Diastereomer Resolution of M₄L₆ Coordination Cages by Ultra‐High‐Resolution Ion‐Mobility Mass Spectrometry

Abstract

Coordination cages can be used for enantioand regioselective catalysis and for the selective sensing and separation of isomeric guest molecules. Here, stereoisomers of a family of coordination cages are resolved using ultra-high-resolution cyclic ion-mobility mass spectrometry (cIM-MS). The observed ratio of diastereomers is dependent on both the metal ion and counter ion. Moreover, the point groups can be assigned through complementary NMR experiments. This method enables the identification and interrogation of the individual isomers in complex mixtures of cages which cannot be performed in solution. Furthermore, these techniques allow the stability of individual isomers within the mixture to be probed, with the T-symmetric isomers in this case shown to be more robust than the C 3 and S 4 analogues.

Automated Structural Activity Screening of β‐Diketonate Assemblies with High‐Throughput Ion Mobility‐Mass Spectrometry

“…CDSA solutions present an analytical challenge as samples contain a dynamic mixture of building blocks, intermediates, and final assemblies [2] . Their identities can be differentiated by their stoichiometry and shape, factors exploited by X‐ray crystallography, diffusion NMR, and ion mobility‐mass spectrometry (IM‐MS) [10–13] …”

“…[2] Their identities can be differentiated by their stoichiometry and shape, factors exploited by X-ray crystallography, diffusion NMR, and ion mobility-mass spectrometry (IM-MS). [10][11][12][13] The categorisation of self-assembling behaviour via traditional bottom-up analysis can lead to an unwieldy amount of manual data handling. IM-MS is particularly well suited to CDSA screening because it is rapid, reproducible, automatable and can differentiate supramolecules based on shape (without time-intensive purification).…”

Automated Structural Activity Screening of β‐Diketonate Assemblies with High‐Throughput Ion Mobility‐Mass Spectrometry

“…[2] Their identities can be differentiated by their stoichiometry and shape, factors exploited by X-ray crystallography, diffusion NMR, and ion mobility-mass spectrometry (IM-MS). [10][11][12][13] The categorisation of self-assembling behaviour via traditional bottom-up analysis can lead to an unwieldy amount of manual data handling. IM-MS is particularly well suited to CDSA screening because it is rapid, reproducible, automatable and can differentiate supramolecules based on shape (without time-intensive purification).…”

Self-assembled Co(ii) and Co(iii) [M2L3] helicates and [M4L6] tetrahedra from an unsymmetrical quaterpyridine ligand

“…While symmetric assemblies are both aesthetically pleasing and relatively straight-forward to design and synthesise using a self-assembly strategy, the selective binding of low-symmetry guest molecules requires encapsulation within low-symmetry spaces to enable a wide range of applications from catalysis, to non-linear optics and biology, [1][2][3][4][5][6] complexity or function. [7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22] Recent developments have allowed the preparation of low symmetry and/or non-statistical mixtures of assemblies either using unsymmetric ligands or heteroligand assemblies using steric (shape complementarity) effects. [23][24][25][26] Quaterpyridine [27][28][29][30][31][32][33][34] ligands are excellent candidates for metallosupramolecular chemistry and recently we have shown that the use of unsymmetrical ligands such as L in combination with iron(II) can result in a complex mixture of up to 12 different assemblies, while the degree of steric bulk on the central ring of the ligand can control the equilibrium formed between [M 2 L 3 ] 4+ helicates and [M 4 L 6 ] 8+ tetrahedra.…”

“…While symmetric assemblies are both aesthetically pleasing and relatively straight-forward to design and synthesise using a self-assembly strategy, the selective binding of low-symmetry guest molecules requires encapsulation within low-symmetry spaces to enable a wide range of applications from catalysis, to non-linear optics and biology, 1–6 complexity or function. 7–22 Recent developments have allowed the preparation of low symmetry and/or non-statistical mixtures of assemblies either using unsymmetric ligands or heteroligand assemblies using steric (shape complementarity) effects. 23–26…”