Isotopic and Isotonic Chains of Nuclei in the 2p−1f−1gRegion in the Relativistic Mean Field Approach

A complete systematic set of relativistic mean field calculations are presented for the 2p−1f−1gshell nuclei with 28Z40; 26N50, both for isotopic and isotonic chains. Two sets of Lagrangian parameters NL1 (most successfully used in the past) and NL-SH (recently proposed) are used. Also sensitivity of the calculated results on the gaps required to account for pairing is investigated. The calculated binding energies, one (two) nucleon separation energies, the deformations and quadrupole moments, the point and the charge radii, isotopic shifts, densities, alpha staggering and the related quantities are systematically analyzed. The calculations are in good agreement with the experiment. The set Nl-SH seems to have an edge over the set NL1 especially for the neutron rich nuclei.     

An unusual stereochemical outcome of radical cyclization: synthesis of (+)-biotin

An enantioselective synthesis of (+)-biotin 1 starting from naturally available cysteine is described. The key steps are the unusual stereochemical outcome of radical cyclization of compound 10 to prepare 5,5-fused system 11, and the introduction of C4-sidechain at C₆ in 13 via a Grignard reaction.     

Synthesis,characterization, and antibacterial activity of 6-Chloro-8-methyl-2-oxo-2H-chromene-3-carboxylic acid ethyl ester

The title compound was synthesized by reacting 2-hydroxy-4-methoxy-benzaldehyde with diethyl malonate in the presence of piperidine catalyst and ethanol as solvent. The chemical structure of the title compound was elucidated by elemental analysis, ¹H-NMR, and IR. The crystal structure was determined by X-ray diffraction data. It crystallizes in monoclinic crystal system, P2₁/c space group with unit cell parameters, a = 12.840(2) Å, b = 24.790(4) Å, c = 7.8544(13) Å, β = 98.035(5)°, V = 2475.5(7) ų, and Z = 8. The molecular and crystal structure of the title compound is stabilized by inter- and intramolecular interactions of the type C—H···O. The newly synthesized compound was screened for its antibacterial activity against two gram-positive and two gram-negative bacteria.     

Multiply Charged Anions,Maximum Charge Acceptance,and Higher Electron Affinities of Molecules,Superatoms,and ClustersSCI北大核心CSCD

The addition of electrons to form gas-phase multiply charged anions (MCAs) normally requires sophisticated experiments or calculations.In this work, the factors stabilizing the MCAs, the maximum electron uptake of gas-phase molecules, X, and the electronic stability of MCAs X^Q-, are discussed. The drawbacks encountered when applying computational and/or conceptual density functional theory (DFT) to MCAs are highlighted. We develop and test a different model based on the valence-state concept. As in DFT, the electronic energy, E(N, v_ex), is a continuous function of the average electron number, N, and the external potential, v_ex, of the nuclei. The valence-state-parabola is a second-order polynomial that allows extending E(N, v_ex) to dianions and higher MCAs. The model expresses the maximum electron acceptance, Q_max, and the higher electron affinities, A_Q, as simple functions of the first electron affinity, A₁, and the ionization energy, I, of the "ancestor" system. Thus, the maximum electron acceptance is Q_{max, calc} = 1 + 12A₁/7(I -A₁). The ground-state parabola model of the conceptual DFT yields approximately half of this value, and it is termed Q_{max, GS} = ${}^{1}\!\!\diagup\!\!{}_{2}\; $ + A₁/(I -A₁). A large variety of molecules are evaluated including fullerenes, metal clusters, super-pnictogens, super-halogens (OF₃), super-alkali species (OLi₃), and neutral or charged transition-metal complexes, AB_mL_n^0/+/-. The calculated second electron affinity A_{2, calc} = A₁-(7/12)(I -A₁) is linearly correlated to the literature references A_{2, lit} with a correlation coefficient R = 0.998. A₂ or A₃ values are predicted for further 24 species. The appearance sizes, n_ap^3-, of triply charged anionic clusters and fullerenes are calculated in agreement with the literature.     

