A Post‐Synthetically Modified MOF for Selective and Sensitive Aqueous‐Phase Detection of Highly Toxic Cyanide Ions

Selective and sensitive detection of toxic cyanide (CN^?) by a post‐synthetically altered metal–organic framework (MOF) has been achieved. A post‐synthetic modification was employed in the MOF to incorporate the specific recognition site with the CN^? ion over all other anions, such as Cl^?, Br^?, and SCN^?. The aqueous‐phase sensing and very low detection limit, the essential prerequisites for an effective sensory material, have been fulfilled by the MOF. Moreover, the present detection level meets the standard set by the World Health Organization (WHO) for the permissible limit of cyanide concentration in drinking water. The utilization of MOF‐based materials as the fluorometric probes for selective and sensitive detection of CN^? ions has not been explored till now.     

Four-component,one-pot synthesis of spiropyrazolo pyrimidine derivatives by using recyclable nanocopper ferrite catalyst and antibacterial studies

A simple, efficient, ecofriendly, and cost-effective method has been developed for the synthesis of 16 spiropyrazolo pyrimidine derivatives (5a–5p) by a four-component, one-pot reaction of pyrimidine-2,4,6(1H,3H,5H)-trione, 3-oxo-3-phenylpropanenitrile, hydrazine, and isatins (4a–4f) by using nanocopper ferrite catalyst (20?mol%) in water with excellent yields (73–91%). The isatin with electron-withdrawing groups gave products in high yields (5h and 5p). The present methodology offers an environmentally benign, cost-effective, high-yielding method with recyclable catalyst. The drug likeness or “drugability” of all the synthesized compounds were tested through rule of five (RO5) parameters. Compounds 5f, 5h, 5n, and 5p have shown one RO5 violation each. The compounds were screened for their antibacterial activity against human pathogenic bacteria wherein two of the synthesized compounds were found to possess significant antibacterial activity. Compounds showing RO5 violations had negligible antibacterial activity.     

Effect of swift heavy ion irradiation on dilute Fe-doped Sb0.95Se0.05 magnetic semiconductor

A thin film of dilute Fe (0.008)-doped Sb_0.95Se_0.05 alloy was grown on silicon substrate using the thermal evaporation technique. This film was irradiated with swift heavy ions (SHIs) Ag⁺¹⁵ having 200?MeV energy at ion fluences of 1?×?10¹² and 5?×?10¹² ions per cm², respectively. The thickness of the thin film was ～500?nm. We study the effect of irradiation on structural, electrical, surface morphology and magnetic properties of this film using grazing angle XRD (GAXRD), DC resistivity, atomic force microscopy (AFM) and magnetic force microscopy (MFM), respectively. GAXRD suggests that no significant change is observed in this system due to SHI irradiation. The average crystallite size increases with fluence, whereas the AFM image shows the rms roughness decreases due to irradiation with respect to the un-irradiated thin film. The MFM image shows that the magnetic interaction in irradiated film decreases due to the irradiation effect. Although the un-irradiated sample shows metal to semiconducting transition, but after irradiation with fluence of 5?×?10¹² ions per cm², the sharpness of the metal to semiconducting phase transition is observed to increase dramatically at ～300?K. This characteristic of the thin film makes it a promising candidate for an electrical switching device after irradiation.     

Sulfamic acid: an efficient, cost-effective and recyclable solid acid catalyst for the Friedlander quinoline synthesis

o-Aminoaryl ketones undergo smooth condensation with α-methylene ketones in the presence of sulfamic acid (NH₂SO₃H) (SA) under mild reaction conditions to afford the corresponding polysubstituted quinolines in excellent yields. The catalyst can be recovered by simple filtration and can be recycled in subsequent reactions. The method is simple, cost-effective and environmentally benign.     

Testing linear hypotheses in errors in variables model

A multivariate errors-in-variables model in the matrix form can be written as X=U+E, Y=UA+WB+F, where X (n×p) and Y (n×q) are observed matrices, E and F are error matrices whose rows are normally distributed, W (n×k) is a known matrix of rank k, and U, A and B are unknown matrices. We consider the problems of testing linear hypotheses: (i) H ₀: AR=K and (ii) H ₀: SA=L, where R, K, S and L are known matrices, and we derive the likelihood ratio tests for testing these hypotheses.     

