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Alkali Metal Cation
The Experts below are selected from a list of 8484 Experts worldwide ranked by ideXlab platform
P B Armentrout – 1st expert on this subject based on the ideXlab platform
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Alkali Metal Cation interactions with 15 crown 5 in the gas phase revisited
Journal of Physical Chemistry A, 2014Co-Authors: P B Armentrout, C.a. Austin, M T RodgersAbstract:Quantitative interactions of the Alkali Metal Cations with the cyclic 15-crown-5 polyether ligand (15C5) are studied. In this work, Rb+(15C5) and Cs+(15C5) complexes are formed using electrospray ionization and studied using threshold collision-induced dissociation with xenon in a guided ion beam tandem mass spectrometer. The energy-dependent cross sections thus obtained are interpreted to yield bond dissociation energies (BDEs) using an analysis that includes consideration of unimolecular decay rates, internal energy of the reactant ions, and multiple ion–neutral collisions. 0 K BDEs of 175.0 ± 9.7 and 159.4 ± 9.6 kJ/mol, respectively, are determined and exceed those previously measured [J. Am. Chem. Soc. 1999, 121, 417−423] by 68 and 57 kJ/mol, respectively, consistent with the hypothesis proposed there that excited conformers had been studied. Because the analysis techniques have advanced since this early study, we also reanalyze the published data for the Na+(15C5) and K+(15C5) systems to ensure a sel…
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Alkali Metal Cation interactions with 12 crown 4 in the gas phase revisited
International Journal of Mass Spectrometry, 2012Co-Authors: P B Armentrout, C.a. Austin, M T RodgersAbstract:Abstract Quantitative interactions of Alkali Metal Cations with the cyclic 12-crown-4 polyether ligand (12C4) are studied. Experimentally, Rb + (12C4) and Cs + (12C4) complexes are formed using electrospray ionization and their bond dissociation energies (BDEs) determined using threshold collision-induced dissociation of these complexes with xenon in a guided ion beam tandem mass spectrometer. The energy-dependent cross sections thus obtained are interpreted using an analysis that includes consideration of unimolecular decay rates, internal energy of the reactant ions, and multiple ion-neutral collisions. 0 K BDEs of 151.5 ± 9.7 and 137.0 ± 8.7 kJ/mol, respectively, are determined and exceed those previously measured by 60 and 54 kJ/mol, respectively, consistent with the hypothesis proposed there that excited conformers had been studied. In order to provide comparable thermochemical results for the Na + (12C4) and K + (12C4) systems, the published data for these systems are reinterpreted using the same analysis techniques, which have advanced since the original data were acquired. Revised BDEs for these systems are obtained as 243.9 ± 12.6 and 182.0 ± 17.3 kJ/mol, respectively, which are within experimental uncertainty of the previously reported values. In addition, quantum chemical calculations are conducted at the B3LYP and MP2(full) levels of theory with geometries and zero point energies calculated at the B3LYP level using both HW*/6-311+G(2d,2p) and def2-TZVPPD basis sets. The theoretical results are in reasonable agreement with experiment, with B3LYP/def2-TZVPPD values being in particularly good agreement. Computations also allow the potential energy surfaces for dissociation of the M + (12C4) complexes to be elucidated. These are used to help explain why the previous studies formed excited conformers of Rb + (12C4) and Cs + (12C4) but apparently not of Na + (12C4) and K + (12C4).
