Gradient Tandem Mass Spectrometry Interfaced with Ion Mobility Separation for the Characterization of Supramolecular Architectures

Abstract

Traveling wave ion mobility mass spectrometry (TWIM MS) was combined with gradient tandem mass spectrometry (gMS(2)) to deconvolute and characterize superimposed ions with different charges and shapes formed by electrospray ionization (ESI) of self-assembled, hexameric metallomacrocycles composed of terpyridine-based ligands and Cd(II) ions. ESI conditions were optimized to obtain intact hexameric cation assemblies in a low charge state (2+), in order to minimize overlapping fragments of the same mass-to-charge ratio. With TWIM MS, intact hexameric ions could be separated from remaining fragments and aggregates. Collisional activation of these hexameric ions at varying collision energies (gMS(2)), followed by TWIM separation, was then performed to resolve macrocyclic from linear hexameric species. Because of the different stabilities of these architectures, gMS(2) changes their relative amounts, which can be monitored individually after subsequent ion mobility separation. On the basis of this unique strategy, hexameric cyclic and linear isomers have been successfully resolved and identified. Complementary structural information was gained by the gMS(2) fragmentation pattern of the metallosupramolecules, acquired by collisionally activated dissociation after TWIM dispersion. TWIM MS interfaced with gMS(2) should be particularly valuable for the characterization of a variety of supramolecular polymers, which often contain isomeric architectures that yield overlapping fragments and aggregates upon ESI MS analysis.

Dondorff Rings: Synthesis, Isolation, and Properties of 60°‐Directed Bisterpyridine‐Based Folded Tetramers

“…TWIM‐MS (Figure 4 B) confirmed the presence of a single species by a typical step‐like spectrum with minor peaks at low m / z range, which correlate to fragments of the tetramer. In addition, gradient tandem MS (gMS 2 , Figure 4 C) spectra for tetramer 7 , whereby the +4 state ion was exposed to collisionally activated dissociation at increasing collision energy,39 revealed good stability at energies up to 55 eV.…”

Supramolecular Coordination: Self-Assembly of Finite Two- and Three-Dimensional Ensembles

“…Wesdemiotis, Newcome and coworkers used travelling wave IMS-MS to obtain qualitative conformational information and high-resolution mass spectra for hexacadmium metallacycles. 704, 705 Traveling wave IMS-MS, which enables two-dimensional gas-phase separation and complete deconvolution of the isotope patterns of ions with the same m / z value, facilitates the structural analysis for self-assembled supramolecules. 706 With travelling wave IMS-MS, ions with different charges and shapes are separated based on their drift time in the ion mobility device, thus avoiding isomer superposition prevalent in regular ESI-MS or Fourier transform mass spectroscopy.…”

Direct Self‐Assembly of a 2D and 3D Star of David

“…[24] Thee xperimental isotope pattern of several charge states agreed well with theoretical simulations (see Figure S38). To assess the stability of the 2D Star of David, we carried out gradient tandem mass spectrometry (gMS 2 ) [26] by isolating the 17 + charged ion, followed by collision-induced dissociation (CID). To assess the stability of the 2D Star of David, we carried out gradient tandem mass spectrometry (gMS 2 ) [26] by isolating the 17 + charged ion, followed by collision-induced dissociation (CID).…”