Supramolecular chemistry has developed into a very active and sophisticated field during the last decades, as recognized by the Nobel Prize awarded to Cram, Lehn and Pedersen. It focuses on highly complex self-assembled structures with applications in materials technology, catalysis, medicine and electronics.
In a recent publication in Inorganic Chemistry, Rissanen et. al presented a novel approach for synthesis of supramolecular metallocages. Structural characterization of these cages still represents a major challenge; yet, it is crucial to know the geometry of these complexes to understand their physico-chemical properties. Classically, structural characterization is carried out by cumbersome X-ray crystallography or NMR. In this paper, it was shown that ion mobility-mass spectrometry using Tofwerk’s IMS-TOF is an attractive alternative to these techniques as it is fast, requires only minute samples amounts and allows calculation of collision cross sections directly from ion mobility drift times consistent with the crystal structures and the hydrodynamic diameters.
This “chiral water lily,” a flower-like structure formed from a superchiral coordination complex with 60 well-defined chiral centers is shown to be reversibly transformable to a smaller complex with 30 chiral centers. IM-MS is used to show the presence of multiple conformers and confirm the molecular structure of the complex in combination with other physico-chemical techniques. Quoting from the paper, the authors envision “a broad spectrum of applications in chiral host–guest recognition, enantioselective separation, chiral catalysis or even in applications as membrane channels owing to their amphiphilic character and likely biocompatibility.”
“DOSY NMR, X‑ray Structural and Ion-Mobility Mass Spectrometric Studies on Electron-Deficient and Electron-Rich M6L4 Coordination Cages” Inorg. Chem. 2015, DOI:10.1021/acs.inorgchem.5b01082
“Superchiral Pd3L6 Coordination Complex and Its Reversible Structural Conversion into Pd3L3Cl6 Metallocycles” Angewandte Chemie, 2015 DOI: 10.1002/anie.201506539