Takudrei

108
Fragmentation reactions of singly and doubly protonated thiourea- and sugar-substituted cyclams and their transition-metal complexes

T. Felder, A. Röhrich, H. Stephan, C. A. Schalley— 2008

Cyclam macrocycles tetrasubstituted with amino-, thiourea-, and sugar-terminated side chains are ionized by electrospray ionization mass spectrometry (ESI-MS) as singly or doubly protonated species or as transition-metal complexes. Their fragmentation behavior is examined in a Fourier-transform ion-cyclotron-resonance (FT-ICR) mass spectrometer by collision-induced dissociation (CID) experiments. Typically, fragmentation occurs within the side chains through a number of different 1,2-elimination reactions irrespective of the absence or presence of a transition metal ion such as Co2+, Ni2+, or Zn2+. A remarkable exception is Cu2+, which induces ring cleavage reactions. This is traced back to an electron transfer from the cyclam nitrogen atoms to the Cu2+ ion. The electron transfer creates a cation-radical within the macrocycle, which induces typical fragmentation reactions such as α-cleavages that lead to fragmentation within the macrocycle. This interpretation is in line with fragmentation experiments on unsubstituted cyclam and its complexes.

Title108
Fragmentation reactions of singly and doubly protonated thiourea- and sugar-substituted cyclams and their transition-metal complexes
AuthorT. Felder, A. Röhrich, H. Stephan, C. A. Schalley
Date20080121
IdentifierDOI 10.1002/jms.1365
Source(s)
CitationJ. Mass Spectrom. 2008, 43, 651-663