molecular structure, isomerism, conformational stability and intramolecular hydrogen bonding (ihb) of cis-enol forms of 1-(n-pyridyl)butane-1,3-diones (npbd) (n = 2, 3, or 4) have been investigated by means of density functional theory (dft) calculations. energy differences for all possible npbd cis-enol forms of isomers with respect to the most stable form of the corresponding isomer have been...

antioxidants are compounds which can prevent biological and chemical substances from oxidative damage by reactive oxygen species. flavonoids are the most important class of polyphenolic compounds that because of their antioxidant characters possess biological activities and pharmacological effects. chrysin-6-c-fucopyranoside and chrysin-3-malonyl-6-c-fucopyranoside are mono c-glycosyl derivativ...

The N-(2-benzoyl-phenyl) oxalyl derivatives are important models for studying of three-centered intramolecular hydrogen bonding in organic molecules. The quantum theoretical calculations for two crystal structures of N-(2-benzoyl-phenyl) oxalyl (compounds I and II) were performed by Density Functional Theory (B3LYP method and 6-311+G* basis set). From the optimized structures, geometric paramet...

the hydrolysis of sodium borohydride as a source of hydrogen gas is studied at different mole ratios of h+ to nabh4. the sulfonated porous carbon (spc) is used as a source of hydrogen ion and catalyst. it is found that the sulfonated porous carbon exhibits high activity for the hydrolysis of nabh4 to generate hydrogen gas at room temperature in comparison to amberlyst-15 and nafion-nr50. the ki...

A hypothesis is presented that electronic and vibrational resonant energy states are important in biochemical reactions due to their coupling to hydrogen transfer reactions. The hypothesis is based upon (1) the involvement of hydrogen in most biochemical reactions, (2) the unique abiity of hydrogen to act as an energy trap for resonant energy and (3) demonstrations of the coupling of resonant e...

A long-term hydrogen-based scenario of the global energy system is described in qualitative and quantitative terms here, illustrating the key role of hydrogen in a long-term transition toward a clean and sustainable energy future. In an affluent, low-population-growth, equity and sustainability-oriented B l-H2 world, hydrogen technologies experience substantial but plausible performance and cos...

in this study, the effect of the secondary structure of the protein on the acid strength of three structures of random (r), alpha helix (α) and beta sheet (b) were investigated theoretically. these structures are related to the cationic amino acids of histidine and lysine in the polypeptide chain of eight-glycine residue. computational methods at the hf, b3lyp, x3lyp and m05-2x levels in the ga...