Facile Synthesis of 5-Aryl-N-(pyrazin-2-yl)thiophene-2-carboxamides via Suzuki Cross-Coupling Reactions,Their Electronic and Nonlinear Optical Properties through DFT Calculations

Synthesis of 5-aryl-N-(pyrazin-2-yl)thiophene-2-carboxamides (4a–4n) by a Suzuki cross-coupling reaction of 5-bromo-N-(pyrazin-2-yl)thiophene-2-carboxamide (3) with various aryl/heteroaryl boronic acids/pinacol esters was observed in this article. The intermediate compound 3 was prepared by condensation of pyrazin-2-amine (1) with 5-bromothiophene-2-carboxylic acid (2) mediated by TiCl₄. The target pyrazine analogs (4a–4n) were confirmed by NMR and mass spectrometry. In DFT calculation of target molecules, several reactivity parameters like FMOs (E_HOMO, E_LUMO), HOMO–LUMO energy gap, electron affinity (A), ionization energy (I), electrophilicity index (ω), chemical softness (σ) and chemical hardness (η) were considered and discussed. Effect of various substituents was observed on values of the HOMO–LUMO energy gap and hyperpolarizability. The p-electronic delocalization extended over pyrazine, benzene and thiophene was examined in studying the NLO behavior. The chemical shifts of ¹H NMR of all the synthesized compounds 4a–4n were calculated and compared with the experimental values.     

Discovery of Potential Antiviral Compounds against Hendra Virus by Targeting Its Receptor-Binding Protein (G) Using Computational Approaches

Hendra virus (HeV) belongs to the paramyxoviridae family of viruses which is associated with the respiratory distress, neurological illness, and potential fatality of the affected individuals. So far, no competitive approved therapeutic substance is available for HeV. For that reason, the current research work was conducted to propose some novel compounds, by adopting a Computer Aided Drug Discovery approach, which could be used to combat HeV. The G attachment Glycoprotein (Ggp) of HeV was selected to achieve the primary objective of this study, as this protein makes the entry of HeV possible in the host cells. Briefly, a library of 6000 antiviral compounds was screened for potential drug-like properties, followed by the molecular docking of short-listed compounds with the Protein Data Bank (PDB) structure of Ggp. Docked complexes of top two hits, having maximum binding affinities with the active sites of Ggp, were further considered for molecular dynamic simulations of 200 ns to elucidate the results of molecular docking analysis. MD simulations and Molecular Mechanics Energies combined with the Generalized Born and Surface Area (MMGBSA) or Poisson–Boltzmann and Surface Area (MMPBSA) revealed that both docked complexes are stable in nature. Furthermore, the same methodology was used between lead compounds and HeV Ggp in complex with its functional receptor in human, Ephrin-B2. Surprisingly, no major differences were found in the results, which demonstrates that our identified compounds can also perform their action even when the Ggp is attached to the Ephrin-B2 ligand. Therefore, in light of all of these results, we strongly suggest that compounds (S)-5-(benzylcarbamoyl)-1-(2-(4-methyl-2-phenylpiperazin-1-yl)-2-oxoethyl)-6-oxo-3,6-dihydropyridin-1-ium-3-ide and 5-(cyclohexylcarbamoyl)-1-(2-((2-(3-fluorophenyl)-2-methylpropyl)amino)-2-oxoethyl)-6-oxo-3,6-dihydropyridin-1-ium-3-ide could be considered as potential therapeutic agents against HeV; however, further in vitro and in vivo experiments are required to validate this study.     

Multiple methoxy-substituted hole transporter for inverted perovskite solar cells

Inverted organic-inorganic hybrid perovskite solar cells(i-PSC)with low temperature processed interlayers and weak hysteresis behaviors have shown great potential for commercialization[1-5].However,their relatively lower power conversion efficiency(PCE)and inferior reproducibility than conventional PSCs limit further developments.These problems are largely determined by the hole transporting layer(HTL)and the quality of the upper perovskite film[6-8];in particular,the latter is considerably influenced by the surface property of the underlying HTL.     

