Study of templation and molecular encapsulation using highly stable and guest-selective self-assembling structures

• Main Author: Chapman, Robert Glen
• Language: English
• Published: 2009
• Online Access: http://hdl.handle.net/2429/7302

The use of a rigid bowl-shaped molecule (tetrol 1) as the building block for the construction of covalently linked and noncovalently linked molecular capsules is presented in this thesis. First, as part of an exploration into the driving forces for formation carceplex 2•guest, the number of guest or template molecules that can be incorporated into carceplex 2•guest was greatly expanded. This reaction was found to be extremely selective towards the template molecule used; indeed, the relative templating abilities varied by six orders of magnitude. Second, the discovery of a reversible self-assembling structure composed of two molecules tetrol 1, which encapsulates a guest molecule in the resulting cavity, is presented (complex 3•guest). This complex was found to have great relevance to the formation of carceplex 2•guest as follows: Complex 3•guest provides organization of two molecules of tetrol 1 about a guest molecule such that the guest acts as a template for nonreversible covalent bond formation with bromochloromethane to give carceplex 2•guest. Complex 3•guest itself represents a new prototype for a family of switchable (by adjusting pH) selfassembling structures that involve molecular encapsulation and is highly guest selective. Third, complex 3•guest led to the discovery of related complexes that differ in the number and type of linkage that interconnects the two bowls of the complex. These complexes, together with complexes 3•guest and carceplexes 2•guest provide good model systems for the study of noncovalent interactions between molecules, as small changes in the template molecule leads to large changes in the stability of the complexes. Finally, carceplex 2•guest, complex 3•guest and some related compounds provided unique environments to study mobility and orientation of their bound guest molecule. Some potential applications of self-assembling structures based on tetrol 1 are presented. [Scientific models]