|dc.description.abstract||The work presented in this thesis encompasses the synthesis of novel p-tert
butylcalixarene-based ligands with the overall aim of exploring and understanding their
coordination chemistry. The ligands described have been obtained via substitution and
functionalisation of p-tert-butylcalixarene at one methylene bridge position, the
mechanism of which is discussed in detail herein. Once isolated, these ligands were reacted
with a selection of transition (TM), lanthanide metals (Ln) and 3d-4f metal ion mixtures in
order to systematically study the formation of polymetallic clusters and their prevailing
magnetic properties. This also provided the opportunity to gain insight into ligand
influence over the associated coordination chemistry, all of which was possible through the
growth and X-ray diffraction study of single crystals in each case.
Chapter 1 contains an overview of calix[n]arene synthesis (and related derivatives), with a
particular emphasis on calixarene, its conformational properties, and synthetic
modifications at the upper-, lower-rim and methylene bridge positions. Discussion then
moves to a qualitative description of single-molecule magnets and molecular refrigerants,
highlighting some of the seminal achievements in the area. The final section of Chapter 1
discusses the coordination properties of calixarene, including the formation of metal clusters that represent the foundation of the work presented in Chapters 2 – 5.
Chapter 2 presents the synthesis of 2,2’-biscalixarene prior to discussion of the use of
this ligand in reactions with TM / Ln ion mixtures, the results of which were the isolation of a series of 2,2’-biscalixarene-supported 3d/4f metal clusters. This was carried out
with a particular focus on stoichiometric control over cluster synthesis, which subsequently
afforded novel cluster topologies that are closely related to species already obtained from
previous research within the group.
Chapter 3 covers exploratory cluster formation that was carried out using 2,2’
biscalixarene in the presence of complementary and competitive co-ligands. The co
ligands employed were carefully chosen based on their known metal ion binding
properties, resulting in dramatic changes to the topologies of the prevailing polymetallic
clusters, the structures of which are described in detail.
Chapter 4 describes a modified synthetic procedure that facilitated the isolation of a
family of flexible alkyl chain tethered biscalixarenes. These ligands were then used in
exploratory cluster formation and afforded a series of known cluster topologies when the
length of the alkyl tether permitted this. Structural discussion highlights these similarities
and draws comparison with the TBC-supported clusters presented in Chapter 1.
Chapter 5 focuses on exploratory coordination chemistry that was carried out with rigidly
tethered biscalixarenes. The chapter begins with a brief description of the synthesis of
these ligands before moving on to discussion of the new polymetallic clusters isolated,
highlighting important structural analogies and differences with the architectures described
in Chapters 1 and 4.
Chapter 6 presents a summary of the work included in this thesis, as well as an outlook of
future work to be undertaken in this area.||en_US