Supramolecular assembly of hypervalent iodine macrocycles and alkali metals.

Abstract

This study explores the solution- and solid-state assembly of phenylalanine-based hypervalent iodine macrocycles (HIMs) with lithium and sodium cations. The metal cation binding of HIMs was evaluated by addition of lithium tetrakis(pentafluorophenyl)borate ethyl etherate LiBArF₂₀ and sodium tetrakis[3,5-bis(trifluoromethyl)phenyl]borate NaBArF₂₄. The electron-rich, outwardly projected carbonyl oxygens of the HIM co-crystalize with the cations into bent supramolecular architectures. Both crystal structures show a pattern of assembly between HIM and metal cation in 2:1 ratio. While association with sodium leads to a polymer-like network, the lithium crystal structure was limited to dimeric assemblies of HIM. In the lithium-coordinating complex, the oxygen-lithium-oxygen bond angle is approximately 98.83°, displaying a closer arrangement of two HIMs. In contrast, the sodium complex exhibits a more open orientation of two HIMs with an oxygen-sodium-oxygen bond angle close to 167.98°. Lastly, a comparative study of association constants and binding energies for phenylalanine-based HIM with LiBArF₂₀ and NaBArF₂₄ are presented.