Potential impact of mesenchymal stem cells on nephrotoxicity induced by gamma irradiation and antiepileptic drugs cotherapy in rats

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Abstract

The goal of this study was to assess the influence of bone marrow-derived mesenchymal stem cells (BM-MSCs) on the nephrotoxicity induced by fractionated doses of gamma irradiation (Rad) and the cotherapy of levetiracetam and oxcarbazepine in male rats. Adult rats were randomly divided into four groups. Group I: Control, Group II: antiepileptic drugs (AEDs), Group III: AEDs +Rad and Group IV: AEDs + Rad + MSCs. Rats treated with AEDs and exposed to fractionated doses of γ-irradiation displayed a discernible increase in serum urea, creatinine, kidney injury marker, kidney malondialdehyde, transforming growth factor beta (TGF-β) and the relative expression of Smad3 along with a decrease in the relative expression of Smad7 and glutathione level. Alternatively, groups treated with BM-MSCs with AEDs and Rad showed a substantial modification in the majority of the evaluated parameters and looked to be successful in reducing the hazards of the combination therapy of AEDs and radiation. The reno-histopathological study supports the biochemical analysis. In conclusion, BM-MSCs exhibited therapeutic potential against nephrotoxicity induced by fractionated doses of γ-irradiation and AEDs. The outcome was brought about by the downregulation of the TGF-β/Smad pathway. BM-MSCs might be suggested as a valuable therapeutic strategy to overcome kidney injury induced by gamma irradiation during AEDs cotherapy.

Recent Advances in Borylation via Electron Donor–Acceptor Complex Photoactivation

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Recent Advances in Borylation via Electron Donor–Acceptor Complex Photoactivation

Recent advances in photoinduced borylation reactions employing an electron donor–acceptor complex photoactivation strategy are reviewed. The milestones achieved in the area as well as the existing limitations are highlighted. Additionally, possible future developments that could further advance this field are discussed.


Abstract

Photoinduced borylation is becoming a fascinating and growing research field in synthetic chemistry. On the other hand, electron donor–acceptor (EDA) complex photoactivation has emerged as an alternative strategy to generate active open-shell species without the need for photosensitizers. Suitable organoboron compounds can serve as the electron donor or acceptor to form the corresponding electron donor–acceptor complexes, which then undergo photoinduced intracomplex single electron transfer (SET) to generate carbon- or boron-centered radicals for the construction of new C−B bonds. In this Concept paper, we review recent advances in photoinduced borylation via the EDA complex photoactivation strategy surveying the relevant literature until December 2022.

Synthesis, Structure, and Catalytic Activity of Cyclometalated Iridium Complexes with a Bidentate POC Ligand

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Synthesis, Structure, and Catalytic Activity of Cyclometalated Iridium Complexes with a Bidentate POC Ligand

Synthesis and characterization of cyclometalated iridium complexes (POC)(L)IrHCl with a bidentate POC ligand is presented. The catalytic activity of complexes (POC)(L)IrHCl in acceptorless dehydrogenation of 1-phenylethanol and transfer dehydrogenation of ethanol is discussed and compared to (POCOP)IrHCl and (PCN)IrHCl pincer complexes.


Abstract

Synthesis, characterization and catalytic activity of cyclometalated iridium complexes with a bidentate POC ligand is presented. Metalation of POC-H (di-tert-butyl(phenoxy)phosphane) with [Ir(COD)Cl]2 proceeded rapidly at room temperature and afforded mixture of (POC)(POC-H)IrHCl (1 a) and (POC)(COD)IrHCl (1 b), from which complexes (POC)(L)IrHCl where L=PPh3 (1 c), bipyridine (1 d) and [2,2′-bipyridine]-6,6′-diol (1 e) were prepared through ligand exchange. The compounds were tested in acceptorless dehydrogenation of 1-phenylethanol and transfer dehydrogenation of ethanol in a context of comparison with pincer counterparts (POCOP)IrHCl and (PCN)IrHCl. An attempt to prepare a dihydride complex from 1 e led to dimeric complex [(POC)(bipy-diol−)IrH]2 (3) that could explain the low activity of 1 e. DFT studies provided insight into POC-H vs POCOP-H metalation mechanism.

Stoichiometric Control of Guest Recognition of Self‐Assembled Palladium(II)‐Based Supramolecular Architectures

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Stoichiometric Control of Guest Recognition of Self-Assembled Palladium(II)-Based Supramolecular Architectures

Stoichiometry can be used in a flexible system to switch between a 2+2 [Pd2(L)2]4+ macrocycle and a [Pd(L)2]2+ compound where the uncomplexed arms occlude access to the cationic part of the molecule by guests. We can thereby controllably regulate affinity between our host and an aromatic guest.


Abstract

We report flexible [Pd(L)2]2+ complexes where there is self-recognition, driven by π-π interactions between electron-rich aromatic arms and the cationic regions they are tethered to. This self-recognition hampers the association of these molecules with aromatic molecular targets in solution. In one case, this complex can be reversibly converted to an ‘open’ [Pd2(L)2]4+ macrocycle through introduction of more metal ion. This is accomplished by the ligand having two bidentate binding sites: a 2-pyridyl-1,2,3-triazole site, and a bis-1,2,3-triazole site. Due to favourable hydrogen bonding, the 2-pyridyl-1,2,3-triazole units reliably coordinate in the [Pd(L)2]2+ complex to control speciation: a second equivalent of Pd(II) is required to enforce coordination to bis-triazole sites and form the macrocycle. The macrocycle interacts with a molecular substrate with higher affinity. In this fashion we are able to use stoichiometry to reversibly switch between two different species and regulate guest binding.

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.