Regio-selective synthesis of 1,2-aminoalcohols from epoxides and chlorohydrins

A simple and efficient procedure for the regio-selective synthesis of 1,2-aminoalcohols from terminal epoxides and chlorohydrins by using NaHMDS as the source of amine is reported. The wider scope and utility of this method is demonstrated.     

NMR Spin–Spin Coupling Constants in Polymethine Dyes as Polarity Indicators

Herein, we explore the use of spin–spin coupling constants (SSCCs) in merocyanine (MCYNE) dyes as indicators of polarity. For this purpose, we use Car–Parrinello hybrid quantum mechanics/molecular mechanics (QM/MM) to determine the structures of MCYNE in solvents of different polarity, followed by computations of the SSCCs by using QM/MM linear‐response theory. The molecular geometry of MCYNE switches between neutral, cyanine‐like, and zwitterionic depending on the polarity of the solvent. This structural variation is clearly reflected in the proton SSCCs in the polymethine backbone, which are highly sensitive to the dielectric nature of the environment; this mechanism can be used as a “polarity indicator” for different microenvironments. This result is highlighted by computing the SSCCs of the MCYNE probe in the cavity of the beta‐lactoglobulin protein. The computed SSCCs clearly indicate a non‐polar hydrophobic dielectric nature of this cavity.     

Structurally modified 1,10-phenanthroline based fluorophores for specific sensing of Ni2+ and Cu2+ ions

We report two fluorophores with open coordination sites for specific sensing of Ni(2+) and Cu(2+) ions via a simple synthetic route. The fluorescence activity was completely quenched on coordination of the metal ions with the phenanthroline ring present in the fluorophore as is clearly evident from the photophysical studies.     

Numerical visualization of counter rotating vortex ring formation ahead of shock tube generated vortex ring

Graphical Abstract  

     

Fast ionic conduction in cubic hafnium garnet Li<Subscript>7</Subscript>La<Subscript>3</Subscript>Hf<Subscript>2</Subscript>O<Subscript>12</Subscript>

A new member of the family of garnets with fast lithium ion conduction has been found with the composition Li₇La₃Hf₂O₁₂. The anion arrangement corresponds to the oxygen framework in garnets, e.g., in Ca₃Fe₂Si₃O₁₂. Hafnium is coordinated octahedrally while the lanthanum environment can be described as a distorted cube. Lithium occupies a large number of positions with tetrahedral, trigonal planar, and metaprismatic coordination. Li₇La₃Hf₂O₁₂ shows a lithium bulk ion conductivity of 2.4 × 10⁻⁴ Ω⁻¹ cm⁻¹ at room temperature with an activation energy of 0.29 eV.     

Study of gamma radiation induced damages and variation of oxygen enhancement ratio with radiation dose using Saccharomyces cerevisiae

In the present study, an attempt has been made to quantify Oxygen Enhancement Ratio (OER) and variation of OER as a function of dose with experimental and theoretical formulations using Saccharomyces cerevisiae D7, X2180 and rad 52. The study confirms that, the variation of OER with dose depends upon type of cell and repair proficiency of cells. A theoretical model has been formulated to estimate OER values. With the help of this model, OER value for any dose can be calculated in the exponential region of the survival curve without actually extending the experiment in that dose region.     

Enhanced response of microbial fuel cell using sulfonated poly ether ether ketone membrane as a biochemical oxygen demand sensor

The present study is focused on the development of single chamber microbial fuel cell (SCMFC) using sulfonated poly ether ether ketone (SPEEK) membrane to determine the biochemical oxygen demand (BOD) matter present in artificial wastewater (AW). The biosensor produces a good linear relationship with the BOD concentration up to 650 ppm when using artificial wastewater. This sensing range was 62.5% higher than that of Nafion^®. The most serious problem in using MFC as a BOD sensor is the oxygen diffusion into the anode compartment, which consumes electrons in the anode compartment, thereby reducing the coulomb yield and reducing the electrical signal from the MFC. SPEEK exhibited one order lesser oxygen permeability than Nafion^®, resulting in low internal resistance and substrate loss, thus improving the sensing range of BOD. The system was further improved by making a double membrane electrode assembly (MEA) with an increased electrode surface area which provide high surface area for electrically active bacteria.     

Pharmacophore modelling and electronic feature analysis of hydroxamic acid derivatives,the HIV integrase inhibitors

Hydroxamic acid derivatives with metal ion binding properties were collected from the literature to generate a pharmacophore and 3D-QSAR model for HIV strand transfer inhibition. The derived pharmacophore model (AAAHRR) recognizes both metal ion binding site and hydrophobic group. The QSAR model generated using this hypothesis expressed statistical significance (r ² = 0.971 for the training set and q ² = 0.913 for the test set). The ability of this pharmacophore model to retrieve other metal ion binding inhibitors was examined by screening the ChemBank database (ligandinfo) incorporated with 10 known strand transfer inhibitors. The studied favourable and unfavourable contours of chemical features (H-bond donor, acceptor and hydrophobic sites) revealed the role of hydrophobic substitution at the fluorobenzene ring and cyclization of the metal ion binding hydroxamic acid in effective integrase inhibition. Analysis of the frontier orbitals, HOMO and LUMO revealed that the nucleophilic / electrophilic interactions depend on the significant overlapping observed at the azaindole and hydroxamic acid groups. In essence, the generated pharmacophore model is competent enough to disclose the essential site-specific interactions involved in the inhibition of HIV integrase, and hence can be used in virtual screening to identify novel scaffolds as leads with increased anti-viral potency.