Inventory of <Superscript>129</Superscript>I in brackish lake sediments adjacent to a spent nuclear fuel reprocessing plant in Japan

In this study, four fruit’s seed samples as Punica granatum L., Citrus medica var. limonum, Malus domestica L. and Citrus vulgaris Risso were prepared from Arak’s markets. They were analyzed using instrumental neutron activation method (INAA). In this method, Tehran research reactor as a neutron source and relative INAA method has been used as the analysis method and to record gamma ray spectrum, the high purity germanium detector was used. Pomegranate seeds had the highest number of essential elements. Apple seeds and sour orange seeds contain the highest levels of Mg and K, Respectively.     

Determination of Chlorogenic Acid in a Herbal Medicinal Product with Preconcentration by Ionic Liquid-Modified Magnetic Nanoparticles and High-Performance Liquid Chromatography

Magnetic nanoparticles (MNPs) have been widely used in herbal analysis, and potential ionic liquid-based MNPs are expected in similar applications. In this study, the new functional Fe₃O₄ nanoparticles combined with a previously unreported ionic liquid were synthesized by three methods and used to enrich chlorogenic acid from aqueous solution and crude herbal extracts for the first time. The combination of pyrrole cation and proline anion immobilized on Fe₃O₄ nanoparticles had higher immobilized concentrations and ideal morphology, which can be easily adsorbed and recovered by an external magnetic field from the nanosuspension. When the mobile phase composed of acetonitrile and 0.5% phosphate aqueous solution (3:22, v:v) was used on a C₁₈ chromatographic column (4.6?×?250?mm, 5?µm) at 25°C, the concentration of chlorogenic acid in herbal product was determined to be 7.01?mg/g. The validation indicated the method had good linearity, recovery, repeatability, and precision. These results show that the ionic liquid has been chemically bonded to the magnetic nanoparticles through the developed procedures and may be effectively used for the high-performance liquid chromatographic determination of chlorogenic acid in herbal products.     

A highly efficient reusable homogeneous copper catalyst for the selective aerobic oxygenation sulfides to sulfoxides

Readily available copper showed efficient activity and great selectivity for the homogeneous catalysis of oxidation of sulfides to sulfoxides using molecular oxygen as the oxidant. The reaction proceeds under mild conditions in the presence of a catalytic amount of TEMPO. Importantly, the catalysts could be conveniently recovered and reused. And this methodology was proved to be applicable for the transformation of various aromatic and aliphatic sulfides into the corresponding sulfoxides with high conversion and high selectivity.     

Synthesis of polyfunctionalized pyrroles bearing C-2 α-azido side-chains and displacement of the α-azido group by various nucleophiles

Tetrasubstituted pyrroles bearing C-2 α-azido side-chains were synthesized employing a new class of diazides, α,γ-diazido α,β-unsaturated esters, and 1,3-dicarbonyl compounds under simple thermal conditions. Further investigation of the synthetic utility of the obtained pyrroles reveals unexpected displacement of the α-azido group at the C-2 side-chain by a variety of nucleophiles. This two-step process exhibits a broad substrate scope, good functional group tolerance, simple operation, and high reaction efficiency, providing an easy access to polyfunctional pyrroles with novel substitution patterns.     

Molecular Recognition by a Short Partial Peptide of the Adrenergic Receptor: A Bottom‐Up Approach

Receptor–neurotransmitter molecular recognition is key for neurotransmission. Although crystal structures of the receptors are known, the mechanism for recognition is not clear. Reported here is the ultraviolet (UV) and infrared (IR) spectra of complexes between a partial peptide (SIVSF), mimicking the binding motif of a catechol ring in the adrenergic receptor, and various ligands. The UV spectra show that two isomers coexist in the complex of SIVSF with properly recognized ligands, such as protonated adrenaline (adrenalineH⁺). From IR spectra, they are assigned to catechol‐ and amino‐bound structures. The catechol‐bound structure is not observed when the ligand is replaced by nonproper molecules, such as noradrenalineH⁺. The results suggest that SIVSF not only recognizes the catechol ring but can distinguish differences in the amine side chain. The method provides a new possibility for screening molecules as potential therapeutics for activating the receptor.     

