Non-aromatic building blocks for metallosupramolecular assemblies

Slyusarchuk, Valentyna

Abstract

This study investigates the metallosupramolecular chemistry of coordinating ligands that contain a rigid aliphatic unit via the study of their coordination complexes when combined with d- and f-block metal ions. The aim was to investigate whether these aliphatic units would mimic the rigidity of aromatic ligands, to be able to sustain permanent porosity in their subsequent coordination materials, while also observing their geometric diversity. With this goal, ten ligands containing a rigid aliphatic unit were prepared, none of which had previously appeared in the coordination chemistry literature, and from these, twenty-four novel coordination compounds have been prepared and characterised.

The metallosupramolecular chemistry of aliphatic derivates of 4-picolyl ligands was investigated, to gain an initial understanding of the short contacts arising from the aliphatic components of these ligands via Hirshfeld surface analysis. Protonated heteroatoms were most likely to partake in short contacts, followed by the most polarised aliphatic protons, and finally by the most accessible protons.

These observations were then applied to more complex fused-ring tropinone-derived ligands. Functionalisation at the amine and a-positions of nortropinone generated di- and tritopic ligands that yielded polymeric assemblies, including a gadolinium(III) MOF which maintained most of its porosity after exposure to ambient air.

Functionalisation of nortropinone at the amine and carbonyl moieties produced cyclohexyl-bridged ligands, which yielded discrete and polymeric silver(I) coordination cages. The N-aryl ligands exclusively formed truncated tetrahedron M12L6 cages, while the N-methyl-substituted nortropinone yielded a cubic M8L6 cage. The discrete cages were analysed in-situ via NMR techniques, and their behaviour mirrored the solid-state observations.

Finally, a spirocyclic ligand, spiro[3.3]heptane dicarboxylic acid (Fecht’s acid) was prepared, and its coordination chemistry was studied in zinc(II) and ytterbium(III) MOFs, which were compared to analogous aromatic MOFs. The aliphatic MOFs demonstrated a relatively higher thermal stability and reduced interpenetration, however, no preservation of permanent porosity.

Citation

Slyusarchuk, V. (2023). Non-aromatic building blocks for metallosupramolecular assemblies. (Thesis). Keele University

• Thesis Type: Thesis
• Publicly Available Date: Sep 1, 2024
• Additional Information: Embargo on access until 31 August 2024 - The thesis is due for publication, or the author is actively seeking to publish this material.
• Award Date: 2023-03