Solution and gas phase evidence of anion binding through the secondary bonding interactions of a bidentate bis-antimony(iii) anion receptor

2018 ◽  
Vol 20 (1) ◽  
pp. 46-50 ◽  
Author(s):  
J. Qiu ◽  
B. Song ◽  
X. Li ◽  
A. F. Cozzolino
Keyword(s):  
Gas Phase ◽  
Anion Binding ◽  
Anion Receptor ◽  
Esi Ms ◽  
Nmr Titrations ◽  
Secondary Bonding

Solution and gas phase evidence of halide binding to a bis-antimony(iii) anion receptor is demonstrated through NMR titrations and ESI-MS.

Formation of polynuclear copper complexes of guanine-based nucleobases in the gas phase studied by ESI-MS

2013 ◽  
Vol 354-355 ◽  
pp. 303-311 ◽  
Author(s):  
Daniela Ascenzi ◽  
Pietro Franceschi ◽  
Graziano Guella ◽  
Paolo Tosi
Keyword(s):  
Gas Phase ◽  
Copper Complexes ◽  
Esi Ms

Study of the Gas-Phase Intramolecular Aryltrifluoromethylation of Phenyl(Trifluoromethyl)Iodonium by ESI-MS/MS

2013 ◽  
Vol 24 (5) ◽  
pp. 761-767 ◽  
Author(s):  
Hao-Yang Wang ◽  
Zhang Xiang ◽  
Guo-Sheng Liu ◽  
Yin-Long Guo
Keyword(s):  
Gas Phase ◽  
Esi Ms

Do electrospray mass spectra reflect the ligand binding state of proteins in solution?

2005 ◽  
Vol 83 (11) ◽  
pp. 1953-1960 ◽  
Author(s):  
Belal M Hossain ◽  
Douglas A Simmons ◽  
Lars Konermann
Keyword(s):  
Mass Spectrometry ◽  
Gas Phase ◽  
Protein Interactions ◽  
Noncovalent Complex ◽  
Deuterium Exchange ◽  
Solution Phase ◽  
Hydrogen Deuterium Exchange ◽  
Esi Ms ◽  
Protein Ions ◽  
Hydrogen Deuterium

Electrospray ionization (ESI) mass spectrometry (MS) has become a popular tool for monitoring ligand–protein and protein–protein interactions. Due to the "gentle" nature of the ionization process, it is often possible to transfer weakly bound complexes into the gas phase, thus making them amenable to MS detection. One problem with this technique is the potential occurrence of fragmentation events during ESI. Also, some analytes tend to cluster together during ionization, thus forming nonspecific gas-phase assemblies that do not represent solution-phase complexes. In this work, we implemented a hydrogen–deuterium exchange (HDX) approach that can reveal whether or not the free and (or) bound constituents of a complex observed in ESI-MS reflect the binding situation in solution. Proteins are subjected to ESI immediately following an isotopic labeling pulse; only ligand-free and ligand-bound protein ions that were formed directly from the corresponding solution-phase species showed different HDX levels. Using myoglobin as a model system, it is demonstrated that this approach can readily distinguish scenarios where the heme–protein interactions were disrupted in solution from those where dissociation of the complex occurred in the gas phase. Experiments on cytochrome c strongly suggest that dimeric protein ions observed in ESI-MS reflect aggregates that were formed in solution.Key words: electrospray mass spectrometry, ligand–protein interaction, noncovalent complex, hydrogen–deuterium exchange, protein folding.

scholarly journals Highly Efficient, Tripodal Ion-Pair Receptors for Switching Selectivity between Acetates and Sulfates Using Solid–Liquid and Liquid–Liquid Extractions

2020 ◽  
Vol 21 (24) ◽  
pp. 9465
Author(s):  
Marta Zaleskaya ◽  
Łukasz Dobrzycki ◽  
Jan Romański
Keyword(s):  
Binding Sites ◽  
Liquid Extraction ◽  
Ion Pair ◽  
Anion Binding ◽  
Binding Modes ◽  
Anion Receptor ◽  
X Ray ◽  
Liquid Liquid Extraction ◽  
Solid Liquid Extraction ◽  
Solid Liquid

