Reduction of cationic free-base meso-tris-N-methylpyridinium-4-yl porphyrins in positive mode electrospray ionization mass spectrometry.
Reductions involving more than one electron with formation of the M+ and [M+2H]+ ions were observed for electrosprayed meso-tris(N-methylpyridinium-4-yl)porphyrin iodides, MI3. These reductions were studied by using different solvents and flow rates. Formation of the [M+2H]+ ions occurred only for protic solvents and to a larger extent at lower flow rates. The type of the fourth substituent does not seem to affect the reduction processes. Formation of the two reduced species, M+ and [M+2H]+ ions, may occur through the participation of counter ion/solvent clusters. Reduction of multiply charged, non-metallated species with formation of [M+nH]+ ions (n > 1) was not observed before in positive mode electrospray mass spectrometry.
Ramos
Catarina I V
CI
Mass Spectrometry Laboratory, Department of Chemistry, University of Aveiro, Campus de Santiago, Aveiro, Portugal.
Santana Marques
M Graça
MG
Correia
A J Ferrer
AJ
Serra
Vanda Vaz
VV
Tomé
João P C
JP
Tomé
Augusto C
AC
Neves
M Graça P M S
MG
Cavaleiro
J A S
JA