic nitrogen fertilizer production while also insulating against fluctuations in fertilizer prices and mitigating transportation costs and emissions. However, replacing ammonia currently produced using fossil fuels will not be immediate. To this end, we develop a supply chain transition model, which first optimizes the design and hourly operation of new renewable ammonia facilities to minimize production costs and then optimizes the annual installation timing, production scale, and location of these new renewable facilities along with ammonia transportation to meet county resolution demands. The objective is to augment and eventually replace conventional ammonia market imports in an economically competitive manner. We performed a case study for Minnesota's ammonia supply chain and found that a full transition to in-state renewable production by 2032 is optimal. This is incentivized by the U.S. federal government's clean hydrogen production credits. This transition results in 99 % reduction in carbon intensity along with stable supply costs below $475 per metric tonne. New renewable production facilities are an order of magnitude smaller than existing conventional plants. They use both wind and solar resources and operate dynamically to minimize expensive battery and hydrogen storage capacities.

Nutraceutical Activity of Anthocyanins from the Edible Berries of Rhamnus pompana

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Nutraceutical Activity of Anthocyanins from the Edible Berries of Rhamnus pompana


Abstract

We present the inhibitory properties of the R. pompana anthocyanin fraction (RPAF) and its major constituents on alpha-glucosidase (AG), pancreatic lipase (PL), HMG-CoA reductase, and ornithine decarboxylase (ODC). The effect of RPAF was also evaluated in ICR male mice subjected to oral glucose tolerance test (OGTT) and hypercaloric/atherogenic diet for 30 days. RP-HPLC/MS profiling revealed that RPAF contained five major anthocyanins and induced slight inhibition on PL and HMG-CoA reductase (IC50, 245–338 μg mL−1) whereas strong activity on AG and ODC (IC50, 130–133 μg mL−1) was observed. Kinetic studies and molecular docking with pelargonidin-3-O-rutinoside (P3R) on ODC, revealed changes in Km (0.9514–0.9746 mM) and Vmax (1.96–2.32 μmol mg−1 min−1) suggesting mixed inhibition and molecular interaction with two active sites of ODC. P3R showed antiproliferative activity (IC50, 46.5 μM) and decreased polyamine accumulation in DLD-1 cells. The results of OGTT confirmed that RPAF regulates postprandial glucose levels in diabetic animals which experienced a significant glucose depletion (30 %; p<0.001) from 30 to 120 min post-treatment. Prolonged supplementation of RPAF caused significant decrease (p<0.001) in plasma glucose, total cholesterol, LDL-c and triglycerides as well as significant increase (p<0.001) of HDL-c compared with normoglycemic untreated animals.

Design, Synthesis, Anticancer Evaluation and Molecular Modeling Studies of New Thiazolidinone‐Benzoate Scaffold as EGFR Inhibitors, Cell Cycle Interruption and Apoptosis Inducers in HepG2

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Design, Synthesis, Anticancer Evaluation and Molecular Modeling Studies of New Thiazolidinone-Benzoate Scaffold as EGFR Inhibitors, Cell Cycle Interruption and Apoptosis Inducers in HepG2


Abstract

Synthesis of new anticancer candidates with protein kinases inhibitory potency is a major goal of pharmaceutical science and synthetic research. This current work represents the synthesis of a series of substituted benzoate-thiazolidinones. Most prepared thiazolidinones were evaluated in vitro for their potential anticancer activity against three cell lines by MTT assay, and they found to be more effective against cancer cell lines with no harm toward normal cells. Thiazolidinones 5 c and 5 h were further evaluated to be kinase inhibitors against EGFR showing effective inhibitory impact (with IC50 value; 0.2±0.009 and 0.098±0.004 μM, for 5 c and 5 h, respectively). Furthermore, 5 c and 5 h have effects on cell cycle and apoptosis induction capability in HepG2 cell lines by DNA-flow cytometry analysis and annexin V-FITC apoptosis assay, respectively. The results showed that they have effect of disrupting the cell cycle and causing cell mortality by apoptosis in the treated cells. Moreover, molecular docking studies showed better binding patterns for 5 c and 5 h with the active site of the epidermal growth factor receptor (EGFR) protein kinase (PDB code 1M17). Finally, toxicity risk and physicochemical characterization by Osiris method was performed on most of the compounds, revealing excellent properties as possible drugs.