Beam-induced reaction between meta-nitrobenzyl alcohol and dipyridocyanine dyes in liquid-secondary-ion mass spectrometry.

Analyses of cationic dipyridocyanine dyes by liquid-secondary-ion mass spectrometry in a liquid matrix of meta-nitrobenzyl alcohol (rnNBA) provide evidence for beam-induced addition reactions between the sample molecule (C) and the mNBA solvent. The ionic products of these addition reactions formally correspond to [C+mNBA-O2](+), Ic+mNBA-O2-H](+), and [C+mNBA-O2-2H](+). Initial loss of H from the adduct ion extends the conjugation of the adduct into the mNBA ring structure, whereas the final loss of hydrogen is thought to be promulgated by the formation of a benzylic radical stabilized through resonance with the π-electron system of the nitrobenzyl alcohol. Alternatively, two hydrogens may be lost from the alcohol functionality to form an aldehyde.