Cobalt-Catalyzed, 2-Aminopyridine-N-Oxide-Directed C(sp2)−H Bond Functionalization with Maleimides: Facile Access to Isoindolone Spirosuccinimides

A cobalt-catalyzed, N,O-bidentate directing group-assisted C−H bond functionalization of benzamides with maleimides was developed for the facile access to isoindolone spirosuccinimides in good to excellent yields. This C−H bond activation and spirocyclization employing pyridine N-oxide as directing group provided very good substrate scope and tolerated various functional groups. Furthermore, the mechanistic investigation revealed that the C−H bond activation is the rate-determining step of this reaction.     

Chemopreventive action of xanthone derivatives on photosensitized DNA damage

Photosensitized DNA damage participates in solar-UV carcinogenesis, photogenotoxicity and phototoxicity. A chemoprevention of photosensitized DNA damage is one of the most important methods for the above phototoxic effects. In this study, the chemopreventive action of xanthone (XAN) derivatives (bellidifolin [BEL], gentiacaulein [GEN], norswertianin [NOR] and swerchirin [SWE]) on DNA damage photosensitized by riboflavin was demonstrated using [32P]-5'-end-labeled DNA fragments obtained from genes relevant to human cancer. GEN and NOR effectively inhibited the formation of piperidine-labile products at consecutive G residues by photoexcited riboflavin, whereas BEL and SWE did not show significant inhibition of DNA damage. The four XAN derivatives decrease the formation of 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-oxodGuo), an oxidative product of G, by photoexcited riboflavin. The preventive action for the 8-oxodGuo formation of these XAN derivatives increased in the following order: GEN>NOR>BEL>SWE. A fluorescence spectroscopic study and ab initio molecular orbital calculations suggested that the prevention of DNA photodamage is because of the quenching of the triplet excited state of riboflavin by XAN derivatives through electron transfer. This chemoprevention is based on neither antioxidation nor a physical sunscreen effect; rather, it is based on the quenching of a photosensitizer. In conclusion, XAN derivatives, especially GEN, may act as novel chemopreventive agents by the quenching mechanism of an excited photosensitizer.     

An Efficient,One-Pot Synthesis of Carbamates from the Corresponding Alcohols Using <Emphasis Type="Italic">Mitsunobu</Emphasis>’s Reagent

Summary. A novel Mitsunobu-based protocol was developed for the synthesis of carbamates from the corresponding alcohols using carbon dioxide and amines in good to excellent yields. This protocol is mild, chemoselective, and efficient compared to other reported methods.     

A pyrene-benzthiazolium conjugate portraying aggregation induced emission,a ratiometric detection and live cell visualization of HSO3

The present study deals with the photophysical property of a pyrene-benzthiazolium conjugate R1, as a strong intramolecular charge transfer (ICT) probe exhibiting long wavelength emission in the red region. Unlike traditional planar polyaromatic hydrocarbons whose aggregation generally quenches the light emission, the pyrene based R1 was found to display aggregation-induced emission (AIE) property along with simultaneous increase in its quantum yield upon increasing the water content of the medium. The R1 exhibits high specificity towards HSO₃⁻/SO₃²⁻ by interrupting its own ICT producing there upon a large ratiometric blue shift of ∼220 nm in its emission spectrum. The lowest detection limit for the above measurement was found to be 8.90 × 10⁻⁸ M. The fluorescent detection of HSO₃⁻ was also demonstrated excellently by test paper strip and silica coated TLC plate incorporating R1. The live cell imaging of HSO₃^─ through R1 in HeLa cells was studied using fluorescence microscopic studies. The particle size and morphological features of R1 and R1-HSO₃⁻ aggregates in aqueous solution were characterized by DLS along with SEM analysis.     

Design and characterization of a modified WDM ring network – An analytical approach

The present paper proposes the design of a modified ring network topology with a significant improvement in average delay and blocking probability over the simple ring network. The backbone ring network is modified by connecting the alternate nodes in regions identified statistically as of high traffic density. A mathematical model for the proposed modified network has been developed to investigate the blocking probability and average delay as the data traverses from source to destination. The analysis reports an improvement in the average delay performance with the inception of call priority at the processing node and thus provides a scope to implement the given grade of service.     

Potential profile near the virtual cathode in presence of charged dust

In this work, concept of virtual cathode and its existence in dusty plasma has been studied by theoretical and numerical analysis. Using basic equations of charge dust, ions, and electrons, the non‐monotonic behaviour of the potential in presence of charged dust has been calculated and plotted as a function of dust density. It has been found that there is a change in potential between cathode and sheath potential and subsequently changes the threshold wall temperature as compared to that of without dust conditions. The threshold wall temperature has been increased due to the ability of micro‐particles acquiring electron charge and hence, reducing potential at the wall. Further, for different values of α (depends on dust density); threshold temperature remained the same for observed virtual cathode. Hence, behaviour of potential has been plotted as a function of α with increasing wall temperatures for two dust charge values (1 and 1,000). Considering no dust charge, it has been observed that, at lower dust density, double layer like structure is formed near the emissive wall. But this double layer structure gets diminishes with increasing dust density. Hence, below a threshold dust density, virtual cathode near to the emissive wall is not possible. While for Z_d = 1,000, the formation of virtual cathode appeared even at very small dust density. However, irrespective of variation of potential difference near the wall and existence of virtual cathode at different emission regime the threshold wall temperature remains same. Effect of dust potential dependency on threshold wall temperature has also been discussed in this study.     

Characterization of Fatty Acids,Polysaccharides, Amino Acids,and Minerals in Marine Macroalga Chaetomorpha crassa and Evaluation of Their Potentials in Skin Cosmetics

Cosmetic industries are highly committed to finding natural sources of functional active constituents preferable to safer materials to meet consumers’ demands. Marine macroalgae have diversified bioactive constituents and possess potential benefits in beauty care products. Hence, the present study was carried out to characterize the biochemical profile of marine macroalga Chaetomorpha crassa by using different techniques for revealing its cosmetic potentials. In results, the FTIR study characterized the presence of different bioactive functional groups that are responsible for many skin-beneficial compounds whereas six and fifteen different important phycocompounds were found in GCMS analysis of ethanolic and methanolic extracts, respectively. In the saccharide profile of C. crassa, a total of eight different carbohydrate derivatives were determined by the HRLCMS Q-TOF technique, which showed wide varieties of cosmetic interest. In ICP AES analysis, Si was found to be highest whereas Cu was found to be lowest among other elements. A total of twenty-one amino acids were measured by the HRLCMS-QTOF technique, which revealed the highest amount of the amino acid, Aspartic acid (1207.45 nmol/mL) and tyrosine (106.77 nmol/mL) was found to be the lowest in amount among other amino acids. Their cosmetic potentials have been studied based on previous research studies. The incorporation of seaweed-based bioactive components in cosmetics has been extensively growing due to its skin health-promoting effects.     

One-Pot Multicomponent Synthesis,Molecular Docking,and In Vitro Antibacterial Activities of 1-{(Aryl)[(5-methyl-1,3-thiazol-2-yl)amino]methyl}naphthalen-2-ol

Russian Journal of Organic Chemistry - A series of new Betti bases, 1-{(aryl)[(5-methyl-1,3-thiazol-2-yl)amino]methyl}naphthalen-2-ols, have been synthesized via one-pot three-component reaction of...