Chelator-free radiolabeling of dextran with 68Ga for PET studies

Journal of Radioanalytical and Nuclear Chemistry - The possibility of 68Ga-dextran complex formation was analyzed in an HEPES-buffered (pH = 4.5) as well as in an alkaline...     

Quantitative TLC of Toxic Elements on Inorganic Ion-exchangers. VI. Separation and Determination of Cadmium

JPC – Journal of Planar Chromatography – Modern TLC -     

[Bmim]NO2/H3BO3 as an effective nitrosonium source for electrophilic aromatic nitrosation under MW-promoted solvent-free conditions

[Bmim]NO₂/H₃BO₃ was used as a nitrosonium source for the efficient synthesis of nitrosoarenes. The reaction was accomplished under MW irradiation at 60 W in a solventless system. Side processes such as oxidation or dealkylation were not observed during the nitrosation of alkyl phenyl ethers in the presence of this new reagent. The satisfactory results were obtained with very short reaction time, simplicity in the experimental procedure and good to excellent yields.     

Revealing substituent effects on the concerted interaction of pnicogen, chalcogen, and halogen bonds in substituted s-triazine ring

Quantum chemical calculations have been performed to gauge the effect of substituents on concerted interactions of pnicogen, chalcogen, and halogen bonds in the X–TAZ···Y complexes (X = CN, F, Cl, Br, H, CH₃, OH, and NH₂, where TAZ and Y denote s-triazine ring and P, S, and Cl atoms, respectively) at the M06-2X/aug-cc-pVDZ level. The mutual interplay of these interactions is also investigated. The results indicate that diminutive effects are observed when the three kinds of noncovalent interactions pnicogen, chalcogen, and halogen bonds are coexisted in the complexes. These effects are studied in terms of energetic and geometric features of the complexes. In addition, Bader’s theory of “atoms in molecules” is used to analyze their strength of varying electron density at bond critical points. Natural bond orbital (NBO) theory is used to characterize the orbital interactions. The results indicate that the electron-withdrawing/donating substituents decrease/increase the magnitude of the binding energies compared to the unsubstituted X–TAZ···Y (X = H) complex. Good correlations among binding energies, Hammett constants, geometrical, atoms in molecular and NBO parameters are established in X–TAZ···Y complexes. By taking advantage of all the aforementioned computational methods, this study examines how these interactions mutually influence each other.     

Borazine-based conjugated derivatives: Structural,electronic, and optical properties

The structural characteristics, electronic properties, and nonlinear optical properties of borazine-based conjugated derivatives have been explored at B3LYP/6-311G(d,p) level. The effects of various electron donor and acceptor substituents (H, F, Cl, Br, Me, CF₃, NH₂, OH, COOH, CHO, NO₂) on the structure, polarizability, frontier orbitals, the most intense electronic transition, and hyperpolarizabilities have studied. Calculations show that NO₂-substituted molecules have lowest hardness, the largest isotropic polarizability and anisotropy of polarizability, and first hyperpolarizability.     

Nitrite Ionic Liquids (IL‐ONO and [bmim]NO2) as Effective Nitrosonium Sources for the Synthesis of α‐Oximinoketones under Mild Heterogeneous Conditions

Ketones and β‐diketones were nitrosated and converted to their corresponding α‐oximinoketones using task‐specific ionic liquids, 1‐(4‐nitritobutyl)‐3‐methylimidazolium chloride, IL‐ONO, and 1‐butyl‐3‐methylimidazolium nitrite at room temperature. The results from two ionic liquids are comparable and showed that these IL's are effective nitrosonium sources for the preparation of oximinoketones. The protocol is rapid, the yields are excellent, and the method is simple.     

Ionic liquid 1-(4-nitritobutyl)-3-methylimidazolium chloride as a new reagent for the efficient N-nitrosation of secondary amines under mild conditions

Abstract  

1-(4-Nitritobutyl)-3-methylimidazolium chloride has been developed as a new reagent for efficient nitrosation of secondary amines at 0 °C to room temperature. A variety of N-nitrosamines were prepared in excellent yields by use of this task-specific ionic liquid under mild and heterogeneous conditions.     

Interaction between uracil nucleobase and phenylalanine amino acid: the role of sodium cation in stacking

The stacking interactions in the uracil:phenylalanine (U:PHE) and (U:PHE)···Na⁺ complexes have been studied at different levels of theory, in which the structures were optimized by both standard and gradient counterpoise corrected methods. The Na⁺ cation can interact with different sites of stacked U:PHE unit. The geometrical parameters of the optimized structures and the calculated binding energies reveal the influence of cation interaction on π–π stacking and vice versa. The interplay between π–π stacking and cation interaction has also been investigated by topological analysis of electron charge density using atoms in molecules (AIM) method. A good agreement between the results of AIM analysis and calculated binding energies has been observed in dimer and complexes.