Cocrystallization of pyrogallol[4]arenes with target molecules

Abstract

[ACCESS RESTRICTED TO THE UNIVERSITY OF MISSOURI AT REQUEST OF AUTHOR.] Supramolecular chemistry, in its simplest and broadest description, is the chemistry of intermolecular interactions or chemistry of the noncovalent bond. Supramolecular chemistry is rooted in discoveries, such as the chlorine clathrate found in 1810 by Sir Humphry Davy, and concepts, such as coordination chemistry (1893-Werner) and the lock-and-key concept (1894-Fischer). The broad definition of supramolecular chemistry can be applied to a vast subject range including naturally occurring assemblies, such as proteins and the double helix of DNA. Today, a key interest of supramolecular chemists is the design of functional multi-component systems constructed from smaller molecular building blocks. This research focuses specifically on the supramolecular chemistry of a family of macrocycles called calixarenes, specifically the pyrogallol derivatives pyrogallol[4]arenes. Due to the bowl-like shape of the macrocycles and the presence of 12 upper-rim hydroxyls, pyrogallol[4]arenes have been found to exhibit a number of interesting supramolecular properties. The following dissertation contains the description of advances that have been made using these macrocycles. This work illustrates the expansion of a project dealing with the cocrystallization, and encapsulation of fluorescent reporter molecules with a variety of pyrogallol[4]arenes in different solvent systems. The description of a number of crystal structures that is offered will illustrate how, through thoughtful experimentation, the successful design of a new host molecular capsule was carried out and broadened to include a number of guest molecules. The target molecules have also been expanded from the fluorescent reporters to a variety of possible targets molecules. The solid-state structures discussed include multiple cocrystals of gabapentin, an active pharmaceutical ingredient, and structures containing the organometallic sandwich complex ferrocene.