Mass Spectrometric Characterization and Gas-Phase Chemistry of Self-Assembling Supramolecular Squares and Triangles

Abstract

A detailed mass spectrometric characterization of self‐assembling polynuclear metal complexes is described. The complexes can only be ionized as intact species under a surprisingly narrow range of conditions by electrospray ionization. Comparison with the results from NMR experiments shows that several solution‐phase features of these squares and triangles (such as trends in bond energies, ligand‐exchange reactions, or square–triangle equilibria) are qualitatively reflected in the gas‐phase data. Consequently, mass spectrometry represents a valuable method for the characterization of these compounds. Nevertheless, the formation of unspecific aggregates during the ionization process occurs and its implications are discussed. Beyond the chemistry in solution, the fragmentation pathways of these complexes in the gas phase have been studied by infrared multiphoton dissociation (IRMPD) experiments. The results of IRMPD studies allow us to draw conclusions with respect to the structure and energetics of fragmentation products. In this tandem MS experiment, reaction pathways can be observed directly which can hardly be analyzed in solution. According to these results, the equilibration of triangles and squares involves the supramolecular analogue of a neighboring‐group effect.

ZnII Coordination Poylmers Based on 2,3,6,7-Anthracenetetracarboxylic Acid: Synthesis, Structures, and Luminescence Properties

“…H 4 ata and azpy were synthesized according to the reported methods. 13,14 Elemental analyses (C, H, and N) spectra for the powdered solid samples were measured on a Varian Cary Eclipse fluorescence spectrophotometer and all the measurements were carried out under the same experimental conditions. The X-ray powder diffraction spectra (XRPD) were recorded on a Rigaku D/Max-2500 diffractometer at 40 kV, 100 mA for a Cutarget tube and a graphite monochromator.…”

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

“…Fragmentation pathways of the metallosupramolecular square, 25 [Pt(dppp)(4,4’-bipyridine)] 4 (OTf) 8 have been studied by Schalley et al by carefully mass-selecting triply-charged squares in the gas phase via tandem MS experiments. 700 Infrared multi-photon dissociation (IRMPD) spectra of Pt(II)-squares in their +3 charged state in the gas-phase have been recorded on a ESI-FT-ICR-mass spectrometer. The mass spectrum showed a doubly charged 3 : 3 complex ( m/z 1443) and a singly charged 1 : 1 complex ( m/z 912) of Pt(II)-corners and bipyridines as primary products.…”

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

“…12,18,19 Unfortunately, CSI sources using liquid nitrogen require sophisticated, custom-made instrumentation (available in one laboratory only) and easily produce solvent adducts. 14,16,17 Conversely, FTICR MS cannot deconvolute the isotope patterns of the intact supramolecular ion from those of superimposed fragments with exactly the same m/z values, a situation encountered with highly symmetrical structures, self-assembled from a large number of identical repeating units; 12,18,19 and neither CSI nor FTICR MS can separate isomeric architectures. These problems make it obvious that alternative analytical methods are necessary to characterize properly supramolecular polymers.…”