Meticulous assessment of natural compounds from NPASS database for identifying analogue of GRL0617, the only known inhibitor for SARS-CoV2 papain-like protease (PLpro) using rigorous computational workflow

Molecular Diversity - The latest global outbreak of 2019 respiratory coronavirus disease (COVID-19) is triggered by the inception of novel coronavirus SARS-CoV2. If recent events are of any...     

Cu(I)‐Catalyzed Efficient Synthesis of 2′‐Triazolo‐nucleoside Conjugates

A small library of thirty‐two 2′‐triazolyl uridine and 2′‐triazolyl‐5‐methyluridine has been synthesized by Cu(I)‐catalyzed condensation of 2′‐azido‐2′‐deoxyuridine and 2′‐azido‐2′‐deoxy‐5‐methyluridine with different alkynes and aryl propargyl ethers in almost quantitative yields. Triazolo‐nucleoside conjugates, which can be evaluated for different biological activity for suitable drug development, were unambiguously identified on the basis of ¹H NMR, ¹³C NMR, IR, and HRMS data analysis. These compounds have been synthesized for the first time and have not been reported in the literature earlier.     

Synthesis and Study of Polymeric Ultraviolet Absorbers. II

Polymeric UV absorbers have been prepared by free-radical solution copolymerization at 75°C of methyl methacrylate and 2-hydroxy-4-methacryloyloxybenzophenone monomers at low conversion (around 10%). The composition of the copolymers was determined by UV, IR, and NMR studies. The molecular weight was estimated by GPC. The reactivity ratios were determined by several methods. Viscosity was used to study the effect of copolymer composition and solvents. The copolymers were also analyzed by TGA and DSC, and DSC was used to study the effect of copolymer composition on T_g.     

Comparison of flow and batch polymerization processes for production of vinyl ether terpolymers for use in the delivery of siRNA

Synthetic polymers represent a modifiable class of materials that can serve as adjuvants to address challenges in numerous biomedical and medicinal chemistry applications including the delivery of siRNA. Polymer‐based therapeutics offer unique challenges in both synthesis and characterization as compared to small molecule therapeutics. The ability to control the structure of the polymer is critical in creating a therapeutic. Reported herein, are batch and flow polymerization processes to produce amphiphilic terpolymers through a Lewis acid BF₃OEt₂‐catalyzed polymerization. These processes focus on controlling reaction variables, which affect polymer structure in this rapid, exothermic, nonliving cationic polymerization. In addition to analytical characterization of the polymers, the in vivo activity of the polymer‐siRNA conjugates is also highlighted—demonstrating that the method of synthesis does affect the in vivo activity of the resulting polymer conjugate. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014 , 52, 1119–1129     

Probing Relaxation Dynamics in Five-Coordinate Dysprosium Single-Molecule Magnets

A new family of five-coordinate lanthanide single-molecule magnets (Ln SMMs) [Dy(Mes*O)₂(THF)₂X] (Mes*=2,4,6-tri-tert-butylphenyl; X=Cl, 1 ; Br, 2 ; I, 3 ) is reported with energy barriers to magnetic reversal >1200 K. The five-coordinate Dy^III ions have distorted square pyramidal geometries, with halide anions on the apex, and two Mes*O ligands mutually trans- to each other, and the two THF molecules forming the second trans- pair. These geometrical features lead to a large magnetic anisotropy in these complexes along the trans-Mes*O direction. QTM and Raman relaxation times are enhanced by varying the apex halide from Cl to Br to I, or by dilution in a diamagnetic yttrium analogue.     

Structural characterization of microwave-synthesized zinc-substituted cobalt ferrite nanoparticles

Microwave combustion technique modified by post treatment procedure is used to synthesize single-phase spinel ferrites of cobalt, zinc, and substituted magnetic nanoparticles of typical size 390 Å. The post treatment does not alter the crystal structure but increases the crystallinity. This is confirmed by powder x-ray diffraction and Fourier Transform Infrared (FTIR) studies. Citric acid is used as a fuel. The fresh synthesized sample shows an impurity phase in x-ray and in FTIR. This is due to the unreacted citrate molecule adsorbed on the particle surface. It is shown that by treating the sample with 0.1 M HCl, we can eliminate the impurity phase, and one can obtain a pure single phase. The magnetization at 8 kOe increases by nearly 8% after the removal of impurity. In order to remove surface adsorbed OH^? ion, samples are treated with NaCl and heated to 200°C for four hours. The XRD result indicates that after the treatment neither the crystallite size nor the distribution changes, but it removes OH^? ion. This is also confirmed by FTIR analysis. Thus, this modified technique can be used to synthesize pure nanocrystalline samples of spinel ferrites.     

Catalytic and Asymmetric Fluorolactonisations of Carboxylic Acids through Anion Phase Transfer

Catalytic fluorolactonisations of aromatic carboxylic acids have been developed. The reactions proceed under mild conditions using the commercially available reagent Selectfluor. A weak phase transfer of the reagent mediated by Na₂CO₃ allows the reaction to be conducted in non‐polar solvents. Furthermore, by the use of a catalytic amount of (DHQ)₂PHAL (hydroquinine 1,4‐phthalazinediyl diether), the first asymmetric fluorolactonisation has been achieved. The corresponding isobenzofuran core can be found in many biologically active molecules.     

Convenient Synthesis of Nucleoside‐5′‐Diphosphates from the Corresponding Ribonucleoside‐5′‐phosphoroimidazole

The reaction of ribonucleoside‐5′‐phosphoroimidazolide with a tributylammonium orthophosphate in anhydrous dimethylformamide at room temperature provides a general method for the synthesis of nucleoside‐5′‐diphosphates. The novelty of the approach is to use the triethylammonium salt of 5′‐monophosphate nucleoside derivative prior to the imidazolate reaction with imidazole, triphenylphosphine, and 2,2′‐dithiodipyridine. Deprotection, followed by displacement of the imidazole moiety using tributylammonium orthophosphate and a catalytic amount of zinc chloride in dimethylformamide gave the desired 5′‐diphosphate products. The triethyl ammonium salt of 5′‐diphosphate nucleosides was purified by flash chromatography using DEAE (diethylaminoethyl weak anion exchange resin) Sepharosa fast flow packed in an XK 50/60 column on an Akta FPLC (Fast Protein Liquid Chromatography). Synthesis procedures are reported for adenosine‐5′‐diphosphate, uridine‐5′‐diphosphate, cytidine‐5′‐diphosphate, and guanosine‐5′‐diphosphate. Yields for the displacement reactions ranged from 95 to 97%. Thus, this method offers the advantages of shorter reaction time, greater product yield, and a more cost‐effective synthetic route.