Understanding behaviour of vitamin-C guest binding with the cucurbit[6]uril host

The present study describes non-covalent interaction and complexation behaviour of sodium ascorbate (SA) with cucurbit[6]uril (CB[6]) at neutral pH in aqueous Na₂SO₄ solution. The interaction behaviour is investigated using various analytical techniques like NMR, UV–Vis, fluorescence, TGA and DRS. The substantial increase in the intensity of emission and absorption spectra of sodium ascorbate is observed. The Benesi–Hildebrand evaluation method is used to determine the stoichiometry and equilibrium constant of the cucurbit[6]uril–sodium ascorbate complex, which suggested the 1:1 complex. Time-dependent ¹H NMR, ¹³C CP MAS and CD studies also echoed non-covalent interaction between SA with CB[6].     

An InBr3 catalyzed one-pot three-component synthesis of functionalized spirodihydrofuran oxindoles via intramolecular alkyne carbonyl metathesis

A new and convenient one-pot methodology for the reaction of N-methyl isatin, alkynes and phenacyl bromides to selectively afford spiro dihydrofuran oxindole derivatives catalyzed by indium bromide under ambient temperature conditions has been documented. The method has been applied for the synthesis of a range of compounds with variable functionalities in good to excellent yields (76–92%). The significant advantages of this protocol are highlighted by excellent yields, cleaner reaction profiles and avoidance of expensive catalysts.     

Synthesis of imidazo[1,2-a]pyridine in the presence of iodine–water catalytic system

We have devised an expedient, cleaner, and environmentally friendly approach for ‘on water’ mediated synthesis of imidazo[1,2-a]pyridine derivatives. The synthesis involves in situ formation of imines followed by addition of alkyne to give the desired products in excellent yield.     

Effects of increasing number of rings on the ion sensing ability of CdSe quantum dots: a theoretical study

A computational study on the structural and electronic properties of a special class of artificial atoms, known as quantum dots, has been carried out. These are semiconductors with unique optical and electronic properties and have been widely used in various applications, such as bio-sensing, bio-imaging, and so on. We have considered quantum dots belonging to II–VI types of semiconductors, due to their wide band gap, possession of large exciton binding energies and unique optical and electronic properties. We have studied their applications as chemical ion sensors by beginning with the study of the ion sensing ability of (CdSe) _n (n?=?3, 6, 9 which are in the size range of ~?0.24, 0.49, 0.74 nm, respectively) quantum dots for cations of the zinc triad, namely Zn²⁺, Cd²⁺, Hg²⁺, and various anions of biological and environmental importance, and studied the effect of increasing number of rings on their ion sensing ability. The various structural, electronic, and optical properties, their interaction energies, and charge transfer on interaction with metal ions and anions have been calculated and reported. Our studies indicate that the CdSe quantum dots can be employed as sensors for both divalent cations and anions, but they can sense cations better than anions.     

Molecular docking and dynamic simulation of approved drugs targeting against spike protein (6VXX) of 2019-nCoV (novel coronavirus)

The 2019-nCoV has triggered a global public health emergency due to its rapid spread, resulting in a pandemic situation. Because of its ability to bind with the host cell receptor ACE-2, the spike protein of the 2019-nCoV is a critical factor in viral infection. The current study aims to investigate the molecular-docking of the spike protein (6VXX) using PyRx for FDA-approved drugs available for the treatment of SARS-1 and MERS, with the hypothesis that these drugs could be suggested for the treatment of 2019-nCoV or not. A phylogenetic analysis of 2019-nCoV in relation to SARS-1 and MERS confirmed the validation. The positive result urged the Multiple Sequence Alignment analysis of the top five affected countries, with China serving as a control, using WHO available reference data to determine the rate of mutant variation. The docking results revealed that the top ten drugs with the highest binding affinity rate are also used for Hepatitis-C virus treatment, and the Molecular Dynamic Simulation was carried out for the drug Paritaprevir, which had the highest binding affinity rate, using Gromacs. The results indicated that the drug Paritaprevir could be used as a potential target against the 2019-nCoV Spike protein.     

Acousto-electric wave instability in ion-implanted semiconductor plasmas

A comprehensive investigation of excitation of acousto-electric modes and novel properties introduced due to presence of negatively charged colloids in magnetized compensated piezoelectric semiconductor plasma is presented analytically. We derive a compact dispersion relation for the acousto-electric waves in colloids laden semiconductor plasma by employing multi-fluid balance equation. It is found that the presence of charged colloids not only modifies the wave spectrum but also alters the amplification characteristics even though colloidal particles, on account of their heavy masses, do not participate in wave propagation. The results of this investigation should be useful in understanding the characteristics of longitudinal acousto-electric wave in ion-implanted piezoelectric semiconductor plasmas whose main constituents are electrons, holes and negatively charged colloids, which are stationary in the background.     

Zirconia supported undecatungstophosphate: synthesis and characterization of a bifunctional catalyst

The synthesized supported undecatungstophosphate has been proven to be successful for acid catalyzed as well as oxidation reactions, especially, in obtaining 98.5% conversion of styrene and 100% selectivity for benzaldehyde.     

Catalyst‐Free Convergent Approach for the Synthesis of Spiro[imidazo[2,1‐b][1,3]oxazine‐7,3′‐indoline

Strategies to address mounting environmental concerns with current approaches include an operationally simple and highly efficient one‐pot three‐component approach for the synthesis of spiro[imidazo[2,1‐b][1,3]oxazine‐7,3′‐indoline derivatives, which has been developed via Huisgen zwitter ion intermediate. The significant advantages of this protocol are short reaction time, excellent yields, and facile formation of three new bonds in one operation from easily available starting materials.     

Application of Privileged Molecular Framework of 7‐Fluoro‐1,4‐benzodiazepin‐2‐one‐5‐methylcarboxylate to the Synthesis of Its 1‐ and 5‐Disubstituted Analogs of Medicinal Interest

Synthetic potential of the privileged molecular framework of 7‐fluoro‐1,4‐benzodiazepin‐2‐one containing a methyl carboxylate substituent at its 5‐position was exploited to develop efficient protocols to the synthesis of several novel 5‐(1′,3′,4′)oxadiazole ring incorporated analogs of medicinal interest, appended with the Mannich's base motifs at the nitrogen atom in its seven‐membered ring.