A novel proton acceptor coupling reagent shows superiority to those described previously. The oxygen in the carbocation moiety confers more solubility to the reagent. Furthermore, it enhances coupling yields and decreases racemization, allowing the use of 1 equiv of base.

The buffer-mediated proton-transfer reactions of the fluorescent xanthenic derivative 9-[1-(2-Methyl-4-methoxyphenyl)]-6-hydroxy-3H-xanthen-3-one (TG-II) have been studied in different aqueous media. We have employed various buffers to investigate the influence of donor/acceptor systems with different anion and/or cation chemical constituents on the kinetic parameters of proton-transfer. The ki...

Six stable dimer models for 7-azaindole (including the classic C(2h) doubly hydrogen-bonded, coplanar, centrosymmetric dimer) are considered to be observable in adiabatic nozzle jet molecular beams. They are analyzed by hybrid density functional theory (DFT), the MP2 ab initio method for the ground electronic state, and the single-excitation configuration interaction (CIS) (over frozen ground s...

BACKGROUND Production or consumption of protons in growth medium during microbial metabolism plays an important role in determining the pH of the environment. Such pH changes resulting from microbial metabolism may influence the geochemical speciation of many elements in subsurface environments. Protons produced or consumed during microbial growth were measured by determining the amount of acid...

Enantioselective protonation is a common process in biosynthetic sequences. The decarboxylase and esterase enzymes that effect this valuable transformation are able to control both the steric environment around the proton acceptor (typically an enolate) and the proton donor (typically a thiol). Recently, several chemical methods to achieve enantioselective protonation have been developed by exp...

In the photosynthetic reaction center (RC) from Rhodobacter sphaeroides, the reduction of a bound quinone molecule Q(B) is coupled with proton uptake. When Asp-L213 is replaced by Asn, proton transfer is inhibited. Proton transfer was restored by two second-site revertant mutations, Arg-M233-->Cys and Arg-H177-->His. Kinetic effects of Cd(2+) on proton transfer showed that the entry point in re...

Bis(indolyl)methene displays high selectivity and sensitivity for aspartate and glutamate in water-containing medium based on the proton transfer signaling mode. The presence of acid can easily induce proton transfer to the basic H-bond acceptor moiety, which modulates the internal charge transfer state of the bis(indolyl)methene skeleton and gives rise to dramatic change in color. The detectio...

Water is the major component of all living cells, actually it composes 70% of our bodies. Its properties, very unusual when compared to other solvents, have made possible the life that we know. Water molecules spontaneously dissociate into a hydronium (H3O þ) and a hydroxide ion (OH). This autoprotolysis is a very rare event with the average lifetime of a single H2O molecule being ;14 h (Eigen,...

Raman activities and degrees of depolarization are reported for 14 complexes involving methanol, ethanol and water using the MP2/ aug-cc-pVDZ model. For ethanol both trans and gauche isomers are considered. The red-shifts of the OH stretching and the blue shifts of the bending sCO–OH mode were analyzed for the proton-donor molecules upon hydrogen bond. The shift of the mCO stretching mode of th...