Biocatalysis for C–S bond formation: Porcine pancreatic lipase (PPL) catalysed thiolysis/hydrothiolation reactions in sole water

In this paper, a biocatalytic route is described wherein PPL, lipase from porcine pancreas, in conjunction with water on reaction with different thiophenols and styrene oxides undergo thiolysis with C-S bond formation without the use of any metal catalysts, oxidants, bases, additives or organic solvents towards formation of β-hydroxysulfides in good to excellent yields with high regioselectivity at room temperature. Furthermore, PPL also facilitates thiophenols to undergo hydrothiolation with styrenes or phenylacetylenes in sole water and thus forming linear thioethers or vinylsulfides respectively via C–S bond formation. In addition to the straightforward and atom-efficient protocol, a gram-scale synthesis of β-hydroxysulfide and recyclability for three consecutive cycles without decrease in efficiency of PPL make our biocatalytic protocol for constructing C–S bond highly valuable from both environmental and economic viewpoints than traditional chemical practices.     

Evaluation of eigenvalues of a smooth potential via Schroedinger transmission across multi-step potential

In a one-dimensional quantal solution of Schroedinger equation, the general expressions for reflection and transmission coefficients are derived for a potential constituting n number of rectangular wells and barriers. These expressions are readily used for the estimation of eigenvalues of a smooth potential which is simulated by a multi-step potential. The applicability of this method is demonstrated with success in potentials with different forms including the most versatile Ginocchio potential where the widely used numerical method like Runge-Kutta integration algorithm fails to yield the result. Accurate evaluation of eigenvalues free from numerical problem for any form of potentials, whether analytically solvable or not, is the highlight of the present multi-step approximation method in the theory of potential scattering.      

Functional analysis of repositioned anilide derivatives as anticancer compounds

Off the different types cancers 40% of the population have been observed to be affected by leukemia. Contemporary therapeutics is focusing on generation of new synthetic analogues that can exert maximum positive physiological effect with minimum dosage and negligible deleterious side effects. New generation pharmacists are focusing on such promising effects of Imatinib (a potential anti-cancer drug molecule), Dasatinib, Pelitinib and Nilotinib. The present research study focuses on novel synthesized anilides derivative against BCR-ABL kinase as potential anti-leukemic agent. Validation of the compounds by molecular docking with specific BCR-ABL kinase confirmed their activity. Toxicity prediction of these compounds helped to identify sustainability as therapeutic molecules. The IC₅₀ values were calculated (211 ug, 175 ug, 272ug for compounds A, B, C resp.) and the mode of cell death was gauged by DNA laddering assay. The cells were observed to be induced for programmed cell death. By validating and in-vivo testing of three synthesized compounds, the compound B was observed to be more stable thermodynamically with a potentially vital active site and appears to be a promising anti-leukemic factor. The present research thus lays a preliminary platform in world of pharmaceutics, where these new analogues appear to be efficient, target specific and less toxic molecules.     

Uranium in ground water of Rajnandgaon District of Central India

The present study highlights uranium levels, associated health effects, and physicochemical properties of ground water samples collected from Rajnandgaon District of Chhattisgarh State, Central India. Uranium concentrations of ground water samples are found to exceed than 30 µg/L (United States Environmental Protection Agency and World Health Organisation recommended limit) at two villages in summer and at one village in winter while it is found higher than 60 µg/L (Atomic Energy Regulatory Board, Department of Atomic Energy, India recommended limit) at only one village in summer. Correlation analysis between uranium and physicochemical parameters suggest that Ca²⁺ ion and total alkalinity play an important role in uranium contamination of ground water.

