A flow battery employing H 2 as the fuel and one or more of highly soluble halate salts (such as 50 % w/w LiBrO 3 aq.) as the oxidant presents a viable opportunity as a power source for fully electric vehicles which meets the specific energy, specific power, energy efficiency, cost, safety, and refill time requirements. We further disclose a process of regeneration of the fuel and the oxidant from the discharged halide salt and water using electric (or solar) energy as the only input and generating no chemical waste. The cycle of discharge and regeneration takes advantage of pH-driven comproportionation and disproportionation reactions, respectively, and of pH manipulation using an orthogonal ion migration across laminar flow (OIMALF™) reactor.

In this work, we regiospecifically generate and compare the gas-phase properties of two isomeric forms of tryptophan radical cations-a distonic indolyl N-radical (H3N(+) - TrpN(•)) and a canonical aromatic π (Trp(•+)) radical cation. The distonic radical cation was generated by nitrosylating the indole nitrogen of tryptophan in solution followed by collision-induced dissociation (CID) of the resulting protonated N-nitroso tryptophan. The π-radical cation was produced via CID of the ternary [Cu(II)(terpy)(Trp)](•2+) complex. CID spectra of the two isomeric species were found to be very different, suggesting no interconversion between the isomers. In gas-phase ion-molecule reactions, the distonic radical cation was unreactive towards n-propylsulfide, whereas the π radical cation reacted by hydrogen atom abstraction. DFT calculations revealed that the distonic indolyl radical cation is about 82 kJ/mol higher in energy than the π radical cation of tryptophan. The low reactivity of the distonic nitrogen radical cation was explained by spin delocalization of the radical over the aromatic ring and the remote, localized charge (at the amino nitrogen). The lack of interconversion between the isomers under both trapping and CID conditions was explained by the high rearrangement barrier of ca.137 kJ/mol. Finally, the two isomers were characterized by infrared multiple-photon dissociation (IRMPD) spectroscopy in the ~1000-1800 cm(-1) region. It was found that some of the main experimental IR features overlap between the two species, making their distinction by IRMPD spectroscopy in this region problematic. In addition, DFT theoretical calculations showed that the IR spectra are strongly conformation-dependent.

Gas-phase ion-molecule reactions of four boron-containing neutrals were explored as a means for differentiation between isobaric phospho- and sulfocarbohydrates. Phosphorylation and sulfation impose an addition of 80 Da to the molecular mass, so for low-resolution mass spectrometers compounds that have such modifications will appear at the same nominal mass-to-charge (m/z) ratio. However, the ions of these isobaric species behave differently in ion-molecule reactions. All four evaluated neutral molecules [trimethyl borate (TMB), triethyl borate (TEB), diethylmethoxyborane (DEMB) and diisopropoxymethylborane (DIPMB)] proved to be reactive towards phosphorylated sugars and unreactive towards sulfated carbohydrates. In addition, TMB and TEB were found suitable for distinguishing positional isomers of phosphorylated carbohydrates, while reactions with DEMB and DIPMB were successful in differentiating phosphorylated, sulfated and unmodified deprotonated sugars. Similar reactions in the positive ion mode (alkali cationised) were found to be less conclusive.

Two types of radical cations of tryptophan-the p-radical cation and the protonated tryptophan-N radical-have been studied in dipeptides AW and WA. The p-radical cation produced by removal of an electron during collision-induced dissociation of a ternary Cu(II) complex was only observed for the AW peptide. In the case of WA, only the ion corresponding to the loss of ammonia, [WA-NH 3 ] þ , was observed from the copper complex. Both protonated tryptophan-N radicals were produced by N-nitrosylation of the neutral peptides followed by transfer to the gas phase via electrospray ionization and subsequent collision-induced dissociation. The regiospecifically formed N species were characterized by infrared multiple-photon dissociation spectroscopy which revealed that the WA tryptophan-N radical remains the nitrogen radical, while the AW nitrogen radical rearranges into the p-radical cation. These findings are supported by the density functional theory calculations that suggest a relatively high barrier for the radical rearrangement (N to p) in WA (156.3 kJ mol À1) and a very low barrier in AW (6.1 kJ mol À1). The facile hydrogen atom migration in the AW system is also supported by the collision-induced dissociation of the tryptophan-N radical species that produces fragments characteristic of the tryptophan p-radical cation. Gas-phase ion-molecule reactions with n-propyl thiol have also been used to differentiate between the p-radical cations (react by hydrogen abstraction) and the tryptophan-N species (unreactive) of AW.

a b s t r a c tThe effects of hydrogen bonding and spin density at the oxygen atom on the gas-phase reactivity of phenoxyl radicals were investigated experimentally and theoretically in model systems and the dipeptide LysTyr. Gas-phase ion-molecule reactions were carried out between radical cations of several aromatic nitrogen bases with the neutrals nitric oxide and n-propyl thiol. Reactivity of radical cations 4-6 correlated with the spin density. The possibility of hydrogen bonding was explored in compounds which allowed four-, five-, and six-membered ring to be formed between the protonated nitrogen and the phenoxyl oxygen, while possessing similar spin density at the oxygen atom. The N + -H· · ·O • bond length was calculated to decrease in the series (1-3), consistent with the theoretical calculations finding weak hydrogen bonding in 2 and strong hydrogen bonding in 3. This coincided with the decrease in reaction rates of 1-3 with both nitric oxide and n-propyl thiol. DFT calculations found that the lowest energy structure of the distonic radical cation of the dipeptide [LysTyr(O • )] + has a short hydrogen bond between the protonated Lys side chain and the phenoxyl oxygen, 1.70Å, which is consistent with its low reactivity.