A Ce(III)-catalyzed expeditious multicomponent stereoselective synthesis of 3-mercapto-2(1H)-pyridinones

A novel Ce(III)-catalyzed, convenient, expeditious, and diastereoselective synthesis of 3-mercapto-2(1H)-pyridinones via one-pot, [3+2+1] three-component coupling reactions of chalcones, 2-methyl-2-phenyl-1,3-oxathiolan-5-one, and amines is reported. The synthesis involves sequential Michael addition, condensation, and ring transformation. Ambient temperature, operational simplicity, use of an environmentally clean catalyst, high yields, and diastereoselectivity are the key features of the present synthetic protocol.     

Bulk heterojunction solar cells based on self-assembling disc-shaped liquid crystalline material

In this article, effect of addition of disc-shaped liquid crystalline material, namely 2, 3, 6, 7, 10, 11-hexabutyloxytriphenylene, in poly (3-hexylthiophene): [6, 6]-phenyl-C61-butyric acid methyl ester containing bulk heterojunction (BHJ) solar cells has been investigated. These disc-shaped molecules organise into ordered columnar hexagonal structures through intermolecular π ? π interactions as monitored by polarised light optical microscopy. Current–voltage characteristics of the device prepared with liquid crystal layer exhibited a short-circuit current of 10.5 mA cm^?2 and a fill factor of 35%. The resultant power conversion efficiency (PCE) was 1.54%. The influence of varying the thickness of liquid crystal layer and annealing on these solar cells was also studied. The short circuit current and PCE of 12.9 mA cm^?2 and 2.3% was achieved for these BHJ solar cells containing self-organised discotic liquid crystals in the active layer under one sun condition after annealing.     

Synthesis of a tetrasaccharide related to the triterpenoid saponin isolated from Schima noronhae

A concise synthesis of a tetrasaccharide related to the cell-growth inhibitory triterpenoid saponin isolated from Schima noronhae is reported. A late stage 2,2,6,6-tetramethylpiperidinyloxy (TEMPO)-mediated oxidation of a primary hydroxyl group to carboxylic acid has been achieved under phase-transfer conditions. Stereoselective glycosylations were carried out using thioglycoside or glycosyl trichloroacetimidate activation using sulfuric acid immobilized on silica (H₂SO₄–silica) in conjunction with N-iodosuccinimide and alone, respectively.     

Synthesis of Some New 2‐Oxo‐N‐[(10H‐phenothiazin‐10‐yl)alkyl] Derivatives of Azetidine‐1‐carboxamides

The synthesis of a new series of 4‐aryl‐3‐chloro‐2‐oxo‐N‐[3‐(10H‐phenothiazin‐10‐yl)propyl]azetidine‐1‐carboxamides, 4a – 4m , is described. Phenothiazine on reaction with Cl(CH₂)₃Br at room temperature gave 10‐(3‐chloropropyl)‐10H‐phenothiazine ( 1 ), and the latter reacted with urea to yield 1‐[3‐(10H‐phenothiazin‐10‐yl)propyl]urea ( 2 ). Further reaction of 2 with several substituted aromatic aldehydes led to N‐(arylmethylidene)‐N′‐[3‐(phenothiazin‐10‐yl)propyl]ureas 3a – 3m , which, on treatment with ClCH₂COCl in the presence of Et₃N, furnished the desired racemic trans‐2‐oxoazetidin‐1‐carboxamide derivatives 4a – 4m . The structures of all new compounds were confirmed by IR, and ¹H‐ and ¹³C‐NMR spectroscopy, FAB mass spectrometry, and chemical methods.     

Cu(II)‐catalyzed oxidation of thiols by superoxide ligated to CoIII2

Copper(II) dramatically catalyzes the oxidation of thiols by a superoxide bridging two Co^III ions. The catalyzed path overwhelmingly dominates over the uncatalysed path and is first order in the superoxo complex concentration. The first‐order rate constants show a first‐order dependence in [Cu²⁺], a second‐order dependence in [thiol] and linearly varies with [H⁺]^?3. On the basis of observed kinetics reported here, it is proposed that Cu(II) reacts with two thiol molecules to form a Cu^II(thiol)₂ complex, an electron is transferred from one ligated thiol to the Cu^II center to form Cu^I(thiol) and a thiyl radical. The copper(I)‐thiol complex is oxidized by the conjugate base of the title complex to regenerate Cu^II(thiol). A Cu^II/I catalytic cycle is thus believed to be responsible for the observed catalysis. Copyright © 2012 John Wiley & Sons, Ltd.     

