Cycloparaphenylenes and Their Catenanes: Complex Macrocycles Unveiled by Ion Mobility Mass Spectrometry.
The insoluble product mixture obtained from cycloparaphenylene (CPP) synthesis from Suzuki coupling and reductive aromatization was analyzed. Traditional mass spectrometry suggests a homologous series of macrocycles with 12 to 84 phenylene units. Ion-mobility mass spectrometry, however, unravels an unexpected complexity of isomers with identical chemical formula, but different topologies. Whereas macrocycles containing up to 30 phenylene units show only one structure, the homologue with 36 phenylene units forms at least four different isomers with significant molecular size differences. They can be assigned to catenanes composed of CPPs with 2×18 and 12+24 phenylene units together with the ordinary [36]CPP macrocycle. Most likely, a trefoil knot of the CPP with 36 moieties is also present. For the first time, catenanes can be elucidated in a simple reaction mixture by analyzing their ions in the gas phase, an analysis which lies beyond the scope of traditional analytical methods.
Max Planck Institute for Polymer Research, Ackermannweg 10, 55128, Mainz, Germany.
Wen
0000-0001-8847-1664
W
Zhang
Max Planck Institute for Polymer Research, Ackermannweg 10, 55128, Mainz, Germany.
Ali
A
Abdulkarim
Max Planck Institute for Polymer Research, Ackermannweg 10, 55128, Mainz, Germany.|Present address: Covestro AG, 51365, Leverkusen, Germany.
Florian E
FE
Golling
Max Planck Institute for Polymer Research, Ackermannweg 10, 55128, Mainz, Germany.
Hans Joachim
HJ
Räder
Max Planck Institute for Polymer Research, Ackermannweg 10, 55128, Mainz, Germany.
Klaus
K
Müllen
catenanes; isomers; macrocycles; mass spectrometry; supramolecular chemistry