Liquid secondary ion mass spectrometry of porphyrin dimers: reduction reactions and structural characterisation

New synthesised porphyrin dimers, with an amide or ester linkage between th e two porphyrin units, were studied using liquid secondary ion mass spectro metry (LSIMS). The formation of reduced species was observed for all the co mpounds and it was found that the extent of reduction is dependent on the m atrix used and on the structure of the porphyrin dimer. The main fragmentat ion pathways lead to monomer fragments resulting from cleavage of the amide or ester linkage between the two porphyrin units. The consistency of the F ragmentations for all the dimers studied leads to the proposal of a common designation for the fragment ions. LSIMS, in addition to molecular weight d etermination, can provide important structural information for this type of compound. Copyright (C) 2000 John Wiley & Sons, Ltd.