Oligomer Sensor Nanoarchitectonics for “Turn-On” Fluorescence Detection of Cholesterol at the Nanomolar Level

Sensitive and rapid monitoring of cholesterol levels in the human body are highly desirable as they are directly related to the diagnosis of cardiovascular diseases. By using the nanoarchitectonic approach, a novel fluorescent conjugated oligofluorene (OFP-CD) functionalized with β-cyclodextrin (β-CD) was assembled for “Turn-On” fluorescence sensing of cholesterol. The appended β-CD units in OFP-CD enabled the forming of host-guest complexes with dabsyl chloride moieties in water, resulting in fluorescence quenching of the oligofluorene through intermolecular energy transfer. In the presence of cholesterol molecules, a more favorable host-guest complex with stoichiometry 1 cholesterol: 2 β-CD units was formed, replacing dabsyl chloride in β-CD’s cavities. This process resulted in fluorescence recovery of OFP-CD, owing to disruption of energy transfer. The potential of this nanoarchitectonic system for “Turn-On” sensing of cholesterol was extensively studied by fluorescence spectroscopy. The high selectivity of the sensor for cholesterol was demonstrated using biologically relevant interfering compounds, such as carbohydrates, amino acids, metal ions, and anions. The detection limit (LOD value) was as low as 68 nM, affirming the high sensitivity of the current system.     

Toward a modeling study of thermal conductivity of nanofluids using LSSVM strategy

Journal of Thermal Analysis and Calorimetry - In the present study, a comprehensive model based on least square support vector machine algorithm (LSSVM) was developed to estimate thermal...     

Pore-by-Pore Modelling,Validation and Prediction of Waterflooding in Oil-Wet Rocks Using Dynamic Synchrotron Data

We predict waterflood displacement on a pore-by-pore basis using pore network modelling. The pore structure is captured by a high-resolution image. We then use an energy balance applied to images of the displacement to assign an average contact angle, and then modify the local pore-scale contact angles in the model about this mean to match the observed displacement sequence. Two waterflooding experiments on oil-wet rocks are analysed where the displacement sequence was imaged using time-resolved synchrotron imaging. In both cases the capillary pressure in the model matches the experimentally obtained values derived from the measured interfacial curvature. We then predict relative permeability for the full saturation range. Using the optimised contact angles distributed randomly in space has little effect on the predicted capillary pressures and relative permeabilities, indicating that spatial correlation in wettability is not significant in these oil-wet samples. The calibrated model can be used to predict properties outside the range of conditions considered in the experiment.

     

Stereoselective synthesis of polyhydroxylated aminocyclohexanes

The stereoselective synthesis of a series of di- and tri-hydroxylated aminocyclohexane derivatives has been developed. A one-pot, two step tandem process involving an Overman rearrangement and a ring closing metathesis reaction has been utilised for the asymmetric synthesis of (1S)-1-(2',2',2'-trichloromethylcarbonylamino)cyclohexa-2-ene. Oxidation of this cyclohexene derivative was then studied leading to the preparation of two diol analogues in excellent stereoselectivity. (1S)-1-(2',2',2'-trichloromethylcarbonylamino)cyclohexa-2-ene was then converted to a novel allylic alcohol via a 4,5-dihydro-1,3-oxazole. Functionalisation of this allylic alcohol by Upjohn dihydroxylation conditions or by a directed epoxidation/hydrolysis sequence of reactions allowed the synthesis of two dihydroconduramines in excellent stereoselectivity. The stereochemical assignment of all compounds prepared was confirmed by NOE experiments or X-ray structure determination.     

Antioxidant activity of some lichen metabolites

Antioxidant activity of several classes of lichen metabolites were assessed in the in vitro superoxide radical (SOR), nitric oxide radical and 2,2-diphenyl-1-picrylhydrazil radical scavenging assays. The despsides sekikaic acid and lecanoric acid showed promising antioxidant activity in SOR assay with IC?? values of 82.0?±?0.3?μmol and 91.5?±?2.1?μmol, respectively, while the depsidone lobaric acid exhibited an IC?? value of 97.9?±?1.6?μmol, all relative to the standard, propyl gallate (IC???=?106.0?±?1.7?μmol). One of the most abundant mononuclear phenolic compounds, methyl-β-orcinol carboxylate was found to be a potent NO scavenger (IC???=?84.7?± 0.1?μmol), compared to the standard rutin (IC???=?86.8?±?1.9?μmol).