Environmentally benign approach towards C–S cross-coupling reaction by organo-copper(II) complex

Molecular Diversity - C–S cross-coupling reaction in water giving an excellent yield of the desired C–S coupled product by using a newly developed...     

Synthesis of 5-alkynylated uracil-morpholino monomers using Sonogashira coupling

Sonogashira coupling of 5-iodo uracil-morpholino monomer with different terminal alkynes has been achieved for first time in good to excellent yields (67-86%). We have optimized the iodination conditions for the preparation of 5-iodo uracil-morpholino monomer under basic condition.     

Selective Sensing of Phosphates by a New Bis‐heteroleptic RuII Complex through Halogen Bonding: A Superior Sensor over Its Hydrogen‐Bonding Analogue

The selective phosphate‐sensing property of a bis‐heteroleptic Ru^II complex, 1 [PF₆]₂, which has a halogen‐bonding iodotriazole unit, is demonstrated and is shown to be superior to its hydrogen‐bonding analogue, 2 [PF₆]₂. Complex 1 [PF₆]₂, exploiting halogen‐bonding interactions, shows enhanced phosphate recognition in both acetonitrile and aqueous acetonitrile compared with its hydrogen‐bonding analogue, owing to considerable amplification of the Ru^II‐center‐based metal‐to‐ligand charge transfer (MLCT) emission response and luminescence lifetime. Detailed solution‐state studies reveal a higher association constant, lower limit of detection, and greater change in lifetime for complex 1 in the presence of phosphates compared with its hydrogen‐bonding analogue, complex 2 . The ¹H NMR titration study with H₂PO₄^? ascertains that the binding of H₂PO₄^? occurs exclusively through halogen‐bonding or hydrogen‐bonding interactions in complexes 1 [PF₆]₂ and 2 [PF₆]₂, respectively. Importantly, the single‐crystal X‐ray structure confirms the first ever report on metal‐assisted second‐sphere recognition of H₂PO₄^? and H₂P₂O₇^2? with 1 through a solitary C?I???anion halogen‐bonding interaction.     

Detection of Free Thiols and Fluorescence Response of Phycoerythrin Chromophore after Ultraviolet-B Radiation Stress

The chemistry of thiol-chromophore linkage plays a central role in the nature of fluorescence of phycoerythrin (PE). Interaction of thiol and chromophore is crucial for the energy transfer, redox signal and inhibition of oxidative damage. In the present investigation the effects of ultraviolet-B radiation on an emission fluorescence intensity and wavelength shift in PE due to interaction between thiol and chromophore by remarkable strategy of detection technique was studied. Purification of PE was done by using a gel permeation and ion exchange chromatography that yielded a quite high purity index (6.40) in a monomeric (αβ) form. UV-B radiation accelerated the quenching efficiency (24.9 ± 1.52%) by reducing fluorescence emission intensity of thiol linked chromophore after 240 min of UV-B exposure. However, after blocking of transiently released free thiol by N-ethylmaleimide, quenching efficiency was increased (36.8 ± 2.80%) with marked emission wavelength shift towards shorter wavelengths up to 562 nm as compared to 575 nm in control. Emission fluorescence of free thiol was at maximum after 240 min that was detected specifically by monobromobimane (mBrB) molecular probe. The association/dissociation of bilin chromophore was analyzed by SDS- and Native-PAGE that also indicated a complete reduction in emission fluorescence. Our work clearly shows an early detection of free thiols and relative interaction with chromophore after UV-B radiation which might play a significant role in structural and functional integrity of terminal PE.     

MnFe2O4 Nanocrystals Wrapped in a Porous Organic Polymer: A Designed Architecture for Water‐Splitting Photocatalysis

A novel MnFe₂O₄–porous organic polymer (POP) nanocomposite was synthesized by a facile hydrothermal method and using the highly cross‐linked N‐rich benzene–benzylamine POP. The nanocomposite presented highly efficient photocatalytic performance in the hydrogen evolution reaction (HER) from pure water without addition of any sacrificial agent under one AM 1.5 G sunlight illumination. A photocatalytic activity of 6.12 mmol h^?1 g^?1 was achieved in the absence of any noble metal cocatalyst, which is the highest H₂ production rate reported for nonprecious metal catalysts. The photocatalytic performance of MnFe₂O₄‐POP could be attributed to the intrinsic synergistic effects of manganese ferrite (MnFe₂O₄) nanoclusters interacting with the nitrogen dopant POP with a unique mesoporous nanoarchitecture and spatially confined growth of MnFe₂O₄ in the interconnected POP network, leading to high visible‐light absorption with fast electron transport.     

Structural and proton conductivity study of BaZr1-xRExO3-δ(RE = Dy,Sm) ceramics for intermediate temperature solid oxide fuel cell electrolyte

Journal of Solid State Electrochemistry - Proton-conducting BaZr1-xRExO3-δ (RE = Dy, Sm) (x = 0.05, 0.10, 0.15, 0.20) ceramics were synthesized via a conventional mixed...     

Natural Convection in a Spherical Porous Annulus: The Brinkman Extended Darcy Flow Model

The present study reports results of a numerical investigation of natural convection in a spherical porous annulus. The inner and outer surfaces are subjected to constant temperatures. The Brinkman extended Darcy flow model is considered in this study. The problem has been solved numerically employing successive accelerated replacement scheme. The effect of parameters like Rayleigh number, Darcy number and radius ratio on the fluid flow and heat transfer has been examined. There exists a critical radius ratio $(\mathrm{rr} = 3)$ at which the average Nusselt number attains a peak value. The average Nusselt number decreases as the Darcy number increases.