Synthesis and Characterization of Chromium Hexacyanoferrate/Multiwalled Carbon Nanotube Composite and Its Biosensing for L‐Cysteine

This work describes the electrochemical properties of glassy carbon electrodes (GCE) modified with chromium(III) hexacyanoferrate(II) (Crhf) nanoparticles attached multiwalled carbon nanotube (MWNTs). The morphological characterization of Crhf/MWNTs nanocomposites was examined by scanning electron microscopy (SEM), UV‐vis spectroscopy, and Fourier transform infrared spectrometry (FT‐IR). The electrocatalytic activity of these nanocomposites was investigated and showed a good electrocatalytic effect for oxidation of L ‐cysteine (L ‐Cys) in 0.1 M phosphate buffer solution (pH 3.0). Under optimum conditions linear calibration graphs were obtained over the L ‐Cys concentration range 5.0×10^?7 to 6.0×10^?5 M with a correlation coefficient of 0.9998 and a detection limit (signal‐to‐noise ratio was 3) of 1.0×10^?8 M. The proposed method is simple and it also showed excellent sensitivity and stability. The excellent electrocatalytic ability of the modified electrode towards L ‐Cys manifests that the Crhf/MWNTs can provide a new platform for biosensors and other biology.     

Communication: Experimental proof of symmetry breaking in tilted smectics composed of molecules with axial chirality

For the first time, domains with twisted structures have been established in planar samples of achiral compounds in tilted smectic C phase. This evidences separation of molecular conformers differing in the sense of axial chirality and confirms polar C(2) symmetry of these domains. A simple model considering polar surface anchoring energy and bulk energy of the twist can account for this finding. Conditions for coexistence of twisted and homogeneous domains are discussed.     

Sesquiterpenes and Other Metabolites from the Marine Red Alga Laurencia composita (Rhodomelaceae)

Two new halogenated sesquiterpenes, (8β)‐10‐bromo‐3‐chloro‐2,7‐epoxychamigr‐9‐en‐8‐ol ( 1 ) and 2‐bromo‐3‐chlorobisabola‐7(14),11‐diene‐6,10‐diol ( 3 ), and one new phytol‐derived diterpene, 2,3‐epoxyphytyl acetate ( 4 ), along with cis‐ and trans‐1‐methylcyclohexane‐1,4‐diol ( 5 and 6 ) which were isolated from a natural source for the first time but have been previously synthesized, were isolated from the marine red alga Laurencia composita and characterized. In addition, a known sesquiterpene, pacifenediol ( 2 ), and the known furanone derivative 7 were also identified. Their structures were established by NMR and mass spectroscopic methods.     

New Epoxy‐Substituted Nitrogenous Bisabolene‐Type Sesquiterpenes from a Hainan Sponge Axinyssa sp.

Two new uncommon epoxy‐substituted nitrogenous bisabolene‐type sesquiterpenes, 3‐formamido‐7,8‐epoxy‐α‐bisabolane ( 4 ), 3‐isocyano‐7,8‐epoxy‐α‐bisabolane ( 5 ), together with three known related sesquiterpenes, 1 – 3 , were isolated from the Hainan sponge Axinyssa sp. Their structures were determined on the basis of extensive spectroscopic analyses and by comparison of their NMR data with those of structurally related compounds.     

Five New C19‐Diterpenoid Alkaloids from Aconitum hemsleyanum

Five new C₁₉‐diterpenoid alkaloids, named hemsleyaconitines A–E ( 1 – 5 , resp.), were isolated from Aconitum hemsleyanum Pritz. By UV, IR, MS, 1D‐ and 2D‐NMR analyses, their structures were elucidated as 18‐dehydroxygeniculatine D ( 1 ), 6‐hydroxy‐14‐O‐veratroylneoline ( 2 ), 14‐O‐acetyl‐8‐ethoxysachaconitine ( 3 ), 18‐veratroylkaracoline ( 4 ) and 8‐O‐ethylaustroconitine B ( 5 ).     

Highly efficient aerobic oxidation of oximes to carbonyl compounds catalyzed by metalloporphyrins in the presence of benzaldehyde

Highly efficient oxidation of oximes to carbonyl compounds by molecular oxygen with benzaldehyde as an oxygen acceptor in the presence of metalloporphyrins has been reported. The simple structural manganese porphyrin showed an excellent activity for the oxidative deoximation reactions of various oximes. Moreover, different factors influencing oximes oxidation, that is, catalyst, solvent, and temperature, have been investigated. A possible mechanism for the deoximation reaction has been proposed.     

Synthesis of phenothiazine-corrole dyads: the enhanced DNA photocleavage properties

Three new phenothiazine-corrole dyads were prepared by the reaction of phenothiazine-10-carbonyl chloride and mono-hydroxyl triaryl corrole in the presence of DBU. As compared to corrole monomer, these phenothiazine-corrole dyads exhibit significant enhanced DNA photocleavage activity as compared to corrole monomer precursors.     

Cyclopropanation of nitroso Diels-Alder cycloadducts and application to the synthesis of a 2′,3′-methano carbocyclic nucleoside

Treatment of nitroso Diels-Alder cycloadducts 1 with diazomethane in the presence of palladium acetate gives synthetically useful exo-6-oxa-7-azatricyclo[3.2.1.0^2,4]octane derivatives 7 in good to excellent yield. Using this methodology, a conformationally restricted 2′,3′-methano carbocyclic nucleoside was efficiently synthesized from nitroso cycloadduct 1a in seven steps.     

[Cd2(tren)2(dl-alaninato)](ClO4)3: an efficient water-compatible Lewis acid catalyst for chemo-, regio-, and diastereo-selective allylation of various aldehydes

The use of [Cd₂(tren)₂(dl-alaninato)](ClO₄)₃·H₂O (I) (tren = tris(2-aminoethyl)amine) as an efficient water-compatible Lewis acid catalyst for the allylation of aldehydes in aqueous media was described. The reaction proceeded smoothly to afford the corresponding homoallyl alcohols in up to 96% yield. Additionally, cinnamyltributylstannane was selected as the allylation reagent, the regio- and diastereoselectivity of the reaction favors the formation of the γ-product and the anti isomers, respectively.     

{[Eu(ox)(H2O)4]·[CuBr(2‐pzc)2]·4H2O}: Hydrogen Bonding Directed Assembly to Supramolecular Network

A new 3d–4f heterometallic coordination framework, {[Eu(ox)(H₂O)₄] · [CuBr(2‐pzc)₂] · 4H₂O} ( 1 ) [ox = oxalate; 2‐pzc = pyrazine‐2‐carboxylate] was synthesized and characterized by elemental analysis, IR spectroscopy and thermal analysis, as well as single‐crystal X‐ray diffraction. Complex 1 represents one 3D supramolecular heterometallic coordination framework that is assembled from rare lanthanide‐ox anionic chains and CuBr(2‐pzc)₂ cationic units through hydrogen bonds.