The solution and solid state analysis of xylylic di-copper complexes as receptors for encapsulating anions : a thesis presented in partial fulfillment of the requirements for the degree of Master of Science in Chemistry at Massey University, Palmerston North, New Zealand
The investigation into neutral aryl-linked oxime dicopper helicates
encapsulating a number of anions was carried out. Two dicopper aryl-linked
salicyloxime derived complexes were synthesized and studied which
contained either p-xylylic (1) or m-xylylic (2) incorporated spacer groups.
UV-visible spectroscopy was used to determine the binding stability constants
of the anion complexes. Complex binding, encapsulation of anions and the
conformational flexibility of 1 and 2 was supported and ascertained by the
crystal structural data obtained. Receptor 1 expressed an exceptional binding
strength for sulfate in THF where a log K value of 5.5 ± 0.3 was acquired.
Receptor 2 could form both helical and non-helical structures. This was able
to bind bromide selectively in a 2:1 stoichiometry of anion:receptor with a log
K2 value of 9.2 ± 0.1 and showed an unexpectedly high association constant
for the perchlorate anion in a 1:1 stoichiometry with a log K value of 4.6 ± 0.2
(presumably in a helical structure).