     

Aggregation‐Induced and Polymorphism‐Dependent Thermally Activated Delayed Fluorescence (TADF) Characteristics of an Oligothiophene: Applications in Time‐Dependent Live Cell Multicolour Imaging

Typically, molecules with a twisted donor–acceptor (D‐A) architecture have been exploited for constructing thermally activated delayed fluorescence (TADF) materials. Herein, we report the first example of a thiophene‐based thermally activated delayed fluorescent molecule without a D‐A architecture. Compound 1 (2,5‐bis(2,2‐di(thiophen‐2‐yl)vinyl)thiophene) is conformationally flexible and shows weak fluorescence in the solution state but displays bright TADFin both condensed and solid states. Compound 1 crystallized in two different polymorphs ( 1 a and 1 b ). Interestingly, both polymorphs show distinctly different TADF features. The broad spectral features and the TADF characteristics of 1 have been explored for the time‐dependent multicolor (green, yellow and red) imaging of living cells.     

Synthesis of (−)-elemoxide,a commercially important fragrance compound

(?)-Elemoxide, a fragrant compound was synthesised using commercially available elemol in four steps with overall yield of 32%. The cyclic ether skeleton was constructed via intramolecular hydroalkoxylation using I₂ and PhSiH₃ catalytic system. Also, intramolecular oxymercuration-demercuration was employed as an alternate approach for cyclization. The various regioselective strategies involving epoxidation of alkene, reduction of epoxide and intramolecular cyclization were the highlights of the work. The key intermediate diol serves as a versatile intermediate for the synthesis of elemoxide and elemene.     

A simple approach for the synthesis of azocine alkaloids: The total synthesis of megallanesine

A new three step synthetic route to construct azocine ring system using anion chemistry and intramolecular Friedel-Craft reaction of an ester is presented. This method allows synthesis of azocine ring analogues in excellent overall yields. The designed strategy was applied for the synthesis of naturally occurring magallanesine.     

Direct Analysis of Proteins from Solutions with High Salt Concentration Using Laser Electrospray Mass Spectrometry

The detection of lysozyme, or a mixture of lysozyme, cytochrome c, and myoglobin, from solutions with varying salt concentrations (0.1 to 250 mM NaCl) is compared using laser electrospray mass spectrometry (LEMS) and electrospray ionization-mass spectrometry (ESI-MS). Protonated protein peaks were observed up to a concentration of 250 mM NaCl in the case of LEMS. In the case of ESI-MS, a protein solution with salt concentration >?0.5 mM resulted in predominantly salt-adducted features, with suppression of the protonated protein ions. The constituents in the mixture of proteins were assignable up to 250 mM NaCl for LEMS and were not assignable above a NaCl concentration of 0.5 mM for ESI. The average sodium adducts (< n >) bound to the 7+ charge state of lysozyme for LEMS measurements from salt concentrations of 2.5, 25, 50, and 100 mM NaCl are 1.71, 5.23, 5.26, and 5.11, respectively. The conventional electrospray measurements for lysozyme solution containing salt concentrations of 0.1, 1, 2, and 5 mM NaCl resulted in < n > of 2.65, 6.44, 7.57, and 8.48, respectively. LEMS displays an approximately two orders of magnitude higher salt tolerance in comparison with conventional ESI-MS. The non-equilibrium partitioning of proteins on the surface of the charged droplets is proposed as the mechanism for the high salt tolerance phenomena observed in the LEMS measurements.

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Graphical Abstract ?

     

Visible‐Light Photocatalysis: Does It Make a Difference in Organic Synthesis?

Visible‐light photocatalysis has evolved over the last decade into a widely used method in organic synthesis. Photocatalytic variants have been reported for many important transformations, such as cross‐coupling reactions, α‐amino functionalizations, cycloadditions, ATRA reactions, or fluorinations. To help chemists select photocatalytic methods for their synthesis, we compare in this Review classical and photocatalytic procedures for selected classes of reactions and highlight their advantages and limitations. In many cases, the photocatalytic reactions proceed under milder reaction conditions, typically at room temperature, and stoichiometric reagents are replaced by simple oxidants or reductants, such as air, oxygen, or amines. Does visible‐light photocatalysis make a difference in organic synthesis? The prospect of shuttling electrons back and forth to substrates and intermediates or to selectively transfer energy through a visible‐light‐absorbing photocatalyst holds the promise to improve current procedures in radical chemistry and to open up new avenues by accessing reactive species hitherto unknown, especially by merging photocatalysis with organo‐ or metal catalysis.