Metallacrown as a host in host-guest chemistry

This dissertation investigated the structural study of host 15-MC-5 complexes and guest organic carboxylates. The metallacrowns were prepared with L-pheHA, S-phenylglycineHA, L-tryptophaneHA, L-3-methoxy-pheHA, and L-naphthaleneHA and studies between the host and the guest were performed in both the solid state and the solution state. Metallacrown compartments for selective guest recognition were prepared with similar length of dicarboxylate guests such as terephthalate, and trans, trans-muconate. The guest mediated compartment structure was reproduced with the metallacrowns prepared with more hydrophobic ligands such as L-3-methoxy-pheHA and L-naphthaleneHA.;Differential guest binding in solution was measured between Gd(III)[15-MC L-pheHA-5] and benzoate, phenylacetate, hydrocinnamate, or phenylalanine isomers in aqueous solution. The binding interactions between these guests and Gd(III)[15-MCL-pheHA-5] are both of hydrophobic interactions and gadolinium(III)-guest coordination bonds. Benzoate, which has the highest resonance effect and inductive effect, showed the highest binding constant (760 M-1), while phenylacetate showed the lowest binding constant (306 M-1). Binding constants of L-phe (70 M -1) and D-phe (60 M-1) versus Gd(III)[15-MC L-pheHA-5] in aqueous solution were similar within error.;The site selection of guests to La(III)[15-MCL-pheHA-5] was considered in both solution and the solid state. The binding constant of benzoate versus La(III)[15-MCL-pheHA-5](370 M-1) shows that the guest is binding to the hydrophobic site of the metallacrown. However, the solid state data from single crystal X-ray diffraction data suggests that the structure of La(III)(benzoate)3[15-MCL-pheHA-5] can be controlled by hydrophobic interactions between the phenyl group of benzoate and the phenyl side chains of the other neighboring metallacrowns which pull the La(III), toward the hydrophobic side. This is unusual since the La(III) normally resides above the metallacrown mean plane toward the hydrophilic side.;The encapsulation rate of lanthanide(III) ions was measured with Ca(NO 3)2[15-MCL-trpHA-5] in methanol. In the UV-vis experiment, La(III) ion showed a faster reaction rate (0.156 L·mol -1·min-1) than smaller ions such as Nd(III) (0.125 L·mol-1·min-1 ), and Gd(III) (0.0735 L·mol-1·min -1).