The ligand L(1), which contains a chelating 2-(2-pyridyl)benzimidazole (PB) unit with a pendant anthacenyl group An connected via a methylene spacer, (L(1) = PB-An), was used to prepare the 8-coordinate lanthanide(III) complexes [Ln(hfac)(3)(L(1))] (Ln = Nd, Gd, Er, Yb) which have been structurally characterised and all have a square antiprismatic N(2)O(6) coordination geometry. Whereas free L(...

Reaction energetics of the double (2H+/2e-), i.e., the first 1H+/1e- (catechol→ phenoxyl radical) and the second 1H+/1e- (phenoxyl radical→ quinone) free radical scavenging mechanisms of quercetin and its six colonic catecholic metabolites (caffeic acid, hydrocaffeic acid, homoprotocatechuic acid, protocatechuic acid, 4-methylcatechol, and catechol) were computationally studied using density fu...

Enzymes in biology's energy chains operate with low energy input distributed through multiple electron transfer steps between protein active sites. The general challenge of biological design is how to lower the activation barrier without sacrificing a large negative reaction free energy. We show that this goal is achieved through a large polarizability of the active site. It is polarized by all...

A general approach to calculate the diabatic surfaces for electron-transfer reactions is presented, based on first-principles molecular dynamics of the active centers and their surrounding medium. The excitation energy corresponding to the transfer of an electron at any given ionic configuration (the Marcus energy gap) is accurately assessed within ground-state density-functional theory via a n...

The sub-nanosecond structural dynamics of reduced and oxidized cytochrome c were characterized. Dynamic properties of the protein backbone measured by amide (15)N relaxation and side chains measured by the deuterium relaxation of methyl groups change little upon change in the redox state. These results imply that the solvent reorganization energy associated with electron transfer is small, cons...

Room temperature ionic liquids, which have unique properties such as a relatively wide electrochemical stability window and negligible vapor pressure, are promising candidates as electrolytes for developing lithium−air batteries with enhanced performance. The local current density, a crucial parameter in determining the performance of lithium−air batteries, is directly proportional to the rate ...

The reaction 3-hydroxybutyrate (3-OH-butyrate) + 2 cytochrome c + ~ + 2 ADP + 2 Pi acetoacetate + 2 cytochrome e+’ + 2 ATP was used to study the energy relationships of electron transfer in the forward and reverse directions in suspensions of isolated rat liver mitochondria. Reduction of cytochrome c was monitored continuously at 550-540 nm while aliquots were taken to measure transmembrane pH ...

The arithmetic mean roughness, Ra, values were determined by scanning electron microscopic technique of different core models (furazolidone, nitrofurantoin and acetyl salicylic acid), coated by HPMC film forming solution containing 10 wt% of various molecular weight PEGs. The results showed that both plasticizer molecular weight and core surface free energy could have a significant influence on...

Femtosecond transient absorption spectroscopy in the range of 500-1040 nm was used to study electron transfer at 5 K in reaction centers of Rhodobacter sphaeroides R26 in which the bacteriopheophytins (BPhe) were replaced by plant pheophytin a (Phe). Primary charge separation took place with a time constant of 1.6 ps, similar to that found in native RCs. Spectral changes around 1020 nm indicate...