Cerium Catalyzed Michael Addition of 1,3-Dicarbonyl Compounds Under Microwave Irradiation

Cerium chloride heptahydrate proves to be an efficient catalyst for Michael addition of 1,3-dicarbonyl compounds, through a simple solvent free reaction under microwave irradiations.     

SOCl2/β-Cyclodextrin: A New and Efficient Catalytic System for Beckmann Rearrangement and Dehydration of Aldoximes Under Aqueous Condition

A rapid and efficient synthesis of amides via Beckmann rearrangement of ketoximes and dehydration of aldoximes to corresponding nitriles with good to excellent yields has been carried out in the presence of SOCl₂/β-cyclodextrin under aqueous conditions. The β-cyclodextrin has been recovered and reused.     

Room temperature synthesis of crystalline CeO2 nanopowder: advantage of sonochemical method over conventional method

In the present study, nano-sized ceria (CeO(2)) powders were prepared using conventional and sonochemically assisted precipitation method, without any stabilizers, using cerium nitrate as a starting material and sodium hydroxide as a precipitating agent. The synthesized ceria powders were characterized by XRD, TGA and SEM to determine crystallite size, % crystallinity, thermal weight loss and shape respectively. It was found that the crystallite size obtained in both the synthesis methods were below 30 nm. It was also found that sonochemical synthesis method is energy efficient method saving more than 92% of energy as compared to that utilized by the conventional synthesis method. There was also a significant reduction in the reaction duration.     

Two Photon Spectroscopy Can Serve as a Marker of Protein Denaturation Pathway

Rhodamine group of molecules are widely used dyes for imaging of biological molecules. Application of these dyes however includes a limitation that these molecules absorb in the visible range of the spectrum, which does not fall in the ‘biologically transparent window’ (BTW). Two photon absorption (TPA) process could come up with an alternate solution to this as these dyes could be excited in the near infrared (NIR) window to extract similar information. To validate this we have investigated TPA cross section (TPACS, σ₂) of two rhodamine dyes, namely Rhodamine 6G (R6G), Rhodamine B (RhB), site selectively bound with a model protein, bovine serum albumin (BSA), by exciting at 800 nm. Two photon spectroscopy and imaging confirms the binding of the dye to the protein. The decreases in TPACS with increasing temperature at a fixed BSA concentration excellently follows the temperature induced structural transition of BSA as the protein transforms from a molten globule to unfolded conformation beyond 60 °C, which has previously been established through circular dichroism (CD) measurements. The thus established resemblance in TPACS and CD measurement trends thus strongly affirms the suitability of TPA process in protein imaging and as an alternative marker to tracking its conformational transformations using NIR radiation.     

Zinc ionomer based on sulfonated maleated styrene-ethylene/butylene-styrene block copolymer

A new ionomer, containing both carboxylated and sufonated groups, was obtained by sulfonating a maleated styrene-ethylene/butylene-styrene (m-SEBS) block copolymer, followed by its neutralization with zinc acetate. Dielectric thermal analyses show that the incorporation of ionic groups in m-SEBS is responsible for the occurrence of the high temperature ionic relaxation in addition to the relaxations of the base polymer. Formation of the ionomer causes a significant improvement in stress-strain properties compared to the corresponding base polymer.