Synthesis and characterization of noscapine loaded magnetic polymeric nanoparticles

The delivery of noscapine therapies directly to the site of the tumor would ultimately allow higher concentrations of the drug to be delivered, and prolong circulation time in vivo to enhance the therapeutic outcome of this drug. Therefore, we sought to design magnetic based polymeric nanoparticles for the site directed delivery of noscapine to invasive tumors. We synthesized Fe₃O₄ nanoparticles with an average size of 10±2.5 nm. These Fe₃O₄ NPs were used to prepare noscapine loaded magnetic polymeric nanoparticles (NMNP) with an average size of 252±6.3 nm. Fourier transform infrared (FT-IR) spectroscopy showed the encapsulation of noscapine on the surface of the polymer matrix. The encapsulation of the Fe₃O₄ NPs on the surface of the polymer was confirmed by elemental analysis. We studied the drug loading efficiency of polylactide acid (PLLA) and poly (l-lactide acid-co-gylocolide) (PLGA) polymeric systems of various molecular weights. Our findings revealed that the molecular weight of the polymer plays a crucial role in the capacity of the drug loading on the polymer surface. Using a constant amount of polymer and Fe₃O₄ NPs, both PLLA and PLGA at lower molecule weights showed higher loading efficiencies for the drug on their surfaces.     

Sensing of Fe(III) ion via turn-on fluorescence by fluorescence probes derived from 1-naphthylamine

Fluorescence probes NA1 and NA2 derived from 1-naphthylamine (NA) as fluorophore have been synthesized and characterized by different spectroscopic studies. Identification behaviour of these probes towards various metal ions has been investigated. Both the fluorescent probes are selective as well as sensitive towards Fe(III) ion. Novel fluorescence probe NA2 afforded turn-on fluorescence behaviour for Fe(III) ion over other metal ions such as Ca(II), Mg(II), Mn(II), Fe(II), Co(II), Fe(III), Ni(II), Cu(II), Zn(II) and Hg(II).     

Modification of Electrode Surfaces by Self‐Assembled Monolayers of Thiol‐Terminated Oligo(Phenyleneethynylene)s

The wire‐like properties of four S‐(4‐{2‐[4‐(2‐phenylethynyl)phenyl]ethynyl}phenyl) thioacetate derivatives, PhC≡CC₆H₄C≡CC₆H₄SAc ( 1 ), H₂NC₆H₄C≡CC₆H₄C≡CC₆H₄SAc ( 2 ), PhC≡CC₆H₂(OMe)₂C≡CC₆H₄SAc ( 3 ) and AcSC₆H₄C≡CC₆H₄C≡CC₆H₄SAc ( 4 ) (Figure 1 ), all of which possess a high degree of conjugation along the oligo(phenyleneethynylene) (OPE) backbone, were investigated as self‐assembled monolayers (SAMs) on gold and platinum electrodes by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The redox probe [Fe(CN)₆]₄^? was used in both the CV and impedance experiments. The results indicate that the thiolates derived from thioacetate‐protected precursor molecules 1 and 2 form well‐ordered monolayers on a gold electrode, whereas SAMs derived from 3 and 4 exhibit randomly distributed pinholes. The electron tunnelling resistance and fractional coverage of SAMs of all four compounds were examined using electron tunnelling theory. The analysis of the results reveal that the well‐ordered SAMs of 1 and 2 exhibit higher charge‐transfer resistance in comparison to the defect‐ridden SAMs of 3 and 4 . The additional steric bulk offered by the methoxy groups in 3 is likely to prevent efficient packing within the SAM, leading to a microelectrode behaviour, when assembled on a gold electrode surface. The protected dithiol derivative 4 probably binds to the surface through both terminal groups which prevents dense packing and leads to the formation of a monolayer with randomly distributed pinholes. Atomic force microscopy (AFM) was used to examine the morphology of the monolayers, and height images gave root‐mean‐square (RMS) roughness′s which are in agreement with the proposed SAM structures.