Spectrophotometric,Thermodynamic and Density Functional Studies of Charge Transfer Complex Between Benzhydryl Piperazine and 2,3-Dichloro-5,6-dicyano-1,4-benzoquinone

The charge transfer complex of benzhydryl piperazine as donor with the π-acceptor 2,3-dichloro-5,6-dicyano-p-benzoquinone has been studied spectrophotometrically in acetonitrile medium at different temperatures. On mixing the donor with acceptor, a reddish brown colored charge transfer complex is formed. Electronic absorption spectra of the complex show charge transfer bands at 587, 546 and 457 nm. The molecular composition of the complex was studied by applying Job’s continuous variation and spectrophotometric titration methods. These results support the formation of the complex in a 1:2 ratio. The Benesi–Hildebrand equation has been applied to compute the formation constant and molecular extinction coefficient. Thermodynamic parameters of the charge transfer complexation reaction (standard entropy, standard enthalpy and standard Gibbs free energy) have been calculated. The results of the spectrophotometric study demonstrated that the charge transfer complex formation is endothermic. The computational studies of the charge transfer complex were performed by using the Gaussian 09 W package of programs. The bond lengths, bond angles, dihedral angles, Mulliken atomic charges, molecular electrostatic potential maps and characterization of the highest occupied molecular orbital and lowest unoccupied molecular orbital surfaces of charge transfer complex were computed.     

Urea mediated 5-substituted-1H-tetrazole via [3 + 2] cycloaddition of nitriles and sodium azide

A simple, new and convenient metal free procedure for the synthesis of 5-substituted 1H-tetrazoles using various nitriles and sodium azide in the presence of urea and acetic acid with good to high yields is developed. The reaction plausibly proceeds through in situ formation of urea azide active complex without toxic and/or expensive metal catalysts.     

Novel sphingolipids from Conyza canadensis

New sphingolipids, 1,3,5-trihydroxy-2-hexadecanoylamino-(6E,9E)-heptacosdiene (1). 1,3,5-trihydroxy-2-hexadecanoylamino-(6E,9E)-heptacosdiene-1-O-glucopyranoside (2). 1,3-dihydroxy-2-hexanoylamino-(4E)-heptadecene (3). have been isolated from Conyza canadensis, along with five known compounds, p-hydroxybenzoic acid, 3,5-dihydroxybenzoic acid, 3,5-dimethoxybenzoic acid, 3beta-hydroxyolean-12-en-28-oic acid, and 3beta-erythrodiol, isolated for the first time from this species. Their structures were determined by spectroscopic methods ((1)H- and (13)C-NMR, IR and MS) and two dimensional (2D)-NMR experiments.     

Synthesis of β-peroxy-lactones using 30% H2O2

Cyclopropyl carbinols 1a-e react with H₂O₂ in the presence of concd H₂SO₄ at 0-5 °C to furnish the corresponding hydroperoxides 2a-e in 45-82% yields. This efficient trapping of cyclopropylmethyl cations by the hydroperoxy group has been exploited to prepare compounds 14-23, a new series of cyclopropyl substituted β-peroxy-lactones.     

Desulfurization of sour crude oil using an invasive weed adsorbent: An efficient,eco-friendly,and ultra-low-cost option

Desulfurization is a technology commonly used by refineries to mitigate the environmental burden caused by toxic gas emissions from hydrocarbon fuels. Expanding global population will increase liquid fuel demand by 20% between 2018 and 2050, with a total consumption of 240 quadrillion British thermal units (Btu) in 2050. Conventional catalytic Hydrodesulfurization (HDS) accounts for high cost and severe operating conditions (high temperature, pressure, catalyst poisoning and H₂S safety). While studies have shown that adsorptive desulfurization (ADS) is highly effective in the removal of organic sulfur, limitations in the regeneration of adsorbent and selection of adsorbent with suitable structure to remove organic sulfur compounds exist. On the other hand, Prosopis juliflora, the world's most threatening invasive weed causes multifaceted environmental problems. The present study offers a novel solution that addresses both these issues contributing to climate change. Desulfurization of sour crude oil sample is performed using chemical-free, non-activated charcoal obtained from invasive weed species as adsorbent. XRD analysis showed amorphous structure and FTIR analysis confirmed the presence of CC bending functional group of the adsorbent. Adsorption-desorption isotherm showed presence of mesopores with pore diameter of 2.718 ?nm. Kinetic study findings reported 46% removal of total sulfur. GCMS findings showed efficient removal of some organic sulfur, including 100% removal of dibenzothiophene 4-methyl -. The equilibrium data is best represented by Freundlich isotherm. ICP-OES tests indicate the removal of toxic elements as well. The cost of the adsorbent is USD 0.12628 per kg, the lowest among all the adsorbents known thus far. The present study describes a novel, ultra-low cost, efficient, eco-friendly, desulfurization process that implements a chemical-free, non-activated adsorbent, achieves synergy, and offers multi-dimensional benefits to the environmental development. To our knowledge, this is the first study to characterize desulfurization of sour crude oil using an invasive weed.