Characteristics of magnetism in nanoporous carbon with palladium clusters

The magnetic properties of samples of nanoporous carbon with palladium clusters prepared from polycrystalline SiC have been studied over a wide range of temperatures. The specific magnetic moment rapidly decreases with increasing temperature. The obtained experimental magnetization curves have a nonlinear character but do not reach saturation even in a field of 10 kOe. Being constructed as functions of H/T, they lie on a universal curve, which suggests superparamagnetism of the system. The experimental curves have a hysteresis. The coercive force, first, decreases with increasing temperature and, then (in the range of 5–20 K), increases, thus forming a notch singularity. On the contrary, the residual magnetization rapidly decreases with increasing temperature. A conclusion on the prevailing contribution of superparamagnetic clusters to the magnetic subsystem is made.     

Specific features of the EPR spectra of KTaO<Subscript>3</Subscript>: Mn nanopowders

The electron paramagnetic resonance spectra of KTaO₃: Mn nanocrystalline powders in the temperature range from 77 to 620 K have been measured and studied for the first time. The change observed in the spectra has been investigated as a function of the doping level. The doping regions in which Mn²⁺ ions are individual paramagnetic impurities have been established, as well as the regions where the dipole-dipole and exchange interactions of these ions begin to occur. The spin-Hamiltonian constants for the spectrum of non-interacting individual Mn²⁺ ions have been determined as follows: g = 2.0022, D = 0.0170 cm⁻¹, and A = 85 × 10⁻⁴ cm⁻¹. A significant decrease in the axial constant D in the KTaO₃: Mn nanopowder, as compared to the single crystal, has been explained by the remoteness of the charge compensator from the paramagnetic ion and by the influence of the surface of the nanoparticle. It has been assumed that the Mn²⁺ ions are located near the surface and do not penetrate deep into the crystallites.     

Modulating N- versus O-arylation in pyrazolone-aryl halide couplings

The regioselective, copper-catalyzed coupling of a tautomeric pyrazolone/pyrazole with 2-halopyridines was investigated. Conditions were developed to preferentially form either the N-aryl or O-aryl product.     

Synthesis and Anti‐proliferative Activity of N,N′‐bis‐substituted 1,2,4‐Triazolium Salts against Breast Cancer and Prostate Cancer Cell Lines

A series of 1,4‐N,N′‐bis‐substituted 1,2,4‐triazolium bromide salts were synthesized and tested for anti‐proliferative activity. 1,4‐Bis(naphthalen‐2‐ylmethyl)‐1,2,4‐triazolium bromide ( 2 ) showed activity against MDA‐MB‐468 breast cancer and PC‐3 prostate cancer cell lines.     

Druggable Allosteric Sites in β-Propeller Lectins

Carbohydrate-binding proteins (lectins) are auspicious targets in drug discovery to combat antimicrobial resistance; however, their non-carbohydrate drug-like inhibitors are still unavailable. Here, we present a druggable pocket in a β-propeller lectin BambL from Burkholderia ambifaria as a potential target for allosteric inhibitors. This site was identified employing ¹⁹F NMR fragment screening and a computational pocket prediction algorithm SiteMap. The structure–activity relationship study revealed the most promising fragment with a dissociation constant of 0.3±0.1 mM and a ligand efficiency of 0.3 kcal mol^?1 HA^?1 that affected the orthosteric site. This effect was substantiated by site-directed mutagenesis in the orthosteric and secondary pockets. Future drug-discovery campaigns that aim to develop small molecule inhibitors can benefit from allosteric sites in lectins as a new therapeutic approach against antibiotic-resistant pathogens.     

Donor–Acceptor Bond in Nontransition and Transition Element Complexes: Studies with Natural Bonding Orbital Approach

Electronic structures of tin, antimony, titanium, and niobium chloride complexes were analyzed using density functional theory. Parameters of nuclear quadrupole resonance spectra calculated using pseudopotential and all-electron basis states were compared with the experimental values. It was shown that the use of the central atom pseudopotential leads to a significant deviation of the atomic quadrupole coupling constants from their experimental values. The bonding in complexes was analyzed by making use of the natural orbitals of metal–chlorine and metal–ligand bonds. Donor–aceptor interactions in complexes of main group elements are described within the framework of sp-hybridization, while those in the transition element complexes, within the sd-hybridization framework.