Multi-proton

Lately, electrospray ionisation technique (ESI-MS) which is compatible with RP-HPLC has been routinely used. This allows labile molecules to be studied intact. Sample molecules are simultaneously nebulised and ionised at atmospheric pressure in the presence of several thousand volts. The resulting ions can be multi-protonated (multiply charged) and relatively stable. This mode of ionisation has recently been used in the development of RP-HPLC coupled with positive ion ESI-MS and ion-trap MS protocols for the identification and... 

Hiemstra, T., J.C.M. De Wit, and W.H. Van Riemsdijk. 1989a. Multi proton adsorption modeling at the solid/solution interface of (hydr)oxides A new approach. II. Application to various important (hydr)oxides. J. Colloid Interf. Sci. 133 105-117. 

Since macrocyclic polyamines have a much greater charge density within the molecular skeletons in the multi-protonated state as compared to the linear polyamines, they should have an entropic advantage for the complexation of phosphates. On the basis of this advantage of macrocyclic polyamines over the corresponding acyclic polyamines, Kimura et aL reported that a macro-cyclic hexaamine 3 showed stronger affinity to AMP, ADP and ATP at pH 8.0... 

Studies of the kinetics and thermodynamics of proton transfer and hydride transfer reactions have led to a better fundamental understanding of the range of reactivity available, and how it is influenced by different metals and ligands. This information is also central to the rational development of molecular catalysts for oxidation of H2 and production of H2 described in Chapter 7, and in the broad context of other reactions pertinent to energy production and energy utilization that require control of multi-proton and multi-electron reactivity. 

For a typical organic solid, there exists a strongly dipolar-coupled multi-proton network, and the effect of MAS is quite different as compared to the case of the CSA interaction. This difference is explained in a classic paper by Maricq and Waugh [22]. The CSA is an example of an interaction where the anisotropic broad-... 

Rate Constants and the Kinetie Isotope Effeets in Multi-Proton Transfer Reactions A Case Study of CIONO2 + HCl HNO3 + Cl2 Reactions with Water Clusters with Canonical Variational Transition State Theory using a Direct Ab Initio Dynamics Approach... 

Rate Constants and the Kinetic Isotope Effects in Multi-Proton Transfer Reactions 57... 

One of the most important issues for multi-proton transfer reactions is their mechanism do they occur stepwise or concertedly Schowen highlighted this issue with four examples mutarotation of glucose with 2-pyridone tauto-merization of porphyrin molecules " alcohol-mediated double proton transfer in 7-azaindole and isomerization in 7-azaindole dimer. However, in the 7-azaindole dimer, the mechanism of the excited-state double proton transfer has not been fully resolved, even though careful experimental and quantum mechanical studies have been performed. " The excited-state reaction... 

The splitting of water into O2 and H2 is a major objective for the storage of solar energy into chemical fuels [107]. Two half-reactions are involved, namely, water oxidation, releasing O2, H, and e , and reduction of protons to H2. Water oxidation is a challenging process because of its multi-electron and multi-proton nature. 

Proton-coupled electron transfer (PCET) is a ubiquitous process in biology and chemistry and plays an essential role in multi-electron, multi-proton transfer processes of biological relevance, such as photosynthesis and respira-tion. The coupling between proton and electron motions stabilizes reaction intermediates, by preventing charge build-up during the accumulation of redox equivalents. The key role of PCET natural photosynthesis is probably the major contributor to this effect. 

While one-electron reduction of a proton and CO2 (eqs 1 and 6, respectively) and oxidation of water (eq 2) take place at very negative and positive potentials, respectively, the coupled multi-electron and multi-proton reactions occur at relatively modest potentials (eqs 3-5,7-12). 

Multi-protonic acids and multi-basic alkalis... 

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