A tripodal, squaramide-based ion-pair receptor 1 was synthesized in a modular fashion, and 1H NMR and UV-vis studies revealed its ability to interact more efficiently with anions with the assistance of cations. The reference tripodal anion receptor 2, lacking a crown ether unit, was found to lose the enhancement in anion binding induced by presence of cations. Besides the ability to bind anions in enhanced manner by the “single armed” ion-pair receptor 3, the lack of multiple and prearranged binding sites resulted in its much lower affinity towards anions than in the case of tripodal receptors. Unlike with receptors 2 or 3, the high affinity of 1 towards salts opens up the possibility of extracting extremely hydrophilic sulfate anions from aqueous to organic phase. The disparity in receptor 1 binding modes towards monovalent anions and divalent sulfates assures its selectivity towards sulfates over other lipophilic salts upon liquid–liquid extraction (LLE) and enables the Hofmeister bias to be overcome. By changing the extraction conditions from LLE to SLE (solid–liquid extraction), a switch of selectivity from sulfates to acetates was achieved. X-ray measurements support the ability of anion binding by cooperation of the arms of receptor 1 together with simultaneous binding of cations.

scholarly journals Characterization of a catalyst-based conversion technique to measure total particulate nitrogen and organic carbon and comparison to a particle mass measurement instrument

2018 ◽  
Vol 11 (5) ◽  
pp. 2749-2768 ◽  
Author(s):  
Chelsea E. Stockwell ◽  
Agnieszka Kupc ◽  
Bartłomiej Witkowski ◽  
Ranajit K. Talukdar ◽  
Yong Liu ◽  
...  
Keyword(s):  
Particle Size ◽  
Organic Carbon ◽  
Gas Phase ◽  
Mass Measurement ◽  
Single Component ◽  
Particle Mass ◽  
Negative Ion ◽  
Ionization Source ◽  
Particulate Nitrogen ◽  
Esi Ms

Abstract. The chemical composition of aerosol particles is a key aspect in determining their impact on the environment. For example, nitrogen-containing particles impact atmospheric chemistry, air quality, and ecological N deposition. Instruments that measure total reactive nitrogen (Nr = all nitrogen compounds except for N2 and N2O) focus on gas-phase nitrogen and very few studies directly discuss the instrument capacity to measure the mass of Nr-containing particles. Here, we investigate the mass quantification of particle-bound nitrogen using a custom Nr system that involves total conversion to nitric oxide (NO) across platinum and molybdenum catalysts followed by NO−O3 chemiluminescence detection. We evaluate the particle conversion of the Nr instrument by comparing to mass-derived concentrations of size-selected and counted ammonium sulfate ((NH4)2SO4), ammonium nitrate (NH4NO3), ammonium chloride (NH4Cl), sodium nitrate (NaNO3), and ammonium oxalate ((NH4)2C2O4) particles determined using instruments that measure particle number and size. These measurements demonstrate Nr-particle conversion across the Nr catalysts that is independent of particle size with 98 ± 10 % efficiency for 100–600 nm particle diameters. We also show efficient conversion of particle-phase organic carbon species to CO2 across the instrument's platinum catalyst followed by a nondispersive infrared (NDIR) CO2 detector. However, the application of this method to the atmosphere presents a challenge due to the small signal above background at high ambient levels of common gas-phase carbon compounds (e.g., CO2). We show the Nr system is an accurate particle mass measurement method and demonstrate its ability to calibrate particle mass measurement instrumentation using single-component, laboratory-generated, Nr-containing particles below 2.5 µm in size. In addition we show agreement with mass measurements of an independently calibrated online particle-into-liquid sampler directly coupled to the electrospray ionization source of a quadrupole mass spectrometer (PILS–ESI/MS) sampling in the negative-ion mode. We obtain excellent correlations (R2 = 0.99) of particle mass measured as Nr with PILS–ESI/MS measurements converted to the corresponding particle anion mass (e.g., nitrate, sulfate, and chloride). The Nr and PILS–ESI/MS are shown to agree to within ∼ 6 % for particle mass loadings of up to 120 µg m−3. Consideration of all the sources of error in the PILS–ESI/MS technique yields an overall uncertainty of ±20 % for these single-component particle streams. These results demonstrate the Nr system is a reliable direct particle mass measurement technique that differs from other particle instrument calibration techniques that rely on knowledge of particle size, shape, density, and refractive index.

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