Cobalt based nanostructured alloys: Versatile high performance robust hydrogen evolution reaction electro-catalysts for electrolytic and photo-electrochemical water splitting

Engineering reduced noble metal containing electro-catalysts exhibiting superior electrochemical performance is important for efficient and economic production of hydrogen from electrolytic and photoelectrochemical (PEC) water splitting reactions. In this study, nanostructured Co–Ir solid solution alloys, Co_1?x(Ir_x) (x = 0.2, 0.3, 0.4) have been studied as electro-catalysts for hydrogen evolution reaction (HER). Co_1?x(Ir_x) (x = 0.3, 0.4) exhibit similar onset over-potential to Pt/C and lower over-potential required for Co_1?x(Ir_x) (x = 0.3, 0.4) than Pt/C in acidic, neutral as well as basic media, suggesting excellent electrochemical activity of Co–Ir alloys, further studied using theoretical first principles density functional theory calculations. Co_1?x(Ir_x) exhibit excellent electrochemical stability in acidic media similar to that of Pt/C. The applied bias photon-to-current efficiency obtained using Co_1?x(Ir_x) (x = 0.3, 0.4) electro-catalysts and (Sn_0.95Nb_0.05)O₂:N-600 NTs as photoanode in H-type cell is ～5.74% and ～7.92%, respectively which is ～40% and ～93% higher than Pt/C (～4.1%) indicating considerable promise of the system.     

Molecular and Electronic Structures of Neutral Polynitrogens: Review on the Theory and Experiment in 21st Century

The data on the existence and physicochemical characteristics of uncharged single element chemical compounds formed by nitrogen atoms and containing more than two nuclides of this element (from N₄ to N₁₂₀, oligomeric and polymeric polynitrogens) have been systematized and generalized. It has been noticed that these data have a predominantly predictive character and were obtained mainly using quantum chemical calculations of various levels (HF, DFT, MP, CCSD etc.). The possibility of the practical application of these single element compounds has been considered. The review mainly covers articles published in the last 25 years. The bibliography contains 128 references.     

High-temperature strength behavior of tantalum diboride to 2000°C

This study investigated the high-temperature strength of spark plasma sintered tantalum diboride (TaB₂) for the first time. TaB₂ exhibited a unique elastic fracture behavior below 1900°C, unlike other transition metal diborides. The consolidation process involved spark plasma sintering at 2000–2200°C yielding dense TaB₂ samples. The flexural strength was measured at elevated temperatures up to 2000°C, showing a quite high flexural strength of 400 ± 20 MPa at 1900°C. These findings provide valuable insights into the high-temperature behavior of TaB₂, highlighting its potential for advanced applications.     

Pushing the Boundaries of Structural Heterogeneity with the Lipid A of Marine Bacteria Cellulophaga

Marine bacteria, which are often described as chemical gold, are considered an exceptional source of new therapeutics. Considerable research interest has been given to lipopolysaccharides (LPSs), the main components of the Gram-negative outer membrane. LPS and its lipid A portion from marine bacteria are known to exhibit a tricky chemistry that has been often associated with intriguing properties such as behaving as immune adjuvants or anti-sepsis molecules. In this scenario, we report the structural determination of the lipid A from three marine bacteria within the Cellulophaga genus, which showed to produce an extremely heterogenous blend of tetra- to hexa-acylated lipid A species, mostly carrying one phosphate and one D-mannose on the glucosamine disaccharide backbone. The ability of the three LPSs in activating TLR4 signaling revealed a weaker immunopotential by C. baltica NNO 15840^T and C. tyrosinoxydans EM41^T, while C. algicola ACAM 630^T behaved as a more potent TLR4 activator.     

Promising Antifungal and Antibacterial Agents Based on 5-Aryl-2,2′-bipyridines and Their Heteroligand Salicylate Metal Complexes: Synthesis,Bioevaluation, Molecular Docking

A series of new 5-aryl-2,2′-bipyridines and their (polyfluoro)salicylate complexes of Cu(II), Co(II) and Mn(II) were synthesized. Their antimicrobial activity was evaluated in vitro against six strains of Trichophytons, E. floccosum, M. canis, C. ablicans and Gram-negative bacteria N. gonorrhoeae. Among azo-ligands, Ph-bipy and Tol-bipy showed promising antifungal activity (minimum inhibitory concentration (MIC)<0.8–27 μM). Their antifungal action was found can be realized via binding Fe(III) ions. Tol-bipy suppressed growth of Gram-positive bacteria S. aureus, S. aureus MRSA and their monospecies biofilms (MIC 6–16 μM). Using molecular docking, the anti-staphylococcal action mechanism based on the inhibition of S. aureus DNA gyrase GyrB was proposed for the lead compounds. Among metal complexes, Cu(II) and Mn(II) complexes based on tetrafluorosalicylic acid and Tol-bipy or Ph-bipy had the high antifungal activity (MIC<0.24–32 μM). Mn(SalF₄−2H)₂(Tol-bipy)₂] suppressed the growth of seven Candida strains at MIC 12–24 μM. [Cu(Sal−2H)(Ph-bipy)] and [Cu(SalF₃−2H)(Ph-bipy)₂] showed the promising anti-gonorrhoeae activity (MIC 4.2–5.2 μM). (Cu(SalF_n−2H)(Tol-bipy)₂], [Cu(SalF₄−2H)(Ph-bipy)₂] and [Cu(SalF₃−2H)(Ph-bipy)₂]) were found active against the bacteria of S. aureus, S. aureus MRSA and their biofilms (MIC 2.4–41.4 μM). The most active compounds were tested for toxicity in vitro against human embryonic kidney (HEK-293) cells and in vivo experiments with CD-1 mice.     

