Bis-spirochromanones as potent inhibitors of Mycobacterium tuberculosis: synthesis and biological evaluation

Molecular Diversity - On the basis of reported antimycobacterial property of chroman-4-one pharmacophore, a series of chemically modified bis-spirochromanones were synthesized starting from...     

Galactose Grafted Two-Dimensional Nanosheets as a Scaffold for the In Situ Synthesis of Silver Nanoparticles: A Potential Catalyst for the Reduction of Nitroaromatics

Two major hurdles in NP-based catalysis are the aggregation of the NPs and their recycling. Immobilization of NPs onto a 2D support is the most promising strategy to overcome these difficulties. Herein, amphiphilicity-driven self-assembly of galactose-hexaphenylbenzene-based amphiphiles into galactose-decorated 2D nanosheet is reported. The extremely dense decoration of reducing sugar on the surface of the sheets is used for the in situ synthesis and immobilization of ultrafine catalytically active AgNPs by using Tollens’ reaction. The potential of the system as a catalyst for the reduction of various nitroaromatics is demonstrated. Enhanced catalytic activity is observed for the immobilized AgNPs when compared to the corresponding discrete AgNPs. Recovery of the catalytic system from the reaction mixture by ultrafiltration and its subsequent recycling for several cycles without dropping its activity is shown. This is the first report demonstrating the in situ synthesis and immobilization of ultrafine AgNPs onto a 2D nanosheet that exhibits excellent catalytic performance for the reduction of nitroaromatics.     

Temperature dependence of NO2 sensitivity of YSZ-based mixed potential type sensor attached with NiO sensing electrode

A mixed potential type yttria-stabilized zirconia-based sensor using NiO sensing electrode and Pt reference electrode was fabricated, and its NO₂ sensing characteristics were examined at various operating temperatures in the range of 700–950 °C. It was observed that the sensitivity to NO₂ strongly depends on the operating temperature of the sensor; the sensitivity decreases with increasing operating temperature, while the response/recovery rates increase. To rationalize this temperature dependence of NO₂ response, polarization curves and complex impedances of the sensor were measured in the base gas and in the sample gas (400 ppm NO₂?+?base gas) at various operating temperatures. It turned out that the operating temperature had a strong influence on the rate of anodic reaction of oxygen; the increased rate of anodic reaction leads to lower NO₂ sensitivity and quicker response/recovery at higher operating temperature.     

Convenient Synthesis of α,α1 - bis (Substituted Furfurylidene) Cycloalkanones and Chalcones Under Microwave Irradiation.

Condensation of furfural with cycloalkanones and substituted acetophenones catalyzed by solid NaOH results in α, α¹-bis (substituted furfurylidene) cycloalkanones and chalcones in high yield under microwave irradiation for a duration of 2 minutes.     

Subshell Resolved Measurements of Single Electron Capture in Slow Ne7+–Helium Collisions

Hyperfine Interactions - We have performed drying-humectation cyclical processes (CEBELCOR) on eight A36 low carbon steel coupons in NaCl solutions containing 1×10?2 M and...     

Isomerization of N-[α-(Alkylthio)alkyl]- and N-[α-(Arylthio)alkyl]benzotriazoles

The thermal isomerizations of N-[α-(alkylthio)alkyl]- and N-[α-(arylthio)alkyl]benzotriazoles have been investigated under N₂ atmospheres (i) in toluene, xylene, MeOH, or EtOH, in the presence of acid catalysts and (ii) in the absence of solvent. The sulfide isomerization rates depend on the number of H-atoms carried by the C-atom attached to the N-atom of the benzotriazole: tertiary (no hydrogen) > secondary (1 hydrogen) > primary (2 hydrogens). The results support an isomenzation mechanism involving a heterolytic N? C bond cleavage with formation of sulfonium/carbonium and benzotriazolate ions.     

A mild,efficient and improved protocol for the friedländer synthesis of quinolines using lewis acidic ionic liquid

Lewis acidic ionic liquid is shown to be for the first time an excellent medium and efficient catalyst for the synthesis of quinolines at room temperature from o‐amino aromatic carbonyls and ketones containing active methylene group.     

Asymmetric methallylboration of prochiral aldehydes with methallyldiisopinocampheylborane·synthesis of 2-methyl-1-alken-4-ols in ≥ 90% enantiomeric purities

Methallyldiisopinocampheylborane, on condensation with aldehydes, provides 2-methyl-1-alken-4-ols in ≥ 90% enantiomeric purities.     

Experimental and theoretical comparison of actinide and lanthanide bonding in M[N(EPR(2))(2)](3) complexes (M = U, Pu, La, Ce; E = S, Se, Te; R = Ph, iPr, H)

Treatment of M[N(SiMe3)2]3 (M = U, Pu (An); La, Ce (Ln)) with NH(EPPh2)2 and NH(EPiPr2)2 (E = S, Se), afforded the neutral complexes M[N(EPR2)2]3 (R = Ph, iPr). Tellurium donor complexes were synthesized by treatment of MI3(sol)4 (M = U, Pu; sol = py and M = La, Ce; sol = thf) with Na(tmeda)[N(TePiPr2)2]. The complexes have been structurally and spectroscopically characterized with concomitant computational modeling through density functional theory (DFT) calculations. The An-E bond lengths are shorter than the Ln-E bond lengths for metal ions of similar ionic radii, consistent with an increase in covalent interactions in the actinide bonding relative to the lanthanide bonding. In addition, the magnitude of the differences in the bonding is slightly greater with increasing softness of the chalcogen donor atom. The DFT calculations for the model systems correlate well with experimentally determined metrical parameters. They indicate that the enhanced covalency in the M-E bond as group 16 is descended arises mostly from increased metal d-orbital participation. Conversely, an increase in f-orbital participation is responsible for the enhancement of covalency in An-E bonds compared to Ln-E bonds. The fundamental and practical importance of such studies of the role of the valence d and f orbitals in the bonding of the f elements is emphasized.