New iridoid glucoside from Wendlandia tinctoria roots

A new iridoid glucoside,10-O-veratroyleranthemoside(1) was isolated from the roots of Wendlandia tinctoria.The structure was established by spectroscopic(including 2D NMR) and chemical methods.     

Sterically driven electronic properties of naphthalene- and anthracene-end-capped 2,2′-bipyridine luminophores: synthesis and density functional theory

Two naphthalene- and one anthracene-end-capped 4,4′-π-conjugated-2,2′-bipyridine chromophores have been synthesized via the Horner-Wordsworth-Emmons reaction protocol and their electronic absorption and emission properties have been examined. DFT and TD-DFT computational studies have been carried out in order to comprehend the role of steric factor over the electronic factor.     

Kinetics of proton transfer between ortho substituted benzoic acids and the carbinol base of crystal violet in toluene. Ortho effect on the reactivity of benzoic acids in apolar aprotic solvents

Apolar aprotic solvents are particularly advantageous for investigating the intrinsic ortho effect free from complications of specific solvent effects. A kinetic study for toluene-phase proton transfers between ortho F, Cl, Br, I, OMe, OEt, OPh, OAc, Me, NO(2), COMe, COPh, OH, NH(2), and H benzoic acids and crystal violet carbinol base has shown the forward rate constant (log k(+1)) is the most appropriate reactivity parameter in toluene. log k(+1) (toluene) as compared to other reported reactivity parameters in benzene, toluene, or chlorobenzene has been found more sensitive to the ortho substituent effect. The regression results of the correlation of log k(+1) (toluene) of the acids (except OH and NH(2) substituted ones) according to seven ortho effect models are all very significant, and the best result is given by Fujita-Nishioka's model. The overall analysis reveals that a substituent's ortho effect pattern is a 58:24:18 ratio of its ordinary electrical, proximity electrical, and steric effects and that the proximity electrical effect is the major component to account for the peculiarity of the substituent's ortho effect. The results further favor the transmission of this effect mainly through the molecular cavity. The effect may, however, be outweighed by the steric component for bulky enough substituents, e.g., Me. The enhanced strength exhibited by salicylic acid in toluene has been quantitatively described using Pytela-Lis?ka's σ(HB)(i) parameter. The abnormally high log k(+1) observed for anthranilic acid in toluene has been ascribed to a very extensive homoconjugation in its acid-acid anion complex induced by the acid's three hydrogen bond donors.     

Synthesis,characterization, and properties of semifluorinated organo‐soluble new aromatic polyamides

A series of organo‐soluble new polyamides were synthesized by the direct polycondensation of different semifluorinated aromatic diamines, namely 4,4‐bis[3'‐trifluoromethyl‐4'(4“‐amino benzoxy)benzyl]biphenyl; 4,4”‐bis(aminophenoxy)‐3'3“‐trifluoromethyl terphenyl; 1,3‐bis[3'‐trifluoromethyl‐4'(4”‐amino benzoxy)benzyl]benzene; 2,6‐bis(3'‐trifluoromethyl‐p‐aminobiphenyl ether)pyridine; and 2,5‐bis(3'‐trifluoromethyl‐p‐aminobiphenyl ether)thiophene with 5‐t‐butyl‐isophthalic acid. The polymers were fully characterized by elemental analysis and IR, NMR spectroscopies. The synthesized polyamides were soluble in several organic solvents such as 1‐methyl‐2‐pyrrolidone, N,N‐dimethylformamide, N,N‐dimethylacetamide, tetrahydrofuran, and dimethyl sulfoxide at room temperature. They showed inherent viscosities of 0.42–0.63 dl/g. The polyamides exhibited weight‐average molecular weights of up to 233,000, which depended on the exact repeating unit structure. The polyamides synthesized from 4,4‐bis[3'‐trifluoromethyl‐4'(4”‐amino benzoxy)benzyl]biphenyl and 5‐t‐butyl isophthalic acid exhibited highest glass‐transition temperatures 261°C (evaluated by differential scanning calorimetry) in nitrogen. These polyamides showed good thermal stability up to 475°C for a 10% weight loss in air. The polyamides films were clear and flexible in nature with tensile strengths of up to 88 MPa, modulus of elasticity of up to 1.81 GPa, and elongations at break of up to 25%, which depended on the exact repeating unit structure. X‐ray diffraction measurements indicated that these polyamides were amorphous in nature. Copyright © 2010 John Wiley & Sons, Ltd.     

Estimation of radiological indices in Indian Sundarbans: a mangrove habitat

Stereoscopic porous microspheres based gellan gum (GG–Ca) were successfully prepared by sol–gel method using ethyl acetate as porogen and glutaraldehyde as crosslinker. The obtained GG–Ca microspheres were mainly of mesoporous with the average pore diameter was about 4 nm. It displayed a higher ability for uranium removal. In addition, the uranium adsorption process was endothermic and spontaneous following a pseudo-second-order and the adsorption isotherm was the best fit with the Freundlich model with maximum uranium capacity of 202.26 mg g⁻¹. The UO²⁺ adsorption mechanism is ion-exchange with Ca²⁺ based on SEM, EDX and XPS data analysis.

     

Quantitative estimation of total potassium and 40K in surface soil samples of Indian Sundarbans

The present study attempts to quantitatively estimate total potassium content in soil samples collected from different areas of Indian Sundarbans by gamma-spectrometry, exploiting the radiogenic properties of potassium and by wavelength dispersive X-ray fluorescence technique. The elemental K concentration varied in between 2.08 ± 0.05 and 3.46 ± 0.06% in the soil samples. Besides estimation of total potassium, the activity of ⁴⁰K was also estimated in the same soil samples and found to be in the range of 532 ± 8.9 to 1043 ± 13.2 Bq kg⁻¹.

     

Oxidative Coupling of Benzylamines with Indoles in Aqueous Medium to Realize Bis‐(Indolyl)Methanes Using a Water‐Soluble Cobalt Catalyst and Air as the Oxidant

Oxidative coupling of benzylamines with indoles to bis‐(indolyl)methanes (BIMs) was achieved using an inexpensive water‐soluble cobalt complex, Co(bpb). The catalyst was found to be quite effective when air was used as the oxidant and water as solvent under mild reaction conditions. Aromatic amines were successfully converted to the corresponding BIMs with yields up to 85 %. We have successfully carried out a 1 gram scale reaction, and few pharmaceutically relevant compounds were also synthesised by this method in good yields. Control experiments have also been carried out to understand the possible reaction mechanism.     

Proton‐Conducting Hydrogen‐Bonded 3D Frameworks of Imidazo‐Pyridine‐Based Coordination Complexes Containing Naphthalene Disulfonates in Rhomboid Channels

Coordination complexes of an olefinic molecule (PIP) containing pyridine and imidazopyridine moieties with Zn^II/Ni^II metal salts were shown to exhibit appreciable proton conductivity. These complexes form 3D‐hydrogen bonded frameworks containing rhomboidal channels that are occupied by uncoordinated 1,5‐naphthalenedisulfonate (NDS). The extensive hydrogen bonding between the frameworks and NDS resulted in thermally stable and water‐insoluble materials. Irrespective of the metal atom present, both complexes exhibited moderate to high proton conduction in the range of 10^?5 to 0.5×10^?3 S cm^?1 depending on the temperature and humidity levels.