Chemical Detoxification of Organomercurials

Organomercurials including methylmercury are ubiquitous environmental pollutants and highly toxic to humans. Now it could be shown that N‐methylimidazole based thiones/selones having an N‐CH₂CH₂OH substituent are remarkably effective in detoxifying various organomercurials to produce less toxic HgE (E=S, Se) nanoparticles. Compounds lacking the N‐CH₂CH₂OH substituent failed to produce HgE nanoparticles upon treatment with organomercurials, suggesting that this moiety plays a crucial role in the detoxification by facilitating the desulfurization and deselenization processes. This novel way of detoxifying organomercurials may lead to the discovery of new compounds to treat patients suffering from methylmercury poisoning.     

CuInGaSe nanocrystals for detection of trace amount of water in D2O (at ppm level)

Herein, we describe synthesis of copper indium gallium selenide (CIGS) nanocrystals by sol–gel method at room temperature, and the optimization of In/Ga ratio revealed best results pertained to Cu_0.19In_0.24Ga_0.76Se_2.7 composition. The morphology and crystal structure of these nanocrystals were ascertained from scanning electron microscopy (SEM) and X‐ray diffraction (XRD) studies. These nanocrystals were dispersed in D₂O‐H₂O binary mixture and these samples were probed for the presence of H₂O at ppm level (between 9 to 117 ppm) using fluorescence spectroscopy. The fluorescence intensity at the emission wavelength of 485 nm was found to increase with water content, and hence it operated as an excellent water sensor with a fast response time. It was also noted that observable color change of CIGS dispersion made in ethanol occurred, when trace amount of water was added confirming the water sensing ability of this nanomaterial in different environment. Our reproducible experimental results show that CIGS nanocrystals are promising candidate for water detection in D₂O at ppm level at room temperature operations. Considering the importance of purity of D₂O in nuclear reactors, these results are of remarkable importance.     

Evidence from Raman spectroscopy that InhA, the mycobacterial enoyl reductase, modulates the conformation of the NADH cofactor to promote catalysis

InhA, the enoyl reductase from Mycobacterium tuberculosis, catalyzes the NADH-dependent reduction of trans-2-enoyl-ACPs. In the present work, Raman spectroscopy has been used to identify catalytically relevant changes in the conformation of the nicotinamide ring that occur when NADH binds to InhA. For 4(S)-NADD, there is an 11 cm-1 decrease in the wavenumber of the C4-D stretching band (nuC-D) and a 50% decrease in the width of this band upon binding to InhA. While a similar reduction in line width is observed for the corresponding band arising from 4(R)-NADD, nuC-D for this isomer increases 34 cm-1 upon binding to InhA. These changes in nuC-D indicate that the nicotinamide ring adopts a bound conformation in which the 4(S)C-D bond is in a pseudoaxial orientation. Mutagenesis of F149, a conserved active site residue close to the cofactor, demonstrates that this enzyme-induced modulation in cofactor structure is directly linked to catalysis. In contrast to the wild-type enzyme, Raman spectra of NADD bound to F149A InhA resemble those of NADD in solution. Consequently, F149A is no longer able to optimally position the cofactor for hydride transfer, which correlates with the 30-fold decrease in kcat and 2-fold increase in D(V/KNADH) caused by this mutation. These studies thus substantiate the proposal that hydride transfer is promoted by pseudoaxial positioning of the NADH pro-4S bond, and indicate that catalysis of substrate reduction by InhA results, in part, from correct orientation of the cofactor in the ground state.     