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thermochemistry of Alkali Metal Cation interactions with histidine influence of the side chain
Journal of Physical Chemistry A, 2012Co-Authors: P B Armentrout, Y. Chen, Murat Citir, M T RodgersAbstract:The interactions of Alkali Metal Cations (M+ = Na+, K+, Rb+, Cs+) with the amino acid histidine (His) are examined in detail. Experimentally, bond energies are determined using threshold collision-induced dissociation of the M+(His) complexes with xenon in a guided ion beam tandem mass spectrometer. Analyses of the energy dependent cross sections provide 0 K bond energies of 2.31 ± 0.11, 1.70 ± 0.08, 1.42 ± 0.06, and 1.22 ± 0.06 eV for complexes of His with Na+, K+, Rb+, and Cs+, respectively. All bond dissociation energy (BDE) determinations include consideration of unimolecular decay rates, internal energy of reactant ions, and multiple ion-neutral collisions. These experimental results are compared to values obtained from quantum chemical calculations conducted previously at the MP2(full)/6-311+G(2d,2p), B3LYP/6-311+G(2d,2p), and B3P86/6-311+G(2d,2p) levels with geometries and zero point energies calculated at the B3LYP/6-311+G(d,p) level where Rb and Cs use the Hay–Wadt effective core potential and ba…
Richard A Bartsch – 2nd expert on this subject based on the ideXlab platform
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side arm participation in lariat ether carboxylate Alkali Metal Cation complexes in solution
Tetrahedron, 2005Co-Authors: Lokman Torun, Thomas W Robison, Jan Krzykawski, David W Purkiss, Richard A BartschAbstract:Abstract Lariat ether carboxylic acids of structure CECH2OCH2C6H4–2-CO2H with crown ether (CE) ring sizes of 12-crown-4, 15-crown-5 and 18-crown-6 are prepared and converted into Alkali Metal–lariat ether carboxylate complexes. Absorptions for the diastereotopic benzylic protons in the 1H NMR spectra of the complexes in CDCl3 are utilized to probe the extent of side arm interaction with the crown ether-complexed Metal ion as a function of the crown ether ring size and identity of the Alkali Metal Cation.
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Evaluation of Alkali and Alkaline earth Metal Cation selectivities of lariat ether amides by electrospray ionization mass spectrometry
Journal of the American Society for Mass Spectrometry, 2003Co-Authors: Sheldon M. Williams, Jennifer S Brodbelt, Richard A BartschAbstract:Lariat ethers with pendant amide groups have shown promise as new ion sensors because of their selectivity towards particular Metal ions. In this study we report Alkali and Alkaline earth Metal binding selectivities of dibenzo-16-crown-5 and fifteen dibenzo-16-crown-5 lariat ether amides (LEAs) as determined by electrospray ionization mass spectrometry (ESI-MS). Additionally, the influence of the acid/base nature of the solution on Metal Cation selectivity is investigated. The validity of using ESI-MS for determination of selectivities is established by analogous experiments using hosts with known binding constants for the same Metal Cations and solvent systems. Collisionally activated dissociation (CAD) is used to evaluate the influence of the Alkali Metal Cation binding on the fragmentation of the LEAs.
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Structure–Alkali Metal Cation complexation relationships for macrocyclic PNP-lariat ether ligands
Journal of The Chemical Society-perkin Transactions 1, 2002Co-Authors: Richard A Bartsch, Sangki Chun, Nazar S. A. Elkarim, Krystyna Brandt, Iwona Porwolik-czomperlik, Mariola Siwy, Dariusz Lach, Jerzy SilberringAbstract:Water-insoluble, mono- and diarmed PNP-lariat ethers containing various aryloxy and regioisomerically-positioned binaphthylylenedioxy substituents linked to the phosphorus atoms of the cyclophosphazene ring via oxygen atoms are synthesized by regioselective, sodium ion-assisted arylolysis of tetrachloro-16-PNP-6 crown ether 1. Heterogeneously-substituted, mixed aryloxy-amino PNP-lariat ethers and bis-lariat ethers with two different substituents linked to the PNP-macrocycle via an oxygen and a nitrogen atom are prepared by stepwise arylolysis and aminolysis reactions of 1. The Alkali–Metal Cation complexation behavior of the PNP-lariat ethers is evaluated in solvent polymeric membrane electrodes. The PNP-lariat and bis-lariat ethers exhibit pronounced selectivity for large Alkali Metal Cations (Rb+ and Cs+) over small ones (Li+
and Na+). The selectivity is influenced by the configuration of the crown ether ring and the number of oxygen donor atoms in the ligand. For some PNP-lariat ethers, evidence for formation of 2 : 1 (ligand–Metal ion) complexes with Rb+ and Cs+ is provided by ESI-MS.
