Resolution of minor size differences in a family of heteroleptic coordination cages by trapped ion mobility ESI-MS. Issue 29 (28th June 2019) - Ebbert, Kristina E.
Abstract : Trapped ion mobility mass spectrometry shows its power as analytical tool in supramolecular chemistry by discriminating ten heteroleptic coordination cage derivatives, only differing slightly in size. Abstract : We report a complex system of heteroleptic coordination cages based on the combination of four bis-monodentate ligands whose backbones only slightly differ in shape and length. cis -[Pd2 L2 L′2 ] assemblies cleanly form after addition of Pd II cations to a 1 : 1 mixture of two shape-complementary ligands, each. When three or even all four ligands are used in combination, the unambiguous discrimination of all individual species in the product mixture becomes difficult by conventional NMR spectroscopic and mass spectrometric methods. Due to steric constraints, the system is restricted to the formation of ten different coordination cages in total, two of which are isomeric. We show that high-resolution trapped ion mobility mass spectrometry (TIMS) allows the clear differentiation of all ten species. Observed size trends could be readily reproduced by the calculation of theoretical values for collisional cross sections (CCS) from geometry-optimized models.