Facile fabrication of visible light-driven CeO<Subscript>2</Subscript>/PMMA thin film photocatalyst for degradation of CR and MO dyes

CeO₂/PMMA NCTF was successfully fabricated by a facile, room-temperature, inexpensive, and simple solution casting method. Ultra-violet, Fourier-transform infrared spectroscopy, X-ray diffraction spectroscopy, scanning electron microscopy, energy dispersive X-ray spectroscopy, transmission electron microscopy and X-ray photoelectron spectroscopy techniques have been used to scrutinize the structure and properties of CeO₂/PMMA NCTF. It has been found that the CeO₂ nanocubes are constantly dispersed into the PMMA matrix thus forming a thin film. Due to its unique structure, the CeO₂/PMMA NCTF has enhanced activity and selectivity towards the visible light-driven degradation of various organic pollutants. The photocatalytic degradation efficiency of the catalyst was tested against Congo red and methyl orange, selected as model organic contaminants. The synergistic effect of the catalyst reduces the electron–hole recombination rate and thus enhances the photocatalytic activity. Hydroxyl radical and super oxide radical ion species induce the photocatalysis which can be determined by trapping experiments. The synthesized CeO₂/PMMA NCTF can be reused several times without loss of activity, and a plausible mechanism was also proposed. It is hoped that our present effort may inspire further studies in new, efficient, recyclable photocatalysts and the degradation of organic contaminants driven by visible light.     

Oxidative Addition of Dimethyl Malonate to Styrenes Mediated by Cerium(Iv) Ammonium Nitrate: Some Novel Observations

The oxidative addition of dimethyl malonate to ring substituted styrenes leads to the formation of substituted dimethyl (2-oxo-2-phenylethyl) malonate and methyl 2-oxo-5-phenyltetrahydrofuran-3-carboxylate along with small amounts of substituted dimethyl [2-(nitrooxy)-2-phenylethyl] malonate and dimethyl 2-methoxy-2-phenylethyl) malonate. A tentative mechanism which supports the formation of these products is also presented.     

Total synthesis of (+)-spiroindimicin A and congeners unveils their antiparasitic activity

The spiroindimicins are a unique class of chlorinated indole alkaloids characterized by three heteroaromatic rings structured around a congested spirocyclic stereocenter. Here, we report the first total synthesis of (+)-spiroindimicin A, which bears a challenging C-3′/C-5′′-linked spiroindolenine. We detail our initial efforts to effect a biomimetic oxidative spirocyclization from its proposed natural precursor, lynamicin D, and describe how these studies shaped our final abiotic 9-step solution to this complex alkaloid built around a key Pd-catalyzed asymmetric spirocyclization. Scalable access to spiroindimicins A, H, and their congeners has enabled discovery of their activity against several parasites relevant to human health, providing potential starting points for new therapeutics for the neglected tropical diseases leishmaniasis and African sleeping sickness.

Spiroindimicins A and H have been synthesized for the first time via a key palladium-catalyzed spirocyclization. Access to these alkaloids and several congeners has allowed the discovery of their antiparasitic properties.     

<em>Cassia spectabilis </em>(DC) Irwin et Barn: A Promising Traditional Herb in Health Improvement

The genus Cassia, comprising about 600 species widely distributed worldwide is well known for its diverse biological and pharmacological properties. Cassia spectabilis (sin Senna spectabilis) (DC) Irwin et Barn (Fabaceae) is widely grown as an ornamental plant in tropical and subtropical areas. C. spectabilis has been commonly used in traditional medicine for many years. Information in the biomedical literature has indicated the presence of a variety of medicinally-important chemical constituents in C. spectabilis. Pharmacological studies by various groups of investigators have shown that C. spectabilis possesses significant biological activity, such as antibacterial, antibiofilm, antifungal and antioxidant properties. Beside this, toxicity studies of this plant have revealed no toxic effect on mice. In view of the immense medicinal importance of C. spectabilis, this review aimed at compiling all currently available information on C. spectabilis's botany, phytochemistry, pharmacology, and mechanism of actions, toxicology and its ethnomedicinal uses.