Publication Date

2013-07-24

Availability

Embargoed

Embargo Period

2015-07-23

Degree Type

Dissertation

Degree Name

Doctor of Philosophy (PHD)

Department

Chemistry (Arts and Sciences)

Date of Defense

2013-06-28

First Committee Member

Angel E. Kaifer

Second Committee Member

Burjor K. Captain

Third Committee Member

James N. Wilson

Fourth Committee Member

Xiangyang Zhou

Abstract

This dissertation deals with studies of molecular encapsulation and preparation of novel molecular cages. The author begins in Chapter 1 with a short discussion of molecular encapsulation and some of the molecular hosts such as cavitands, carcerands, hemicarcerands, hexamericresorcinarene capsules and molecular cages and then presents more introductory material on a deep cavity cavitand and cucurbit[7]uril since the author’s research is majorly based on these two molecular hosts. The author is interested in the electrochemistry studies of redox-active guests and their electrochemical kinetic changes before and upon encapsulation in aqueous solution so as to mimick the behavior of redox proteins in biological systems or be potentially used for drug delivery. The author carries out a series of characterization experiments such as 1H NMR, ESI-TOF MS, DOSY NMR, COSY NMR, UV-Vis and so on to prove the formation of host-guest complexes before running any electrochemistry experiments. Some experiments fail to provide convincing evidence for redox-active guests encapsulated in the host molecules.Therefore the author does not include these systems in the dissertation. The author gives two encapsulation examples in Chapter 2 and Chapter 3 respectively with tetrathiafulvalene (TTF) and bulky adamantylferrocene derivatives in a dimeric capsule formed by two deep-cavity cavitands. In Chapter 4, the author investigates binding of cucurbit[7]uril with a newly synthesized tris(viologen) derivative guest. Upon viologen moiety encapsulation inside cucurbit[7]uril, the surrounding guest protons that are close to the oxygen portal of cucurbit[7]uril will have strong interactions with the oxygens and show interesting complexation-induced chemical shifts in 1H NMR experiments. The author also reports data on two control compounds to help explain the interesting phenomena. In Chapter 5, the author attempts to synthesize a novel molecular cage glued by “click” reactions. With trial-and-error, the author ends up with insoluble polymers since the “click” reactions are super-efficient and undirected. The results show that the design of the starting materials will affect the formation of the cage molecules and intramolecular reactions must overcome intermolecular cross-linking reactions after the first “click” made. Highly diluted experimental conditions and a suitable template are also important for the successful formation of cage molecules.

Keywords

molecular encapsulation; molecular host; octaacid; redox-active guest; host-guest complex

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