Reduction processes in the fast atom bombardment mass spectra of pyridinium salts. The effect of reduction potential and concentration

Abstract

The enhancement of the (C + 1)/C ratio in the fast atom bombardment mass spectra of seven pyridinium cations has been measured. No dependence of the enhancement on the cation reduction potential could be identified. The N-methyl pyridinium cation, which showed no enchancement under matrix-free conditions, exhibited an increase in the (C + l)/Cratio with decreasing concentration. This concentration dependence was eliminated when the bombardment energy was reduced from 9 to 5 keV. Possible mechanisms for the concentration dependence and the variation with bombardment energy are proposed.

A fast atom bombardment and matrix‐assisted laser desorption/ionization mass spectrometry study of doubly charged porphyrins

“…Although obvious differences in the experimental settings of FAB‐MS measurements and liquid‐phase electrochemical examinations are noticed, a comparison of the respective data is possible, as several studies are documented where remarkable parallels in the behavior of dyes, inorganic salts and porphyrins could be detected 14…”

Photophysical and Electrochemical Characterization of a Helical Viologen, N,N′-Dimethyl-5,10-diaza[5]helicene

“…MV 2+ undergoes more difficult (less extended π-system) but chemically and electrochemically reversible one-electron reductions in CH 3 CN at −0.50 and −0.92 V versus SCE . In contrast, the helquat, 4 2+ (Scheme ), is reduced to the radical cation at a potential (−0.87 V vs SCE) very close to that of N -methylpyridinium perchlorate (−0.81 V vs SCE), indicative of its dipyridinium rather than viologen core structure. In the case of MV 2+ the structures of the radical cation, MV •+ , and neutral, MV 0 , redox partners are well-established and are depicted in Scheme .…”