Molecules with functional properties, especially ones that display spin crossover behaviour, are becoming increasingly well researched due to their potential applications as the active components in molecular memory, optical displays or sensors.1,2 To this end, a series of Fe(II) coordination compounds utilising imidazolylimine and pyridylimine based ligands have been synthesised and their spin crossover behaviour analysed through a variety of techniques including variable temperature X-ray crystallography, magnetic susceptibility, surface reflectivity and UV-Visible spectroscopy. Light-Induced Excited Spin-State Trapping (LIESST) effects have also been analysed via photomagnetic measurements. Particular attention was paid to the supramolecular interactions present within the solid-state and the effect that these interactions may have on spin crossover behaviour. Subtle changes to the complexes through counter-anion exchange, solvent effects and ligand design were explored and careful structural analysis completed. This study was separated into two distinct categories. The first describes the synthesis, structural characterisation and spin crossover behaviour of Fe(II) dinuclear triple helicates. Four dinuclear triple helicates have been synthesised, three of which display spin crossover behaviour. Weak LIESST effects were observed in two of these examples. Variation in the ligand field strength between the complexes was achieved through modification of the coordinating “head group” and differences between the flexibility of the ligand backbone were also explored. The latter part of this study describes the synthesis, structural characterisation and spin crossover behaviour of novel Fe(II) mononuclear complexes. A series of related ligands which differ in the p-substituent have been synthesised and their coordination chemistry with Fe(II) metal ions examined. Subtle changes to the counter-anion and crystallised solvent molecules were also explored during this study. Five mononuclear Fe(II) complexes were shown to undergo spin crossover and the structural changes associated with the spin-state conversion have been analysed via variable temperature X-ray crystallography and compared with magnetic susceptibility measurements. Two complexes were also analysed for LIESST behaviour and these complexes showed full photo-excitation into the high-spin state at 10 K.

The aim of this thesis is to develop novel receptors for the recognition of anions and ion-pairs. The guest binding and sensing properties of the receptors are studied by spectroscopic and electrochemical techniques. The ion-pair receptors described herein incorporate amide or urea functionalities for anion binding and crown ether moieties for alkali metal cation complexation. In addition, many receptors contain redox- and/or photo-active groups capable of sensing guest binding events. Chapter One introduces the field of supramolecular chemistry. A review of synthetic cation, anion and ion-pair receptors reported in the literature is undertaken, and the formation of selfassembled architectures is discussed. Chapter Two details the synthesis and study of a range of new upper-rim functionalised calix[4]arene anion and ion-pair receptors. The anion and ion-pair binding and sensing properties of the receptors are investigated by ¹H NMR spectroscopy, electrochemistry and luminescence spectroscopy. Two ion-pair receptors display a positive cooperative ion-pair effect, whereby the presence of potassium cations causes an enhancement in the strength of anion binding via electrostatic interactions and conformational effects. Chapter Three centres on ion-pair receptors incorporating an azacrown group for alkali metal cation complexation together with amide functionalities for anion binding. Receptors containing either ferrocene or transition metal dithiocarbamate groups are capable of electrochemically and/or optically sensing the binding of anionic guests. Chapter Four describes disulphide-appended receptors designed for self-assembly onto gold surfaces. A ferrocene- and disulphide-appended calix[4]arene receptor incorporating hydrogen bonding moieties forms self-assembled monolayers on gold electrodes which exhibit a surface sensing amplification in the electrochemical recognition of anions. In addition, the assembly of receptors onto gold nanoparticles is explored with the aim of producing UV-VIS spectroscopic sensors for guest binding. Chapter Five reports the experimental procedures and characterisation for all products. The Appendices provide information on experimental techniques, list the crystallographic data and summarise all the receptors studied.

Thesis (Ph. D.)--University of Texas at Austin, 2007. / Vita. Includes bibliographical references.

Thesis (Ph. D.)--Brigham Young University. Dept. of Chemistry and Biochemistry, 2006. / Includes bibliographical references.

Title from PDF of title page (University of Missouri--Columbia, viewed on Feb 24, 2010). The entire thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file; a non-technical public abstract appears in the public.pdf file. Dissertation advisor: Dr. Jerry L. Atwood. Vita. Includes bibliographical references.

Thesis (Ph. D.)--University of Texas at Austin, 2009. / Title from PDF title page (University of Texas Digital Repository, viewed on July 30, 2009). Vita. Includes bibliographical references.

Thesis (Ph.D.)--University of Western Australia, 2008.

Thesis (MSc)--University of Stellenbosch, 2008. / Bibliography. Also available via the Internet.

Thesis (Ph. D.)--University of Missouri-Columbia, 2007. / The entire dissertation/thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file (which also appears in the research.pdf); a non-technical general description, or public abstract, appears in the public.pdf file. Title from title screen of research.pdf file (viewed Sept. 4, 2007). Vita. Includes bibliographical references.

Thesis (Ph. D.)--University of Missouri-Columbia, 2006. / The entire dissertation/thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file (which also appears in the research.pdf); a non-technical general description, or public abstract, appears in the public.pdf file. Title from title screen of research.pdf file (viewed Aug. 13, 2007). Vita. Includes bibliographical references.