A Double Intramolecular Cage Contraction Within A Self-assembled Metallo-supramolecular Bowl

摘要

When isolated in the high vacuum of an ESI-FTICR mass spectrometer, bowl-shaped metallo-supramolecular M_6L_4 assemblies undergo a surprising and mechanistically interesting intramolecular double cage contraction to yield smaller M_3L_2 cages.rnElectrospray ionization Fourier-transform ion-cyclotron-resonance (ESI-FTICR) mass spectrometry is perfectly suited to investigate non-covalent complexes under conditions that eliminate interfering effects from the environment. Since isolated ions are examined, dynamic, intermolecular exchange processes that proceed in solution can rigorously be suppressed in the gas phase. Consequently, tandem mass spectrometry (MS-MS) opens a completely new view on the reactivity of weakly bound complexes. The fragmentation of a simple triply (as well as quintuply) charged metallo-supramolecular square is an example reported previously:2 it proceeds exclusively through one out of several possible pathways, which benefits energetically from a backside-attack mechanism (Fig. 1).