Thermoresponsive polymersome from a double hydrophilic block copolymer

The article describes synthesis and thermally triggered self‐assembly of a Poly (ethylene oxide)‐block‐poly (N‐insopropylacrylamide) (PEO‐b‐PNIPAm) in aqueous medium. At rt, the polymer remains as unimer, however, at lower critical solution temperature (LCST) of PNIPAm (32 °C), it forms a rather large undefined aggregate which at slightly elevated temperature (～40 °C) converges to well defined polymersome structure (Critical aggregation concentration = 0.45 mg/mL) with hydrodynamic diameter of 40–50 nm. By lowering the temperature, initial swelling of the compact vesicle followed by reversible disassembly to unimer was noticed. The polymersome exhibits encapsulation ability to a hydrophilic dye Calcein which can be spontaneously released by lowering the temperature below cloud point. Likewise a hydrophobic dye namely 8‐Anilino‐1‐naphthalenesulfonic acid (ANS) can also be encapsulated and released by thermal trigger. Detail photoluminescence studies reveal ANS dye can be used as a generalized probe molecule for detecting LCST of a thermoresponsive polymer by “fluorescence on” above LCST even by cursory observation. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2015 , 53, 2444–2451     

Garratt–Braverman cyclization on basic alumina: a green protocol with improved selectivity

A green protocol (compared to the existing methodology) for carrying out Garratt–Braverman cyclization has been developed. The method involves stirring a pre-absorbed bispropargyl sulfone/ether/sulfonamide over basic alumina. The reaction with sulfones was over within 10–15 min at room temperature whereas for the ether/sulfonamide the reaction took 6–8 h at 130 °C. The products, aryl naphthalene derivatives, are obtained by simple filtration through Celite, in excellent yields.     

Selective Benzylic CH-Borylations by Tandem Cobalt Catalysis

Metal-catalyzed C?H activations are environmentally and economically attractive synthetic strategies for the construction of functional molecules as they obviate the need for pre-functionalized substrates and minimize waste generation. Great challenges reside in the control of selectivities, the utilization of unbiased hydrocarbons, and the operation of atom-economical dehydrocoupling mechanisms. An especially mild borylation of benzylic CH bonds was developed with the ligand-free pre-catalyst Co[N(SiMe₃)₂]₂ and the bench-stable and inexpensive borylation reagent B₂pin₂ that produces H₂ as the only by-product. A full set of kinetic, spectroscopic, and preparative mechanistic studies are indicative of a tandem catalysis mechanism of CH-borylation and dehydrocoupling via molecular Co^I catalysts.     

Antioxidative and anticarcinogenic activities of methylpheophorbide a,isolated from wheat grass (Triticum aestivum Linn.)

Methylphophorbide a (MPa) has been isolated from the ethanol extract of the wheat grass plant. Its antioxidative efficacy is evaluated by hydroxyl radical scavenging activities and reducing capacity which are significantly up regulated in comparison with aqueous extract of the plant. The compound shows iron-binding capacity where the Fe²⁺ binds with MPa by two types of binding patterns with dissociation constants 157.17 and 27.89. It has antioxidative and cytotoxic effects on HeLa and Hep G2 cells. The cancerous cell survivability decreases with increasing concentration of MPa. These findings have provided evidence for the traditional use of the wheat grass plant in the treatment of cancers, oxidative stress and iron overloaded disorders.     

Densitometric HPTLC Analysis of Juglone,Quercetin, Myricetin,Rutin, Caffeic Acid,and Gallic Acid in Juglans regia L.

JPC – Journal of Planar Chromatography – Modern TLC - Asensitive, selective, and precise high-performance thin-layer chromatography (HPTLC) method was developed for simultaneous...     

Number Rigidity in Superhomogeneous Random Point Fields

Journal of Statistical Physics - We give sufficient conditions for the number rigidity of a large class of point processes in dimension $$d=1$$ and 2, based on the decay of correlations. Number...