Mithplatins: Mithramycin SA-Pt(II) Complex Conjugates for the Treatment of Platinum-Resistant Ovarian Cancers

DNA coordinating platinum (Pt) containing compounds cisplatin and carboplatin have been used for the treatment of ovarian cancer therapy for four decades. However, recurrent Pt-resistant cancers are a major cause of mortality. To combat Pt-resistant ovarian cancers, we designed and synthesized a conjugate of an anticancer drug mithramycin with a reactive Pt(II) bearing moiety, which we termed mithplatin. The conjugates displayed both the Mg²⁺-dependent noncovalent DNA binding characteristic of mithramycin and the covalent crosslinking to DNA of the Pt. The conjugate was three times as potent as cisplatin against ovarian cancer cells. The DNA lesions caused by the conjugate led to the generation of DNA double-strand breaks, as also observed with cisplatin. Nevertheless, the conjugate was highly active against both Pt-sensitive and Pt-resistant ovarian cancer cells. This study paves the way to developing mithplatins to combat Pt-resistant ovarian cancers.     

Proximity Coupling of Graphene to a Submonolayer 2D Magnet

Imprinting magnetism into graphene may lead to unconventional electron states and enable the design of spin logic devices with low power consumption. The ongoing active development of 2D magnets suggests their coupling with graphene to induce spin-dependent properties via proximity effects. In particular, the recent discovery of submonolayer 2D magnets on surfaces of industrial semiconductors provides an opportunity to magnetize graphene coupled with silicon. Here, synthesis and characterization of large-area graphene/Eu/Si(001) heterostructures combining graphene with a submonolayer magnetic superstructure of Eu on silicon are reported. Eu intercalation at the interface of the graphene/Si(001) system results in a Eu superstructure different from those formed on pristine Si in terms of symmetry. The resulting system graphene/Eu/Si(001) exhibits 2D magnetism with the transition temperature controlled by low magnetic fields. Negative magnetoresistance and the anomalous Hall effect in the graphene layer provide evidence for spin polarization of the carriers. Most importantly, the graphene/Eu/Si system seeds a class of graphene heterostructures based on submonolayer magnets aiming at applications in graphene spintronics.     

Hydroxylherderite (Ca2Be2P2O8(OH)2) stability under extreme conditions (up to 750°C/100 GPa)

Hydroxylherderite, Ca₂Be₂P₂O₈(OH)₂, is among the most common beryllophosphates in nature and could play a substantial role in Be geochemical cycle. Hydroxylherderite P–T stability and crystal structure behavior were studied under extreme conditions (up to 750°C/100 GPa) using in situ single-crystal and powder X-ray diffraction and Raman spectroscopy. The mineral demonstrated high stability under high-pressure conditions (up to ∼100 GPa) without any phase transitions. Under high-temperature conditions, it was stable up to about 700°C, when it decomposed with the formation of fluorapatite Ca₅(PO₄)₃F and hurlbutite CaBe₂P₂O₈. The beryllophosphate member of the gadolinite supergroup is the most stable mineral (material) under high-pressure conditions, compared to aluminum-, boro- and beryllosilicates.     

Molecular Architecture Effects on Bulk Nanostructure in Bis(Orthoborate) Ionic Liquids

A series of 19 ionic liquids (ILs) based on phosphonium and imidazolium cations of varying alkyl-chain lengths with the orthoborate anions bis(oxalato)borate [BOB]⁻, bis(mandelato)borate, [BMB]⁻ and bis(salicylato)borate, [BScB]⁻, are synthesized and studied using small-angle neutron scattering (SANS). All measured systems display nanostructuring, with 1-methyl-3-n-alkyl imidazolium-orthoborates forming clearly bicontinuous L₃ spongelike phases when the alkyl chains are longer than C₆ (hexyl). L₃ phases are fitted using the Teubner and Strey model, and diffusely-nanostructured systems are primarily fitted using the Ornstein-Zernicke correlation length model. Strongly-nanostructured systems have a strong dependence on the cation, with molecular architecture variation explored to determine the driving forces for self-assembly. The ability to form well-defined complex phases is effectively extinguished in several ways: methylation of the most acidic imidazolium ring proton, replacing the imidazolium 3-methyl group with a longer hydrocarbon chain, substitution of [BOB]⁻ by [BMB]⁻, or exchanging the imidazolium for phosphonium systems, irrespective of phosphonium architecture. The results suggest there is only a small window of opportunity, in terms of molecular amphiphilicity and cation:anion volume matching, for the formation of stable extensive bicontinuous domains in pure bulk orthoborate-based ILs. Particularly important for self-assembly processes appear to be the ability to form H-bonding networks, which offer additional versatility in imidazolium systems.