Directional Shuttling of a Stimuli‐Responsive Cone‐Like Macrocycle on a Single‐State Symmetric Dumbbell Axle

Rotaxane‐based molecular shuttles are often operated using low‐symmetry axles and changing the states of the binding stations. A molecular shuttle capable of directional shuttling of an acid‐responsive cone‐like macrocycle on a single‐state symmetric dumbbell axle is now presented. The axle contains three binding stations: one symmetric di(quaternary ammonium) station and two nonsymmetric phenyl triazole stations arranged in opposite orientations. Upon addition of an acid, the protonated macrocycle shuttles from the di(quaternary ammonium) station to the phenyl triazole binding station closer to its butyl groups. This directional shuttling presumably originates from charge repulsion and an orientational binding preference between the cone‐like cavity and the nonsymmetric phenyl triazole station. This mechanism for achieving directional shuttling by manipulating only the wheels instead of the tracks is new for artificial molecular machines.     

Structural,Electronic and Tunable Magnetic Properties of Transition Metal Doped Rh<Subscript>8</Subscript> Cluster from First Principles Calculation

The configurations, electronic and magnetic properties of the Rh₇M (M?=?3d, 4d transition metal) are systematically investigated within the framework of the generalized gradient approximation density-functional theory (DFT-GGA). The results indicated that the ground state structures of Rh₇M (M?=?3d) clusters prefer to a bicapped octahedron configuration, while the Rh₇M (M?=?4d) clusters present a different degree of geometry reconstruction relative to the perfect cubic structure of Rh₈ cluster. In most cases, the doped clusters show relatively higher stability, indicating that impurity atoms could stabilize the pure Rh₈ cluster; the Rh₇M (M?=?3d, 4d) have smaller frontier orbital energy gaps in comparison to the host. The magnetic moments of Rh₇M (M?=?3d, 4d) exhibit a tunable magnetism with range from 3μ_B to 13μ_B and the Fe atom doping enhances the magnetic moment of mixed cluster.     

Probing Interfacial Electronic and Catalytic Properties on Well‐Defined Surfaces by Using In Situ Raman Spectroscopy

Heterogeneous metal interfaces play a key role in determining the mechanism and performance of catalysts. However, in situ characterization of such interfaces at the molecular level is challenging. Herein, two model interfaces, Pd and Pt overlayers on Au single crystals, were constructed. The electronic structures of these interfaces as well as effects of crystallographic orientation on them were analyzed by shell‐isolated nanoparticle‐enhanced Raman spectroscopy (SHINERS) using phenyl isocyanide (PIC) as a probe molecule. A clear red shift in the frequency of the C≡N stretch (ν_NC) was observed, which is consistent with X‐ray photoelectron spectroscopy (XPS) data and indicates that the ultrathin Pt and Pd layers donate their free electrons to the Au substrates. Furthermore, in situ electrochemical SHINERS studies showed that the electronic effects weaken Pt?C/Pd?C bonds, leading to improved surface activity towards CO electrooxidation.     

Magnetoluminescence in a Photostable,Brightly Luminescent Organic Radical in a Rigid Environment

We investigated the emission properties of a photostable luminescent organic radical, (3,5‐dichloro‐4‐pyridyl)bis(2,4,6‐trichlorophenyl)methyl radical (PyBTM), doped into host molecular crystals. The 0.05 wt %‐doped crystals displayed luminescence attributed to a PyBTM monomer with a room‐temperature emission quantum yield of 89 %, which is exceptionally high among organic radicals. The 10 wt %‐doped crystals exhibited both PyBTM monomer and excimer‐centered emission bands, and the intensity ratio of these two bands was modulated drastically by applying a magnetic field of up to 18 T at 4.2 K. This is the first observation of a magnetic field affecting the luminescence of organic radicals, and we also proposed a mechanism for this effect.