STRUCTURAL CHARACTERIZATION OF POLY(N-ALKYL-4-VINYLPYRIDINIUM) TRIFLATES USING PYROLYSIS TANDEM MASS-SPECTROMETRY

Desorption chemical ionization (DCI) and desorption electron ionizatio n (DEI) of homo- and co-polymers of N-alkyl-4-vinylpyridinium triflate s having ethyl, n-hexyl and n-dodecyl groups as N-alkyl substituents, produce mass spectra that display oligomeric ions. These positively ch arged ions are singly-charged and result from cleavage of the polymer into neutral oligomers and the loss of a single triflate anion per oli gomer. Analogous negatively charged ions, in which each neutral oligom er carries an extra triflate anion, are observed in the desorption che mical ionization mass spectra. Each oligomer within the available mass range is represented in the mass spectra. The formation of cluster io ns in which a single, multiply-charged cation is associated with a num ber of singly-charged anions, as observed for these ammonium polysalts , is unusual. Five major and three minor series of positively charged ions are observed in DCI and DEI methods of ionization. Ions in the di fferent series correspond either to cleavage at different bonds betwee n the constituent monomers or to hydrogen transfer in different direct ions. Unique and structurally diagnostic fragmentation processes are o bserved in tandem mass spectrometry (MS/MS) experiments performed usin g collision activated dissociation of mass-selected oligomeric ions.