Relative Energetics of the Gas Phase Protomers of p-Aminobenzoic Acid and the Effect of Protonation Site on Fragmentation

2021 ◽  
Author(s):  
Maria Demireva ◽  
P. B. Armentrout
Keyword(s):  
Gas Phase ◽  
Aminobenzoic Acid ◽  
Protonation Site

Electronic Spectroscopy of Differential Mobility selected Prototropic Isomers of Protonated Para-Aminobenzoic Acid

2021 ◽  
Author(s):  
Neville Coughlan ◽  
Weiqiang Fu ◽  
Mircea Guna ◽  
Bradley Schneider ◽  
Yves Le Blanc ◽  
...  
Keyword(s):  
Gas Phase ◽  
Electronic Spectroscopy ◽  
Aprotic Solvents ◽  
Aminobenzoic Acid ◽  
Differential Mobility

Para-aminobenzoic acid (PABA) was electrosprayed from mixtures of protic and aprotic solvents, leading to formation of two prototropic isomers in the gas phase whose relative populations depended on the composition...

Structural features and protonation site of epibatidine in the gas phase: an investigation through infrared multiphoton dissociation spectroscopy and computational chemistry

2011 ◽  
Vol 13 (6) ◽  
pp. 2272-2277 ◽  
Author(s):  
Alexandre P. Atkinson ◽  
Aurélien Planchat ◽  
Jérôme Graton ◽  
Eric Renault ◽  
Gilles Grégoire ◽  
...  
Keyword(s):  
Computational Chemistry ◽  
Gas Phase ◽  
Structural Features ◽  
Infrared Multiphoton Dissociation ◽  
Protonation Site ◽  
Multiphoton Dissociation

Identification of the protonation site of gaseous triglycine: the cis-peptide bond conformation as the global minimum

2017 ◽  
Vol 19 (23) ◽  
pp. 15030-15038 ◽  
Author(s):  
Hongbao Li ◽  
Jun Jiang ◽  
Yi Luo
Keyword(s):  
Ab Initio ◽  
Gas Phase ◽  
Global Minimum ◽  
Peptide Bond ◽  
Protonation Site

Extensive ab initio investigations have been performed to characterize stable conformers of protonated triglycine (GGGH) in the gas phase.

scholarly journals Preferred protonation site of a series of sulfa drugs in the gas phase revealed by IR spectroscopy

2021 ◽  
Vol 75 (1) ◽  
Author(s):  
Thomas Uhlemann ◽  
Giel Berden ◽  
Jos Oomens
Keyword(s):  
Nitrogen Atom ◽  
Gas Phase ◽  
Mass Spectrometer ◽  
Bacterial Infections ◽  
Density Functional ◽  
Ion Cyclotron Resonance ◽  
Sulfa Drugs ◽  
Ir Radiation ◽  
Protonation Site ◽  
Formula Group

AbstractSulfa drugs are an important class of pharmaceuticals in the treatment of bacterial infections. The amido/imido tautomerism of these molecules in their neutral form has been widely discussed in the literature. Here, we study the protonation preferences of sulfa drugs upon electrospray ionization (ESI) using IR action spectroscopy of the ionized gas-phase molecules in a mass spectrometer. Our set of molecules includes sulfanilamide (SA), the progenitor of the family of sulfa drugs, and the actual, sulfonamide nitrogen substituted, sulfa drugs sulfamethoxazole (SMX), sulfisoxazole (SIX), sulfamethizole (SMZ), sulfathiazole (STZ), sulfapyridine (SP) and sulfaguanidine (SG). IR multiple photon dissociation (IRMPD) spectra were recorded for the protonated sulfa drugs using a Fourier transform ion cyclotron resonance mass spectrometer (FT-ICR-MS) and an optical parametric oscillator/amplifier (OPO/OPA) as well as the FELIX free electron laser (FEL) as IR sources. The OPO provides tunable IR radiation in the NH stretch region (3100–3700 cm$$^{-1}$$ - 1 ), while the FEL covers the fingerprint region (520–1750 cm$$^{-1}$$ - 1 ). Comparison of experimental IR spectra with spectra predicted using density functional theory allowed us to determine the gas-phase protonation site. For SA, the sulfonamide NH$$_2$$ 2 group was identified as the protonation site, which contrasts the situation in solution, where the anilinic NH$$_2$$ 2 group is protonated. For the derivative sulfa drugs, the favored protonation site is the nitrogen atom included in the heterocycle, except for SG, where protonation occurs at the sulfonamide nitrogen atom. The theoretical investigations show that the identified protonation isomers correspond to the lowest-energy gas-phase structures.

scholarly journals Combining density functional theory (DFT) and collision cross-section (CCS) calculations to analyze the gas-phase behaviour of small molecules and their protonation site isomers

The Analyst ◽  
2016 ◽  
Vol 141 (13) ◽  
pp. 4044-4054 ◽  
Author(s):  
Jasper Boschmans ◽  
Sam Jacobs ◽  
Jonathan P. Williams ◽  
Martin Palmer ◽  
Keith Richardson ◽  
...  
Keyword(s):  
Density Functional Theory ◽  
Small Molecules ◽  
Gas Phase ◽  
Cross Section ◽  
Computational Methods ◽  
Density Functional ◽  
Collision Cross Section ◽  
Phase Behaviour ◽  
Protonation Site ◽  
Functional Theory

Computational methods are employed to study the protomers in ESI-IM-MS.

scholarly journals Protonation site for anilines in aqueous media

2002 ◽  
Vol 67 (2) ◽  
pp. 111-113 ◽  
Author(s):  
Alexei Pankratov ◽  
Inna Uchaeva
Keyword(s):  
Nitrogen Atom ◽  
Aqueous Medium ◽  
Gaseous Phase ◽  
Aqueous Media ◽  
Aminobenzoic Acid ◽  
Amine Nitrogen Atom ◽  
Protonation Site ◽  
Amine Nitrogen ◽  
Aminobenzoic Acids ◽  
Phase Proceeds

By means of the PM3 method it has been shown that the protonation of 2-, 3 4-methoxyanilines, 4-methylthioaniline, 2-, 3-, 4-aminobenzoic acids, 2 3-, 4-nitroanilines in the gaseous phase proceeds via the amine nitrogen atom. The same result, attributed to the aqueous medium, was obtained for 4-methoxyaniline, 4-aminobenzoic acid and 4-nitroaniline.

Tracking the Structural Evolution of 4-Aminobenzoic Acid in the Transition from Solution to the Gas Phase

2020 ◽  
Vol 124 (11) ◽  
pp. 2081-2087 ◽  
Author(s):  
Michael J. Hebert ◽  
David H. Russell
Keyword(s):  
Gas Phase ◽  
Structural Evolution ◽  
Aminobenzoic Acid

scholarly journals Effects of ESI conditions on kinetic trapping of the solution-phase protonation isomer of p-aminobenzoic acid in the gas phase

2017 ◽  
Vol 418 ◽  
pp. 148-155 ◽  
Author(s):  
Amanda L. Patrick ◽  
Adam P. Cismesia ◽  
Larry F. Tesler ◽  
Nicolas C. Polfer
Keyword(s):  
Gas Phase ◽  
Solution Phase ◽  
Aminobenzoic Acid ◽  
Kinetic Trapping
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