Synthesis of N‐Protected/Free Indole‐7‐Carboxaldehyde

A direct method for the preparation of N‐protected/free indole‐7‐carboxaldehyde is reported from the corresponding N‐protected 7‐bromomethylindoles using three different conditions.     

Synthesis and Characterization of Poly(Aryl Ether-Bissulfone)s

A series of poly(aryl ether-bissulfone)s were synthesized from bis-phenols, 4,4′-bis(4-chlorophenylsulfonyl)biphenyl, and 4,4′-bis(4-fluorophenylsulfonyl)biphenyl. The bishalide monomers were synthesized by reaction of 4,4′-bis(chlorosulfonyl)biphenyl with a suitable aryl halide. Potassium carbonate mediated reaction in di-methylacetamide gave high molecular weight polymers in excellent yield. The polymers are soluble in dipolar aprotic solvents. Unlike the corresponding monosulfone analogues, the poly(aryl ether-bissulfone)s exhibited poor solubility in chlorinated hydrocarbons. The glass transition temperatures of the polymers are among the highest known for poly(aryl ether)s (241-271 °C). In addition, the polymers exhibit excellent thermal stability and they produce clear, colorless tough films by solution casting or compression molding.     

Microwave-assisted chemoselective synthesis of novel pyrazolo[3,4-b]thieno[3,4-e]pyridines: substitution induced axial chirality

A microwave-assisted chemoselective synthesis of novel pyrazolo[3,4-b]thieno[3,4-e]pyridines has been achieved via tandem Michael addition–cyclization–tautomerization–oxidative aromatization sequence of reactions. Compounds with ortho-substituted phenyl rings exhibited axial chirality due to restricted rotation around C–C single bond.     

Low-valent vanadium complexes of a pyrrolide-based ligand. Electronic structure of a dimeric V(I) complex with a short and weak metal-metal bond

Deprotonation of the nitrogen atoms of the two pyrrole rings of 1,3-bis-{[(1'-pyrrol-2-yl)-1,1'-dimethyl]methyl}benzene with KH followed by further reaction with either VCl 3(THF) 3 or with VCl 2(TMEDA) 2 respectively gave the paramagnetic complexes [1,3-bis-{[(1'-pyrrol-2-yl)-1,1'-dimethyl]methyl}benzene]VCl(DME) ( 1) and [1,3-bis-{[(1'-pyrrol-2-yl)-1,1'-dimethyl]methyl}benzene]V(THF) 3 ( 2). Further reduction with the appropriate amount of KH afforded diamagnetic dinuclear [1,3-bis-{[(1'-pyrrol-2-yl)-1,1'-dimethyl]methyl}benzene]V} 2] ( 3). In complex 3, the bridging interaction between the two metal centers is realized via the ligand central benzene ring. Density functional theory calculations have elucidated the nature of the electronic interaction between the two metals with the bridging pi-system thus accounting for its visible structural distortion. Calculations also pointed out the presence of only a weak V-V bond in spite of the short V-V distance.     

A one pot synthesis of annulated carbazole analogs

A ZnBr₂-mediated arylation of N-protected 2/3-bromomethylindoles containing an electron-deficient malonylidene unit with arenes at 80 °C led to the formation of arylated products, which on unprecedented 1,5-sigmatropic rearrangement followed by electrocyclization and subsequent aromatization with loss of diethylmalonate furnished the corresponding annulated carbazoles in reasonable yields.     

Mott-Schottky Analysis and Impedance Spectroscopy of TiO2/6T and ZnO/6T devices

Schottky junctions have been realized by evaporating gold spots on top of sexithiophen (6T), which is deposited on TiO 2 or ZnO with e-beam and spray pyrolysis. Using Mott-Schottky analysis of 6T/TiO2 and 6T/ZnO devices acceptor densities of 4.5x10(16) and 3.7x10(16) cm(-3) are obtained, respectively. For 6T/TiO2 deposited with the e-beam evaporation a conductivity of 9x10(-8) S cm(-1) and a charge carrier mobility of 1.2x10(-5) cm2/V s is found. Impedance spectroscopy is used to model the sample response in detail in terms of resistances and capacitances. An equivalent circuit is derived from the impedance measurements. The high-frequency data are analyzed in terms of the space-charge capacitance. In these frequencies shallow acceptor states dominate the heterojunction time constant. The high-frequency RC time constant is 8 micros. Deep acceptor states are represented by a resistance and a CPE connected in series. The equivalent circuit is validated in the potential range (from -1.2 to 0.8 V) for 6T/ZnO obtained with spray pyrolysis.     

Design,synthesis and biological evaluation of 3-(2-aminooxazol-5-yl)-2<Emphasis Type="Italic">H</Emphasis>-chromen-2-one derivatives

Background

In view of wide range of biological activities of oxazole, a new series of oxazole analogues was synthesized and its chemical structures were confirmed by spectral data (Proton/Carbon-NMR, IR, MS etc.). The synthesized oxazole derivatives were screened for their antimicrobial and antiproliferative activities.

Results and discussion

The antimicrobial activity was performed against selected fungal and bacterial strains using tube dilution method. The antiproliferative potential was evaluated against human colorectal carcinoma (HCT116) and oestrogen- positive human breast carcinoma (MCF7) cancer cell lines using Sulforhodamine B assay and, results were compared to standard drugs, 5-fluorouracil and tamoxifen, respectively.

Conclusion

The performed antimicrobial activity indicated that compounds 3, 5, 6, 8 and 14 showed promising activity against selected microbial species. Antiproliferative screening found compound 14 to be the most potent compound against HCT116 (IC₅₀?=?71.8 µM), whereas Compound 6 was the most potent against MCF7 (IC₅₀?=?74.1 µM). Further, the molecular docking study has been carried to find out the interaction between active oxazole compounds with CDK8 (HCT116) and ER-α (MCF7) proteins indicated that compound 14 and 6 showed good dock score with better potency within the ATP binding pocket and may be used as a lead for rational drug designing of the anticancer molecule.

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Influence of microstructure and deformation behavior on toughening of reactively compatibilized polyamide 6 and poly(ethylene-co-butyl acrylate) blends

Influence of microstructure on impact toughness and fracture behavior of PA6 and EBA blends reactively compatibilized by EBA-g-MAH was quantitatively studied. The reactively compatibilized blends showed better distribution of elastomeric EBA particles in the PA6 matrix and the presence of EBA-g-MAH resulted in considerable reduction of interfacial tension between the component polymers. The interfacial adhesion between the PA6 and EBA phase in the compatibilized blends was enhanced by the interfacial reaction between the amide end-groups of PA6 and maleic anhydride group of EBA-g-MAH compared to uncompatibilized blends. The matrix ligament thickness and particle diameter values were lower than the predicted critical values and were responsible for the ductile behavior of the compatibilized blends. Stress whitening around the notch occurred in all the compatibilized blends which was the major energy dissipation zone in the blends. Matrix shear yielding or plastic flow without crazing was the dominant deformation mechanism in the tough compatibilized blends. There was no sign of shear yielding during impact fracture of the uncompatibilized blends where the elastomeric particles were completely dislodged from the matrix.