selectfluor [1-(chloro methyl) -4-flouro -1,4-di azonia bicyclo[2,2,2] octane bis (tetraflouro-borate)] catalyzed the preparation of quinoxaline and 2,3-dihydo pyrazine derivatives through one -pot condensation of 1,2-di amines with 1,2-di carbonyls in solvent and under solvent- free conditions. this catalyst is commercially available, inexpensive, reusable, stable to air and moisture, and rela...

Hydrogen bond networks are key elements of protein structure and function but have been challenging to study within the complex protein environment. We have carried out in-depth interrogations of the proton transfer equilibrium within a hydrogen bond network formed to bound phenols in the active site of ketosteroid isomerase. We systematically varied the proton affinity of the phenol using diff...

In this study, two naturally occurred chromone derivatives obtained from Cassia nomame which are recently entered the literature, have been investigated computationally for their potential antiviral activity against SARS-CoV-2. first part of DFT calculations were performed on compounds. part, geometry optimizations, frequency analyses, molecular electrostatic map calculations, frontier orbital ...

Body's iterative force-field computer program has been used to calculate strain energies in cyclooctanone (I). 348 MHZ 1H NMR spectra of (I) have been investigated over the temperature range of 25° to -160°C. Two conformation processes affect the 1H NMR spectrum of (I). Iterative force-field calculations on the conformations and conformational interconversion paths of ...

Experimental parameters that influence the resolution of 1H-NMR phenol OH signals are critically evaluated with emphasis on the effects of pH, temperature and nature of the solvents. Extremely sharp peaks (Δν1/2≤2 Hz) can be obtained under optimized experimental conditions which allow the application of 1H-13C HMBC-NMR experiments to reveal long range coupling constants of hydroxyl protons and,...

The interaction of N,N0-bismesitylimidazolin-2-yl (IMes) with alcohols is discussed. NMR spectroscopy and X-ray crystallography were used to examine the influence of solvent and alcohol on this interaction. The stabilizing effect of these interactions may be used for the storage of nitrogen–heterocyclic carbenes (NHCs) since removal of the volatiles liberates the NHC. 2008 Elsevier Ltd. All rig...

Density functional theory dispersion corrected (DFT-D3)calculations and molecular dynamic (MD) simulation were applied to investigate the sensing ability of four types of receptors (RCs) composed of the ortho-phenylenediamine based bis-ureas for selective complexation with the anions such as Cl–, Br–, OAC–, PhCO2–, H2PO4– and HSO4– in the gas phase and DMSO. On the basis of the data obtained fr...

Tyrosine sulfation, a post-translational modification found on many chemokine receptors, typically increases receptor affinity for the chemokine ligand. A previous bioinformatics analysis suggested that a sulfotyrosine (sY)-binding site on the surface of the chemokine CXCL12 may be conserved throughout the chemokine family. However, the extent to which receptor tyrosine sulfation contributes to...