Contrasting reductions of group 14 metal(II) chloride complexes: synthesis of a β-diketiminato tin(I) dimer

Reductions of the β-diketiminato group 14 metal(II) chloride complexes, [((But)MesNacnac)ECl] ((But)MesNacnac = [(MesNCBu(t))(2)CH](-); Mes = mesityl; E = Ge, Sn or Pb), with a magnesium(I) dimer have led to differing outcomes, which include the formation of the first β-diketiminato group 14 metal(I) dimer, [{((But)MesNacnac)Sn}(2)].     

Topological quantum phase transition in 5d transition metal oxide Na2IrO3

We predict a quantum phase transition from normal to topological insulators in the 5d transition metal oxide Na2IrO3, where the transition can be driven by the change of the long-range hopping and trigonal crystal field terms. From the first-principles-derived tight-binding Hamiltonian, we determine the phase boundary through the parity analysis. In addition, our first-principles calculations for Na2IrO3 model structures show that the interlayer distance can be an important parameter for the existence of a three-dimensional strong topological insulator phase. Na2IrO3 is suggested to be a candidate material which can have both a nontrivial topology of bands and strong electron correlations.     

<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.     

A lipidomic platform establishment for structural identification of skin ceramides with non-hydroxyacyl chains

The stratum corneum (SC) is the outermost layer of skin that functions as a barrier and protects against environmental influences and transepidermal water loss. Its unique morphology consists of keratin-enriched corneocytes embedded in a distinctive mixture of lipids containing mainly ceramides, free fatty acids, and cholesterol. Ceramides are sphingolipids consisting of sphingoid bases, which are linked to fatty acids by an amide bond. Typical sphingoid bases in the skin are composed of dihydrosphingosine (dS), sphingosine (S), phytosphingosine (P), and 6-hydroxysphingosine (H), and the fatty acid acyl chains are composed of non-hydroxy fatty acid (N), α-hydroxy fatty acid (A), ω-hydroxy fatty acid (O), and esterified ω-hydroxy fatty acid (E). The 16 ceramide classes include several combinations of sphingoid bases and fatty acid acyl chains. Among them, N-type ceramides are the most abundant in the SC. Mass spectrometry (MS)/MS analysis of N-type ceramides using chip-based direct infusion nanoelectrospray-ion trap mass spectrometry generated the characteristic fragmentation pattern of both acyl and sphingoid units, which could be applied to structural identification of ceramides. Based on the MS/MS fragmentation patterns of N-type ceramides, comprehensive fragmentation schemes were proposed. In addition, mass fragmentation patterns, which are specific to the sphingoid backbone of N-type ceramides, were found in higher m/z regions of tandem mass spectra. These characteristic and general fragmentation patterns were used to identify N-type ceramides in human SC. Based on established MS/MS fragmentation patterns of N-type ceramides, 52 ceramides (including different classes of NS, NdS, NP, and NH) were identified in human SC. The MS/MS fragmentation patterns of N-type ceramides were characterized by interpreting their product ion scan mass spectra. This information may be used to identify N-type ceramides in the SC of human, rat, and mouse skin.     

Formation of Stable Solvent-trapped Carbonyl Oxides from the Ozonolysis of Indole Derivatives

Ozonolyses of ethyl indole-2-carboxylate (1a) and ethyl 1-methylindole-2-carboxylate (1b) in participating solvent, methanol, afforded α-methoxyhydroperoxides 7a and 7b in 90% and 89% yields, respectively, which are the first isolated solvent-trapped carbonyl oxides from ozonolysis of indole derivatives.     

Structural evolution of irreversibly adsorbed Bi on Pt(111) under potential excursion

This work presents a structural evolution of irreversibly adsorbed Bi on Pt(111) studied by electrochemical scanning tunneling microscopy and electrochemistry. The irreversibly adsorbed Bi showed a stable redox couple at 0.33 V whose maximum charge corresponded to the coverage of 0.33. The pristine layer of irreversibly adsorbed Bi grew from islands to large domains of the first monolayer, eventually to large domains of the monolayer with scattered protrusions of the second layer. During an electrochemical treatment from open circuit potential (～0.25 V) to 0.1 V, the domains of the pristine Bi layer shrunk and the Bi in the second layer moved to the first layer to form a compressed layer of elemental Bi. When the elemental Bi was re-oxidized at 0.35 V, there was no structural change to denote that the structures of the pristine and re-oxidized layers of oxygenated Bi differ from each other. The structural evolution during the electrochemical treatments is discussed in terms of removal and reinsertion of oxygen species.     

Co-deposits of Pt and Bi on Au disk toward formic acid oxidation

Journal of Solid State Electrochemistry - Presented in this work is an investigation of co-deposits of Pt and Bi on Au disk (Pt-Bi/Au) toward formic acid oxidation (FAO) using voltammetry and X-ray...     

N-heterocyclic carbene-catalysed intermolecular Stetter reactions of acetaldehyde

A facile method for the intermolecular Stetter reaction of various Michael acceptors with acetaldehyde as a biomimetic acylanion source was realized using N-heterocyclic carbene catalysis. This catalytic system has also been applied to the enantioselective Stetter reaction and resulted in moderate to good enantioselectivities for the corresponding Stetter products.     

Effect of five-membered heteroaromatic linkers to the performance of phenothiazine-based dye-sensitized solar cells

Phenothiazine derivatives with various conjugated linkers (furan, thiophene, and 3,4-ethylenedioxythiophene) were synthesized and used in dye-sensitized solar cells to study the effect of conjugated linkers on device performance. Among them, one with furan as a conjugated linker showed a solar energy-to-electricity conversion efficiency (η) of 6.58%, an improvement of over 24% compared with the T2-1 reference cells' 5.29% under AM 1.5 G irradiation.