Seven water-soluble, tetradentate bis(3-hydroxy-N-methyl-pyridin-2-one) (bis-Me-3,2-HOPO) ligands were synthesized that vary only in linker geometry and rigidity. Solution-phase thermodynamic measurements were conducted between pH 1.6 and pH 9.0 to determine the effects of these variations on proton and uranyl cation affinity. Proton affinity decreases by introduction of the solubilizing trieth...

The absorption spectra of a series of inhibitors bound at the active site of Delta(5)-3-ketosteroid isomerase from Pseudomonas putida were found to exhibit substantial variations in the contributions of the protonated and deprotonated forms. Systematic variation of the inhibitor solution pK(a) combined with a method of quantifying the contributions of each protonation state showed the oxyanion ...

The gas-phase structures of alkali-metal cationized glutamine are investigated by using both infrared multiple photon dissociation (IRMPD) action spectroscopy, utilizing light generated by a free electron laser, and theory. The IRMPD spectra contain many similarities that are most consistent with glutamine adopting nonzwitterionic forms in all ions, but differences in the spectra indicate that ...

The acid-sensing ion channels (ASICs) open in response to extracellular acidic pH, and individual subunits display differential sensitivity to protons and calcium. ASIC1a acts as a high affinity proton sensor, whereas ASIC2a requires substantially greater proton concentrations to activate. Using chimeras composed of ASIC1a and ASIC2a, we determined that two regions of the extracellular domain (...

The proton affinity of fluoroboroxine, FBO, is explored both experimentally and theoretically. Results of selected-ion flow tube measurements are reported for proton transfer reactions which place the proton affinity (PA) of FBO between those of ethylene and acetylene, PA(C2H4) > PA(FB0) > PA(C,H,), with PA(FB0) equal to 158 + 6kcalmoll’. FBOH’ is produced from the reaction of BF: with H,O and ...

A comprehensive conformational search and high-level composite ab initio computations provide benchmark proton affinities gas-phase basicities for glycine.

4,5-Dicyano-1H-[1,2,3]-Triazole (DCTz) exhibits a very low proton affinity. This makes it a possible water replacement for proton transport in high temperature polymer electrolyte membranes. A detailed investigation is carried out to define various physical properties as well as the proton transfer characteristics of DCTz. Thermogravimetric analysis showed that DCTz as well as DCTz salts are th...

We investigate the gas phase proton transfer reactivity of dianionic molybdenum oxysulfide clusters [Mo 2 O S 6 ] 2– and 5 in binary collisions an FT-ICR mass spectrometer combination with quantum chemical calculations. The reactions are probed a series acids increasing affinity, namely trifluoroacetic acid, difluoroacetic pyruvic acid formic acid. Proton followed by Coulomb explosion is observ...