Electrospray mass and tandem mass spectrometry of homologous and isomeric singly, doubly, triply and quadruply charged cationic ruthenated meso-(phenyl)m-(meta- and para-pyridyl)n (m + n = 4) macrocyclic porphyrin complexes
| Autor: | Marcos N. Eberlin, Ildemar Mayer, Koiti Araki, Henrique E. Toma, Fabio C. Gozzo, Fábio Monaro Engelmann, Daniela M. Tomazela |
|---|---|
| Rok vydání: | 2004 |
| Předmět: |
chemistry.chemical_classification
Spectrometry Mass Electrospray Ionization Porphyrins Electrospray ionization Cationic polymerization Analytical chemistry Mass spectrometry Tandem mass spectrometry Ruthenium Crystallography chemistry Isomerism Intramolecular force Cations Structural isomer Counterion Spectroscopy Gas-phase ion chemistry |
| Zdroj: | Journal of mass spectrometry : JMS. 39(10) |
| ISSN: | 1076-5174 |
| Popis: | Ten homologous or isomeric singly, doubly, triply and quadruply charged cationic macrocyclic complexes I-Va,b n+ (n = 1-4) formed by the coordination of [Ru(bipy) 2 Cl] + to the pyridyl N-atoms of a series of meso-(phenyl) m -(meta or para-pyridyl) n -porphyrins (m+n = 4) were transferred to the gas phase and structurally characterized by electrospray ionization (ESI) mass (MS) and tandem mass (MS/MS) spectrometry. Previously known to be stable in solution and in the solid state, I-Va, b n+ are found to constitute also a new class of stable, long-lived multiply charged gas-phase ions with spatially separated charge sites. Increasing intramolecular electrostatic repulsion from Ia, b + to IVa, b 3+ facilitates in-source and tandem collision-induced dissociation (CID). However, for the quadruply charged ions Va, b 4+ , electrostatic repulsion is alleviated mainly by ion pairing with the CF 3 SO 3 - counterion forming the salt clusters [Va,b/CF 3 SO 3 ] 3+ and [Va,b/(CF 3 SO 3 ) 2 ] 2+ with reduced charge states. Ion-pairing that yields [IVa,b/CF 3 SO 3 ] 2+ is also observed as a minor ESI process for the triply charged ions IVa, b 3+ . The gaseous ions I-Va, b n+ (n = 2, 3 or 4) dissociate by sequential 'charge partitioning' with the formation of two cationic fragments by the release of [Ru(bipy) 2 Cl] + . The meta (a) and para (b) isomers and the positional isomers II 2+ and III 2+ display nearly identical ESI-MS and ESI-MS/MS spectra. ESI-MS/MS of I-Va, b n+ shows that the Ru-py(P) is, intrinsically, the weakest bond since this bond breaks preferentially upon CID. |
| Databáze: | OpenAIRE |
| Externí odkaz: |
|
Plný text