Corrole isomers: intrinsic gas-phase shapes via traveling wave ion mobility mass spectrometry and dissociation chemistries via tandem mass spectrometry

Abstract

PAPERCorrole and four of its isomers with subtle structural changes promoted by exchange of nitrogen and carbon atoms in the corrole ring have been studied by traveling wave ion mobility mass spectrometry and collision induced dissociation experiments. Significant differences in shapes and charge distributions for their protonated molecules were found to lead to contrasting gas phase mobilities, most particularly for corrorin, the most "confused" isomer. Accordingly, corrorin was predicted by B3LYP/6-31g(d,p) and collisional cross section calculations to display the most compact tri-dimensional structure, whereas NCC4 and corrole were found to be the most planar isomers. Better resolution between the corrole isomers was achieved using the more polarizable and massive CO 2 as the drift gas. Sequential losses of HF molecules were found to dominate the dissociation chemistry of the protonated molecules of these corrole isomers, but their unique structures caused contrasting labilities towards CID, whereas NCC4 showed a peculiar and structurally diagnostic loss of NH 3 , allowing its prompt differentiation from the other isomers.

Baseline resolution of isomers by traveling wave ion mobility mass spectrometry: investigating the effects of polarizable drift gases and ionic charge distribution

“…Utilizing more polar drift‐gases could potentially influence almost every application area where structural isomers are being investigated by TWIM‐MS and improved R p‐p is required. Studies have already demonstrated the beneficial results in using CO 2 as the TWIM drift‐gas . Based on our findings, the use of more polarizable drift‐gases improves R p‐p considerably for the isomers that differ in electrostatic surface potential, whereas isomeric pairs which electrostatic surface potential is only subtly different, R p‐p is not significantly affected.…”

Separation of glycosidic catiomers by TWIM‐MS using CO2 as a drift gas

“…In TWIM, ions are accumulated and periodically released into a stacked ring ion guide (T‐wave cell) where they drift under the action of a continuous train of transient voltage pulses applied to a pair of stacked ring electrodes that work as an ion mobility cell. We have used TWIM‐MS to separate and characterize geometrical isomers such as meta/para and cis/trans cationic ruthenates meso‐pyridylporphyrins, corrole isomers and isomeric disaccharides …”

“…[28,29] In TWIM, ions are accumulated and periodically released into a stacked ring ion guide (T-wave cell) where they drift under the action of a continuous train of transient voltage pulses applied to a pair of stacked ring electrodes that work as an ion mobility cell. We have used TWIM-MS to separate and characterize geometrical isomers such as meta/para and cis/trans cationic ruthenates meso-pyridylporphyrins, [30] corrole isomers [31] and isomeric disaccharides. [32] For glycosylated molecules, in which different and highly competitive coordinating sites are available for cation binding, several catiomers [3] with eventually similar cross sections and polarizabilities could be formed, and therefore, the determination of the site of cationization is particularly challenging.…”

Complementing the characterization of in vivo generated N‐glucuronic acid conjugates of stanozolol by collision cross section computation and analysis

“…He, N 2 , or CO 2 ), referred to as collision cross section (CCS), under the influence of a weak electronic field . Hence, IM provides specific information on structural conformation and is therefore currently used in several research areas and applications with a wide range from low molecular weight compounds up to mega Dalton‐sized biological structures including the rapid detection of chemicals in waste water and air, peptide and protein structure determination, pharmaceutical compound analysis, and studies on crude oil …”

“…[26,27] Hence, IM provides specific information on structural conformation and is therefore currently used in several research areas and applications with a wide range from low molecular weight compounds up to mega Dalton-sized biological structures including the rapid detection of chemicals in waste water and air, peptide and protein structure determination, pharmaceutical compound analysis, and studies on crude oil. [28][29][30][31][32][33][34][35][36][37] In the present study, travelling-wave ion mobility spectrometry (TWIMS) with nitrogen as drift gas interfaced to a quadrupoletime-of-flight (QqTOF) mass spectrometer was used to generate information on the conjugation site of stanozolol glucuronides observed in post-administration urine samples and authentic doping control specimens. Therefore, drift times of five different but structurally related known AAS glucuronides were determined, corresponding CCSs were calculated by means of modelling software tools (ORCA and MOBCAL) employing the data set of B3LYP/6-31G, [38][39][40][41][42] and a calibration curve for AAS glucuronides was created.…”