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Date of Award
Thesis - Pacific Access Restricted
Master of Science (M.S.)
Larry O. Spreer
First Committee Member
Second Committee Member
Charles M. McCallum
Third Committee Member
A radioisotope of rubidium, 82Rb is used in positron emission tomography. Neutral crown ethers and cryptands have been studied as carrier ligands for Rb+ but exhibit low ion carrying capacity and high toxicity. The present study involved investigating a lariat ether containing an ionizable phosphoryl moiety and a lipophilic sidearm. This kind of molecule is expected to be ionized at physiological pH. It should be able to form neutral complexes with Rb+ and may be able to cross the blood-brain barrier.
Molecular modeling of crown ether-alkali metal cation complexes indicates that a macrocycle containing more than 18 but less than 21 atoms can incorporate Rb+ ion in its cavity. Molecular modeling of some of the complexes of phospho-lariat ethers with rubidium using the Spartan'02 software package revealed that a lariat ether containing 20 member macrocycle will probably form the most stable complex with Rb+ion. Also, it was thought that more flexibility could be imparted to the macrocycle if it contains propyleneoxy units instead of ethyleneoxy units which form most crown ethers. Molecular modeling of two phospho-lariat ethers with 16 and 20 membered rings revealed that 20 membered macrocycle may be a better choice due to the side arm's participation in the complexation with Rb+ to a greater extent. Molecular modeling was used to find the bond angles and bond distances in this molecule.
The synthesis to obtain ionizable phospho-bipodands was performed using subsequent benzylation, phosphorylation and hydrogenation steps. The characterization of products was done using HPLC, NMR and ESI-MS techniques. The synthetic scheme used was demonstrated to be plausible and could be used to obtain ionizable phoshobipodands. Extraction using solid phase anion exchange columns proved to be a good clean up procedure for obtaining pure bipodand. This bipodand could be used as a precursor for synthesizing an ionizable 20 membered lariat ether.
Narayan, Urja Vidya. (2006). Synthesis and characterization of phosphorous containing macromolecular polyether compounds. University of the Pacific, Thesis - Pacific Access Restricted. https://scholarlycommons.pacific.edu/uop_etds/640
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