Pi-extended hypervalent iodine macrocycles and their supramolecular assembly with Buckminsterfullerene

Abstract

A series of valine functionalized supramolecular hypervalent iodine macrocycles (HIMs) with enlarged aromatic cores, including naphthalene and anthraquinone, have been synthesized. Single crystal analysis shows the macrocycles consist of a slightly distorted cyclic planner interior with three carbonyl oxygens from the amino acid residues facing towards the center of the macrocycle and all three alkyl groups above one plane. Owing to the enlarged aromatic core, the naphthalene-based HIMs were successfully co-crystallized with Buckminsterfullerene (C₆₀) into a long-range columnar supramolecular structure. The assembled architecture displays a long-range pattern between HIM and C₆₀ in a 2 : 3 ratio, respectively. Disassembly of the HIMs can be accomplished by adding anions of tetrabutylammonium (TBA) salts that selectively bind with the electron deficient iodine center in HIM systems. A comparative study of the associations constants and the binding energies for different aromatic-based HIMs with TBA(Cl) and TBA(Br) is presented.