Single layer graphene: an alternative electrode material for ferroelectric liquid crystal based displays

We made comparative investigations on indium tin oxide (ITO) and single-layer graphene (SLG)-coated glass substrate as electrodes, specially for ferroelectric liquid crystal (FLC)-based system. We experimentally examined the comparative behaviour of important electro-optical FLC parameters for ITO- and SLG-based sample cells. The parameters are observed to be almost similar for both the cells. Interestingly, the value of threshold voltage is observed lower in SLG-based cell in comparison to that of conventional ITO/ITO cell. The presented results will definitely add a step to prove the suitability of graphene to be used as transparent electrodes in FLC-based display devices.     

Copper diisobutyl-t-butoxyaluminum hydride: A novel reagent for chemoselective reduction of tertiary amides over esters

We demonstrate that copper diisobutyl-t-butoxyaluminum hydride, readily prepared from lithium diisobutyl-t-butoxyaluminum hydride and CuI, effectively and chemoselectively reduces tertiary amides over esters at ambient temperature, affording the corresponding aldehydes in excellent yields.     

Site-selective C–H nitration of N-aryl-7-azaindoles under palladium(II) catalysis

The site-selective C–H nitration reaction of 7-azaindoles with t-butyl nitrite under palladium catalysis is described. This protocol provides an efficient method for the construction of ortho-nitrated N-aryl-7-azaindoles with excellent site-selectivity and functional group compatibility. The formed 7-azaindole derivatives can be readily transformed into 7-azaindoles containing an aniline functional group under palladium-catalyzed hydrogenation conditions.     

Transition metal mediated selective C vs N arylation of 2-aminonaphthoquinone and its application toward the synthesis of benzocarbazoledione

Selective C vs N-arylation of 2-aminonaphthoquinone was achieved using different transition metal salts and arylboronic acids. Mn(OAc)₃·2H₂O provided C-arylated product whereas NiCl₂·6H₂O and Cu(OAc)₂·H₂O provided N-mono arylated and N,N-diarylated products respectively. Usefulness of the C and N arylated product was demonstrated by converting it into benzocarbazoledione.     

Hydro­gen bonding in two tetracyclic indole alkaloids

3-Acetyl-1,6,7,12b-tetra­hydro­indolo­[2,3-a]­quinolizin-2(12H)-one, C₁₇H₁₆N₂O₂, consists of two symmetry-independent mol­ecules and each forms a layered structure stabilized by N—H⃛O and C—H⃛O hydrogen bonds. In 3-acetyl-6,7-di­hydro­indolo­[2,3-a]­quinolizin-4(12H)-one monohydrate, C₁₇H₁₄N₂O₂·H₂O, the structure is stabilized by O—H⃛O, N—H⃛O and C—H⃛O hydrogen bonds, with the ordered water mol­ecule playing a crucial role in the self-assembly. Contribution from the weak interactions to the strong hydrogen-bonded network is a common feature in both structures.     

Synthesis and characterization of polyesters containing heterocyclic thiaxanthone units

Several polyesters containing thiaxanthone rings were prepared from 2,7-dichloroformylthiaxanthone-5,5′-dioxide ( IVa ), 2,8-dichloroformylthiaxanthone-5,5′-dioxide ( IVb ), and bisphenols by solution polycondensation. The 2,8-diethoxycarbonylthiaxanthone-5,5′-dioxide ( V ) was prepared and characterized by spectral methods to confirm the formation of 2,8-thiaxanthonedicarboxylic acid-5,5′-dioxide ( IVb ). Prior to polymer synthesis two model compounds,2,7-diphenoxycarbonylthiaxanthone-5,5′-dioxide (MDE-1) and 2,8-diphenoxycarbonylthiaxanthone-5,5′-dioxide (MDE-2), were synthesized and characterized by spectral methods. The polyesters were obtained in 62–78% yield and had inherent viscosities in the range 0.42–0.90 dL/g. The effect of thiaxanthone rings on solubility, crystallinity, and thermal stability of the polyesters are also discussed. The polyesters have decomposition temperatures in the range 372–438°C.     

Molecular beacons: a real-time polymerase chain reaction assay for detecting Escherichia coli from fresh produce and water

Molecular beacons (MBs) are oligonucleotide probes that fluoresce upon hybridization. The development of a real-time polymerase chain reaction (PCR) assay to detect the presence of Escherichia coli using these fluorogenic reporter molecules is reported. MBs were designed to recognize a 19-bp region of the uid A gene, coding for an enzyme β-glucuronidase. The specificity of the MB-based PCR assay was evaluated for various E. coli strains as well as bacteria species that are present in nature. The capability of the assay to detect E. coli in drinking water and produce was demonstrated. Positive detection of E. coli was demonstrated when >10¹ CFU mL⁻¹ (colony forming unit) was present in the water samples and fresh produce after 18 h of enrichment. These assays could be carried out entirely in sealed PCR tubes, enabling rapid and semiautomated detection of E. coli in food and environmental samples.     

Microwave-Assisted Synthesis and Antimicrobial Activity of 3-(Arylsulfanyl)-4-hydroxy-2<Emphasis Type="Italic">H</Emphasis>-chromen-2-ones

An efficient microwave-assisted synthesis of 3-(arylsulfanyl)-4-hydroxy-2H-chromen-2-ones by condensation of arenesulfonohydrazides with 4-hydroxy-2H-chromen-2-one in the presence of iodine is described. The synthesized compounds were characterized by spectral data (IR, ¹H and ¹³C NMR, and mass spectra and elemental analyses) and were tested for their in vitro antimicrobial activity against bacterial and fungal organisms.     

Mechanism of iridium(III) catalysis in the oxidation of diols by N-bromoacetamide

Summary The kinetics of iridium(III)-catalysed oxidation of 1,2-ethanediol and 1,4-butanediol by N-bromoacetamide (NBA) in HClO₄ in the presence of [Hg(OAc)₂] as a scavenger for Br^– have been investigated. The reactions are zero-order with respect to both diols, and first-order in NBA at low NBA concentrations, tending to zero order at high concentrations. The order in Ir^III decreases from unity to zero at high iridium(III) concentrations. A positive effect on the oxidation rate is observed for [H⁺] and [Hg^II] whereas a negative effect is observed for acetamide and [Cl^–]. Ionic strength does not influence the oxidation rate. (H₂OBr)⁺ is postulated as the oxidizing species. A mechanism consistent with the observed kinetic data is proposed.