Transition-metal- and organic-solvent-free: a highly efficient anaerobic process for selective oxidation of alcohols to aldehydes and ketones in water

A new system, I2-KI-K2CO3-H2O, selectively oxidized alcohols to aldehydes and ketones under anaerobic condition in water at 90 degrees C with excellent yields. The process is green, mild and inexpensive.     

Mode of Antibacterial Activity of Eclalbasaponin Isolated from Eclipta alba

The present study was undertaken to evaluate the mode of antibacterial activity of Eclalbasaponin isolated from Eclipta alba, against selected Gram-positive and Gram-negative bacteria. The probable chemical structure was determined by using various spectroscopic techniques such as Fourier transform infrared spectroscopy (FTIR) and mass spectroscopy. The antibacterial activity was evaluated by well diffusion technique, pH sensitivity, chemotaxis, and crystal violet assays. Eclalbasaponin showed clear zone of inhibition against both Bacillus subtilis and Pseudomonas aeruginosa and exhibited growth inhibition at the pH range of 5.5–9.0. The isolated saponin exhibited its positive chemoattractant property for both bacterial strains. Results of crystal violet assay and the presence of UV-sensitive materials in the cell-free supernatant confirmed the cellular damages caused by the treatment of Eclalbasaponin. The release of intracellular proteins due to the membrane damage was determined by sodium dodecyl sulfate polyacrylamide gel electrophoresis. Changes in the cell surface structure and membrane disruption were further revealed by FTIR and scanning electron microscopy analysis. The present study suggests that the isolated saponin from E. alba causes the disruption of the bacterial cell membrane which leads to the loss of bacterial cell viability.     

Rhodium(I) carbonyl complexes of chalcogen functionalized tripodal phosphines, [CH3C(CH2P(X)Ph2)3] {X = O, S, Se} and their reactivity

The reaction of dimeric rhodium precursor [Rh(CO)₂Cl]₂ with two molar equivalent of 1,1,1-tris(diphenylphosphinomethyl)ethane trichalcogenide ligands, [CH₃C(CH₂P(X)Ph₂)₃](L), where X = O(a), S(b) and Se(c) affords the complexes of the type [Rh(CO)₂Cl(L)] (1a–1c). The complexes 1a–1c have been characterized by elemental analyses, mass spectrometry, IR and NMR (¹H, ³¹P and ¹³C) spectroscopy and the ligands a–c are structurally determined by single crystal X-ray diffraction. 1a–1c undergo oxidative addition (OA) reactions with different electrophiles such as CH₃I, C₂H₅I and C₆H₅CH₂Cl to give Rh(III) complexes of the types [Rh(CO)(COR)ClXL] {R = –CH₃ (2a–2c), –C₂H₅ (3a–3c); X = I and R = –CH₂C₆H₅ (4a–4c); X = Cl}. Kinetic data for the reaction of a–c with CH₃I indicate a first-order reaction. The catalytic activity of 1a–1c for the carbonylation of methanol to acetic acid and its ester is evaluated and a higher turn over number (TON = 1564–1723) is obtained compared to that of the well-known commercial species [Rh(CO)₂I₂]⁻ (TON = 1000) under the reaction conditions: temperature 130 ± 2 °C, pressure 30 ± 2 bar and time 1 h.     

KF/Al2O3 mediated 1,3-dipolar cycloaddition of azomethine ylides: a novel and convenient procedure for the synthesis of highly substituted pyrrolidines

The regio- and diastereoselective synthesis of pyrrolidine derivatives through 1,3-dipolar cycloaddition of an azomethine ylide and dipolarophile mediated by KF/Al₂O₃, a versatile solid supported reagent, is reported. KF/Al₂O₃ is sufficiently basic such that it can deprotonate α-imino esters to generate azomethine ylides and it also functions as a solid supported catalyst leading to the cycloadduct rather than the Michael adduct.     

Enhancing the stability of colloidal silver nanoparticles using polyhydroxyalkanoates (PHA) from Bacillus circulans (MTCC 8167) isolated from crude oil contaminated soil

Polyhydroxyalkanoate (PHA) was produced by growing Bacillus circulans (MTCC 8167) in the specific detection medium. The identification of the polymer as PHA was confirmed by fluorescence microscopy. The PHA was purified and characterized using FT-IR. The silver nanoparticles (SNP) were synthesized from AgNO3 in the dispersed colloids of PHA (0.085%) using NaBH4 (sodium borohydrate as reducing agent). The stability was tested using wave length scanning with a UV-Vis spectrophotometer and finally with transmission electron microscopy. The PHA stabilized solution was found to be stable for 30 days as against the low stability of silver nanoparticles (SNP) solution alone.     

Benedict's solution/ vitamin C: An alternative catalytic protocol for the synthesis of regioselective‐1,4‐disubstituted‐1H‐1,2,3‐triazoles at room temperature

A novel and highly efficient method for the synthesis of 1,4‐disubstituted‐1H‐1,2,3‐triazoles by copper‐catalyzed azide‐alkyne cycloaddition has been developed. This economic and sustainable protocol uses a readily available Benedict's solution/Vitamin C catalyst system affording a wide range of 1,4‐disubstituted‐1H‐1,2,3‐triazoles under mild conditions.     

Investigation of antioxidant property of iron oxide particlesby 1′-1′diphenylpicryl-hydrazyle (DPPH) method

We investigated the antioxidant properties of iron oxide particles. Particles of different sizes were synthesized and their antioxidant potency was investigated by using an in vitro system. The antioxidant capacity assay was done via a modified DPPH method for insoluble solid materials. The percentages of DPPH scavenging were calculated for iron oxide particles. The particles were found to show antioxidant potency. The DPPH scavenging increases with decrease in particle size.     

AlCl(3) x 6H(2)O/KI/H(2)O/CH(3)CN: a new alternate system for dehydration of oximes and amides in hydrated media

Dehydration of oximes and amides to nitriles was carried out using the AlCl(3) x 6H(2)O/KI/H(2)O/CH(3)CN system. It produced isoquinoline derivatives 8a-c (Bischler Naperialski reaction) when reacted with amides 7a-c in hydrated media. Also, the keto oximes produced anilides (Beckmann rearrangement) with the system under the same reaction conditions.     

Neutral all metal aromatic half-sandwich complexes between alkaline earth and transition metals: an ab initio exploration

Structural Chemistry - Sandwich complexes find their interests among the chemists after the breakthrough discovery of ferrocene. Since then, a number of sandwich and half-sandwich complexes were...     

Pentacene thin film transistors using La2O3 as gate insulator

A study of Pentacene OTFTs using La₂O₃ as gate insulator is presented. The device characteristics were studied and analyzed. The OTFTs exhibit p-type conductivity with field effect mobility 6.5 × 10⁻⁸ m²/V.s, ON/OFF ratio 1.4 × 10², sub-threshold swing 2 mV/decade and hole concentration 4.5 × 10¹⁷ cm⁻³. The SEM and XRD analysis on the semiconductor film are also reported.