Design and construction of halogen-bonded capsules and cages

Abstract

This thesis describes the design, synthesis and characterization of supramolecular halogen-bonded capsules and cages from multivalent ligands. In the first part of the thesis, an overview to halogen bonding is provided. After discussing the general features of the halogen bonding, the most frequently used halogen bond donors are introduced and examples of their utilization in halogen-bonded systems are discussed. The chapter also presents recent advances made in the field of halogen-bonded supramolecular capsules. The first part of the thesis also includes a review of halogen-bonded complexes involving halonium ions, and a brief introduction to [N···X+···N] halogen bonds is provided along with a few examples of other three-center four-electron complexes. The second part of the thesis outlines the design, synthesis and characterization of halogen-bonded assemblies, capsules and cages based on tetravalent resorcinarene cavitands and tripodal N-donor ligands. The results obtained are described in detail in the five publications. Both halogen bond donors and acceptors were studied. Halogen bond donors functionalized with four haloacetylene moieties were used as tetravalent donors and their halogen bonding ability towards neutral and anionic halogen bond acceptors were studied in the solid state by single-crystal X-ray crystallography. [N···I+···N] halogen bonds were utilized in the formation of capsular assemblies from pyridine-functionalized cavitands. Based on the ligand design, dimeric and hexameric capsules were prepared through their structurally analogous metal-ligand coordination complexes. The formed complexes were characterized in solution and in the gas phase. [N···I+···N] halogen bonds were further applied to the construction of halonium cages from tripodal N-donor ligands. For the first time, crystal structures of supramolecular cages constructed via multiple [N···I+···N] halogen bonds were obtained.