Jozef Hodyl PhD Thesis - Theses - Flinders University

CHAPTER 6GUEST MOLECULE INCLUSION STUDIESWITH SILICA IMMOBILISED RECEPTORS6.1 Guest Inclusion with silica immobilised receptor complexes:BackgroundStudies with molecular receptor model 49 in DMSO-d 6 , have demonstrated thesuitability of a three-walled binding cavity for guest molecule inclusion andprompted the present investigation with silica bound receptor complexes. As thepreliminary studies were conducted in an organic solvent, it was expected that thecurrent investigation, which would be conducted in the more interesting aqueousenvironment, might provide some contrasting results regarding binding behaviourbetween host and guest in this medium.As host-guest binding constants for the silica immobilised receptors could not bedetermined by conventional methods due to the difficulty in organising conditions,such that, an equilibrium is established between bound and unbound guest;provisional binding strength was established by evaluating the percent of guestspecies removed from the initial solution after contact with the receptor. Percentinclusion of guest species was determined by UV-Vis spectroscopy and calculated bythe equation% inclusion = − 100where n i is the number of mmol of guest species in the initial solution, n e is thenumber of mmol in the solution at equilibrium, m the mass of the silica material (g)and L the loading of macrocycles on the silica material (mmol g -1 ) to yield %inclusion of the respective guest species.6.1.1 Strategy for guest molecule inclusion with silica immobilised hostsGuest inclusion with silica immobilised host materials was effected by the treatment94