Ion Conducting Polyethylene Oxide-Based Polymer Electrolyte Dopped with Ionic Liquid-Trifluoromethanesulfonic Chloride

In last few decades, polymer electrolyte is the most promising candidate for the fabrication of electrochemical devices. In current work, the influence of adding the room-temperature ionic liquid (trifluoromethanesulfonic chloride – CClF3O2S) in polyethylene oxide (PEO): ammonium iodide (NH4I) polymer electrolyte has been studied. The IL-doped polymer electrolyte films are synthesized by solution casting method with varying stoichiometric ratios. Several experimental techniques including optical polarizing microscope, impedance spectroscopy, X-ray diffraction, Linear sweep voltammetry, Ionic transference number thermal analysis, and electrical conductivity measurements at room temperature have been studied in detail. The complex material's maximum conductivity has been determined to be 3.3 × 10⁻⁵ S cm⁻¹ at room temperature. The POM images show the increase in amorphous region which further confirm the improvement in ionic conductivity. Ionic transference number 0.96 shows the system is purely ionic in nature. The ESW of the IL doped polymer electrolyte is also sawed to be 3.32 V which is suitable for the fabrication of electrochemical devices.     

Photocatalytic Degradation of Orange G Dye by Using Bismuth Molybdate: Photocatalysis Optimization and Modeling via Definitive Screening Designs

In the current study, Bismuth molybdate was synthesized using simple co-precipitation procedure, and their characterization was carried out by various methods such as FT-IR, SEM, and P-XRD. Furthermore, the photocatalytic degradation of Orange G (ORG) dye using synthesized catalyst under visible light irradiation was studied. Response surface Method was used for the optimization of process variables and degradation kinetics evaluated by modeling of experimental data. Based on the experimental design outcomes, the first-order model was proven as a practical correlation between selected factors and response. Further ANOVA analysis has revealed that only two out of six factors have a significant effect on ORG degradation, however ORG concentration and irradiation time indicated the significant effects sequentially. Maximum ORG degradation of approximately 96% was achieved by keeping process parameters in range, such as 1 g L⁻¹ loading of catalyst, 50 mg L⁻¹ concentration of ORG, 1.4 mol L⁻¹ concentration of H₂O₂ at pH 7 and a temperature of 30 °C. Kinetics of ORG degradation followed the pseudo first order, and almost complete degradation was achieved within 8 h. The effectiveness of the Bi₂MoO₆/H₂O₂ photo-Fenton system in degradation reactions is due to the higher number of photo-generated e- available on the catalyst surface as a result of their ability to inhibit recombination of e- and h+ pair.     

Disappearance of intramolecular stacking due to one‐atom movement or increment of a `propyl­ene linker' in pyrazolo­[3,4‐d]­pyrimidine‐based ­flexible models

In the crystal structures of 4,6‐di­methyl­thio‐1‐[3‐(4,6‐di­methyl­thio‐2H‐pyra­zolo­[3,4‐d]­py­rimi­din‐2‐yl)­propyl]‐1H‐py­ra­­zolo­[3,4‐d]­py­rimi­dine, C₁₇H₂₀N₈S₄, and 1‐[4‐(4‐meth­oxy‐6‐methyl­thio‐1H‐pyra­zolo­[3,4‐d]py­rimi­din‐1‐yl)­butyl]‐5‐meth­yl‐6‐methyl­thio‐4,5‐di­hydro‐1H‐pyra­zolo­[3,4‐d]py­rimi­din‐4‐one, C₁₈H₂₂N₈O₂S₂, only intermolecular stacking due to aromatic π–π interactions between pyrazolo­[3,4‐d]­pyrimidinerings is present.     

A facile enantioselective synthesis of (S)-N-(5-chlorothiophene-2-sulfonyl)-β,β-diethylalaninol via proline-catalyzed asymmetric α-aminooxylation and α-amination of aldehyde

A high-yielding enantioselective synthesis of the bioactive (S)-N-(5-chlorothiophene-2-sulfonyl)-β,β-diethylalaninol (1), a Notch-1-sparing γ-secretase inhibitor metabolite (with EC₅₀ = 28 nM) effective in reduction of Aβ production in vivo, has been realized starting from readily available 3-pentanone. The key steps of the synthesis are proline-catalyzed α-aminooxylation and α-amination of aldehyde; the latter contributing an overall yield of 45.2% and 98% ee.