Hana Sychrová – 3rd expert on this subject based on the ideXlab platform
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fluconazole affects the Alkali Metal Cation homeostasis and susceptibility to Cationic toxic compounds of candida glabrata
Microbiology, 2014Co-Authors: Hana Elicharova, Hana SychrováAbstract:Candida glabrata is a salt-tolerant and fluconazole (FLC)-resistant yeast species. Here, we analyse the contribution of plasma-membrane Alkali–Metal–Cation exporters, a Cation/proton antiporter and a Cation ATPase to Cation homeostasis and the maintenance of membrane potential (ΔΨ). Using a series of single and double mutants lacking CNH1 and/or ENA1 genes we show that the inability to export potassium and toxic Alkali–Metal Cations leads to a slight hyperpolarization of the plasma membrane of C. glabrata cells; this hyperpolarization drives more Cations into the cells and affects Cation homeostasis. Surprisingly, a much higher hyperpolarization of C. glabrata plasma membrane was produced by incubating cells with subinhibitory concentrations of FLC. FLC treatment resulted in a substantially increased sensitivity of cells to various Cationic drugs and toxic Cations that are driven into the cell by negative-inside plasma-membrane potential. The effect of the combination of FLC plus Cationic drug treatment was enhanced by the malfunction of Alkali–Metal–Cation transporters that contribute to the regulation of membrane potential and Cation homeostasis. In summary, we show that the combination of subinhibitory concentrations of FLC and Cationic drugs strongly affects the growth of C. glabrata cells.
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yeast 14 3 3 proteins participate in the regulation of cell Cation homeostasis via interaction with nha1 Alkali Metal Cation proton antiporter
Biochimica et Biophysica Acta, 2012Co-Authors: Jaromir Zahradka, Paul G H Van Heusden, Hana SychrováAbstract:Abstract Background In yeast, 14-3-3 proteins bind to hundreds of phosphorylated proteins and play a role in the regulation of many processes including tolerance to NaCl. However, the mechanism of 14-3-3 involvement in the cell answer to salt or osmotic stresses is weakly understood. Methods We studied the role of the Saccharomyces cerevisiae 14-3-3 homologs Bmh1 and Bmh2 in the regulation of Alkali–Metal–Cation homeostasis using the genetic-interaction approach. Obtained results were confirmed with the Bimolecular-Fluorescence-Complementation method. Results Deletion of BMH1, encoding the major 14-3-3 isoform, resulted in an increased sensitivity to Na+, Li+ and K+ and to Cationic drugs but did not affect membrane potential. This bmh1Δ phenotype was complemented by overexpression of BMH2. Testing the genetic interaction between BMH genes and genes encoding plasma-membrane Cation transporters revealed, that 14-3-3 proteins neither interact with the potassium uptake systems, nor with the potassium-specific channel nor with the Na+(K+)-ATPases. Instead, a genetic interaction was identified between BMH1 and NHA1 which encodes an Na+(K+)/H+ antiporter. In addition, a physical interaction between 14-3-3 proteins and the Nha1 antiporter was shown. This interaction does not depend on the phosphorylation of the Nha1 antiporter by Hog1 kinase. Our results uncovered a previously unknown interaction partner of yeast 14-3-3 proteins and provided evidence for the previously hypothesized involvement of Bmh proteins in yeast salt tolerance. General significance Our results showed for the first time that the yeast 14-3-3 proteins and an Alkali–Metal–Cation efflux system interact and that this interaction enhances the cell survival upon salt stress.
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Alkali Metal Cation influx and efflux systems in nonconventional yeast species
Fems Microbiology Letters, 2011Co-Authors: Jose Ramos, Joaquin Arino, Hana SychrováAbstract:To maintain optimal intracellular concentrations of Alkali–Metal–Cations, yeast cells use a series of influx and efflux systems. Nonconventional yeast species have at least three different types of efficient transporters that ensure potassium uptake and accumulation in cells. Most of them have Trk uniporters and Hak K+–H+ symporters and a few yeast species also have the rare K+ (Na+)-uptake ATPase Acu. To eliminate surplus potassium or toxic sodium Cations, various yeast species use highly conserved Nha Na+ (K+)/H+ antiporters and Na+ (K+)-efflux Ena ATPases. The potassium-specific yeast Tok1 channel is also highly conserved among various yeast species and its activity is important for the regulation of plasma membrane potential.