CO2 and SnII Adducts of N‐Heterocyclic Carbenes as Delayed‐Action Catalysts for Polyurethane Synthesis

Catalytic rivals : Both CO₂‐protected tetrahydropyrimidin‐2‐ylidene‐based N‐heterocyclic carbenes (NHCs) and Sn^II‐1,3‐dimesitylimidazol‐2‐ylidene, as well as Sn^II‐1,3‐dimesitylimidazolin‐2‐ylidene complexes (example displayed), have been identified as truly latent catalysts for polyurethane (PUR) synthesis rivaling all existing systems both in activity and latency.

     

Expedient Synthesis of Core Disaccharide Building Blocks from Natural Polysaccharides for Heparan Sulfate Oligosaccharide Assembly

The complex sulfation motifs of heparan sulfate glycosaminoglycans (HS GAGs) play critical roles in many important biological processes. However, an understanding of their specific functions has been hampered by an inability to synthesize large numbers of diverse, yet defined, HS structures. Herein, we describe a new approach to access the four core disaccharides required for HS/heparin oligosaccharide assembly from natural polysaccharides. The use of disaccharides rather than monosaccharides as minimal precursors greatly accelerates the synthesis of HS GAGs, providing key disaccharide and tetrasaccharide intermediates in about half the number of steps compared to traditional strategies. Rapid access to such versatile intermediates will enable the generation of comprehensive libraries of sulfated oligosaccharides for unlocking the “sulfation code” and understanding the roles of specific GAG structures in physiology and disease.     

Dye Pollutants removal from Waste water using Metal Oxide Nanoparticle embedded Activated Carbon: An Immobilization study

This study evaluated the feasibility of Rhodamine-B dye (Rh B) removal from aqueous solution, using Lead-Iron Oxide nanoparticles Loaded Activated Carbon (FePbO@AC). The parameters like pH, contact time, adsorbent/adsorbate dosage and temperature on adsorption was studied. Optimized conditions are pH of 7.0, 25?min contact time, 50?ppm of dye concentration and 200?mg of adsorbent concentration. The kinetics of adsorption was calculated using pseudo-first-order, pseudo-second-order, and intra-particle diffusion models. The calculations revealed that the pseudo-second-order kinetic equation best-fit the adsorption data. The Langmuir isotherm model best fit the equilibrium data. The maximum sorption capacity (Q_max) for dye is 1000?mg Rh B/g FePbO@AC. Change in entropy (ΔS), Gibb’s free energy change (ΔG), and enthalpy (ΔH) were calculated for the adsorption of Rh B dye.     

Synthesis,antimicrobial, and antioxidant activities of new pyridyl‐ and thiazolyl‐bearing carbohydrazides

A series of novel substituted (E)‐N′‐benzylidene‐4‐methyl‐2‐(2‐propylpyridin‐4‐yl)thiazole‐5‐carbohydrazide derivatives ( 6a‐l ) have been synthesized by following the multistep synthetic route starting from prothionamide. The resulting compounds were characterized via ¹H, ¹³C NMR, and HRMS spectral data. The synthesized carbohydrazides were evaluated for their in vitro antimicrobial and antioxidant activities. Tested molecules have displayed moderate to good growth inhibition activity. Among the screened compounds, 6b , 6e , 6j, and 6k are found to be the more promising antimicrobial agents. A 2,2‐diphenyl‐1‐picrylhydrazyl assay was used to test the antioxidant activity of the carbohydrazides. The carbohydrazide derivatives 6b and 6i have shown better free‐radical scavenging ability than the other investigated compounds.     

Fluorine-doped zinc oxide transparent and conducting electrode by chemical spray synthesis

Highly transparent and conducting fluorine-doped zinc oxide thin films, consisting of spherical nanometer-sized grains, were synthesized onto soda-lime glass substrate by using a chemical spray unit. The effect of fluorine doping concentration in starting solution was investigated. Both doped and undoped films were preferentially oriented along [002] direction. Electrical resistivity decreases from 5.7 x 10^-2 to 8.6 x 10^-3 ohm-cm after 1 at.% fluorine doping, and increases for higher doping concentration. However, surface morphology of films obtained at 3 at.% fluorine doping appeared smooth and uniform. A shift of the edge of the optical transmission in the ultraviolet region as a result of fluorine doping was obtained.     

Studies on stability of PEC cells formed with CdS:Al films

Aluminum doped and undoped CdS films are deposited on stainless steel substrates by chemical bath deposition technique and are employed in PEC cells. The effects of heat treatment to photoanode and addition of salts like KCl and NaCl in an electrolyte on the stability of the PEC cells are studied. It is found that though the PEC cells formed with CdS films are stable in NaOH-Na₂S-S electrolyte, the stability of PEC cells formed with Al doped CdS films is achieved only after the addition of saturated salts in the electrolyte.     

Electrosynthesis and characterization of Fe doped CdSe thin films from ethylene glycol bath

The CdSe and Fe doped CdSe (Fe:CdSe) thin films have been electrodeposited potentiostatically onto the stainless steel and fluorine doped tin oxide (FTO) glass substrates, from ethylene glycol bath containing (CH₃COO)₂·Cd·2H₂O, SeO₂, and FeCl₃ at room temperature. The doping concentration of Fe is optimized by using (photo) electrochemical (PEC) characterization technique. The deposition mechanism and Fe incorporation are studied by cyclic voltammetry. The structural, surface morphological and optical properties of the deposited CdSe and Fe:CdSe thin films have been studied by X-ray diffraction, scanning electron microscopy (SEM) and optical absorption techniques respectively. The PEC study shows that Fe:CdSe thin films are more photosensitive than that of undoped CdSe thin films. The X-ray diffraction analysis shows that the films are polycrystalline with hexagonal crystal structure. SEM studies reveal that the films with uniformly distributed grains over the entire surface of the substrate. The complete surface morphology has been changed after doping. Optical absorption study shows the presence of direct transition and a considerable decrease in bandgap, E_g from 1.95 to 1.65 eV.     

Cadmium selenide microspheres as an electrochemical supercapacitor

This paper reports the synthesis of cadmium selenide electrodes by simple and cost effective chemical bath deposition method for the electrochemical supercapacitors. In order to study the effect of deposition time onto the morphological and electrochemical performance of CdSe electrodes, the reaction time was varied from 2 h to 10 h. As the reaction time goes on increasing the voide-less uniform growth of the thin films with increased size and density of CdSe microspheres is observed from field emission microscopy study. The supercapacitive behavior of the prepared electrodes were analysed with the help of electrochemical impedance, cyclic voltammetry and charge/discharge measurements. The areal capacitance is found to increase from 0.30 mFcm^?2 to 1.285 mFcm^?2 with respect to the deposition time, this indicates the positive effect towards the electrochemical performance.