Bidentate ligands are a commonly used class of ligands in catalysis that generate highly-active and selective catalysts. Such bidentate ligands, however, often suffer from synthetic challenges, which can be alleviated by the use of simpler monodentate ligands that assemble through non-covalent interactions to mimic the structure of bidentate ligands at the metal center. To produce a strongly assembled catalyst complex, the Hamilton receptor motif was utilized. Hamilton receptors form six hydrogen bonds with complementary guests and have binding affinities for barbiturates of up to 104 M-1 in CDCl3. Complete bifurcation of the Hamilton scaffold produces a modular ligand structure that allows for modification of either end of the supramolecular ligand structure. Similarly, the barbiturate guest can be synthetically altered creating both chiral guests and guests with differing amounts of steric bulk. Both experimental titration data and density functional theory calculations show that steric bulk discourages binding of the guest while a pre-organized host encourages guest inclusion. Electronic effects on the bifurcated Hamilton system were studied by varying the electron donating or withdrawing ability of the benzamide moiety on the host molecule. Electron withdrawing moieties produce more acidic amide hydrogens on the host which are able to participate in stronger hydrogen bonds with the guest resulting in a stronger host-guest complex. The effects of substitutions on the barbiturate guest were examined as well, and increased steric bulk on the guest resulted in decreased affinities with the host. The bifurcated Hamilton receptor ligands were examined in the palladium-catalyzed Heck reaction of iodobenzene with butyl acrylate. Pd2(OAc)4 was used as a control and all reaction yields with the diphenylphosphine ligand-stabilized Pd were greater than or equal to those obtained with Pd2(OAc)4 alone. The reaction rates did not correlate with the determined binding constants, suggesting that phosphine substitution on the guest plays a larger role than affinity of the complex for the guest. Reaction temperatures were varied, and at lower temperatures the yields increased implying that the strength of the hydrogen bonds between the metal complex and the guest does play a secondary role in the catalysis. This dissertation includes previously published co-authored material.

Convergent and divergent strategies for the synthesis of viologen dendrimers with 1,3,5-tri-methylene branching units are presented. The synthesis of 3,5-bis(hydroxymethyl) benzyl bromide was optimized. The analysis of the crystal structure of 1-[3,5-bis(hydroxymethyl)benzyl]-4-(pyridin-4-yl) pyridinium hexafluorophosphate together with PM3 calculations opens an avenue to judge the structure and conformation of benzylic viologen dendrimers. In order to study chemical trigger induced conformational changes, viologen dendrimers were spin-labeled via a divergent approach. 1-(2,4-dinitrophenyl)-4-(pyridin-4-yl)pyridinium hexafluorophosphate was used as the end group to yield an activated dendrimer of the respective generation. The corresponding dendrimers were spin-labeled by reacting the active functionality with 4-amino TEMPO. The products were characterized by ESR (spin-label efficiency) and conventional cyclic voltammetry. Dynamic ESR studies are planned. New trimethylene-dipyridinium dendrimers were synthesized via a divergent approach using 4-tert-butylbenzyl group as the peripheral group. These dendrimers are well soluble in DMF or DMSO as PF6 salts and they act as a host for anthraquinone-2,6-disulfonate (AQDS). They can be stoichiometrically titrated with AQDS as shown by 1H-NMR, DOSY and cyclic voltammetry. Upon loading them with AQDS, the dendrimers undergo first a contraction, they reach a minimum hydrodynamic radius for complete charge compensation and they re-open when overcharging takes place. The contraction is supported by MM+ calculations. Upon stepwise loading of G2 (42 positive charges) with AQDS (2 negative charges), the first 3 molar equivalents (6 neg. charges) occupy the innermost dendrimer shell (consisting of 6 pos. charges), the next 6 equivalents (12 neg. charges) occupy the middle shell (12 pos. charges) and the last 12 equivalents AQDS (24 neg. charges) occupy the outermost shell of the dendrimer (24 pos. charges), as supported by 1H-NMR titrations yielding the magic equivalent numbers of 3, 9=3+6, and 21=3+6+12. Such stepwise radial complexations again in DMSO were further demonstrated using other molecular guests (mono-, di- and trianionic) as well as with on purpose synthesized viologen dendrimers. α,ω-dibromoalkanes were bifunctionalized in two steps to yield alkyl phosphonates with pyridinium, trimethylenedipyridinium, bipyridinium or a sulfonate at their ω end. These compounds were used as surface modifiers to build biomimetic membranes on the pore walls of mesoporous TiO2. Host-guest interaction studies with on purpose synthesized viologen compounds have been performed in collaboration.