Jozef Hodyl PhD Thesis - Theses - Flinders University

TMCS is a small molecule that can gain access where a larger molecule, such asGPTS, 32, cannot.Endcapping of the silanised silica material was effected by an adaptation of themethods used by Dudler, 153 and Silva, 209 whereby, Si-GPS, 33, was treated with anexcess of TMCS, 84, in dry toluene and stirred under reflux for three hours withfurther stirring overnight at room temperature, Scheme 4.4.8433 85Scheme 4.4 Endcapping residual silanol groups of Si-GPS, 33, with trimethylchlorosilane, 84,(TMCS).The endcapped silica material, Si-GPS-(TMS), 85, was then filtered, washed withtoluene to remove residual TMCS and water to remove the HCl produced during thereaction. This material was dried in vacuo and stored in a desiccator.4.1.4 Preparation of the silica attached macrocyclic receptor ligandsThe methods used for anchoring the three receptor precursor macrocycles to thesilica attached linker were essentially identical with the only difference being thesolvent. As the two pegylated pendant arm macrocycles 47 and 48 are not soluble intoluene the solvent was changed to acetonitrile. Loading capacity (to be discussedlater) decreased when the reactions were performed in ethanol.Synthesis of the silica attached receptor ligands proceeded by reacting the Si-75