Synthesis and Interfacial Chemistry of Supramolecular Assemblies

This dissertation describes the design, synthesis, assembly, and characterization of derivatives of 7-substituted-2,4,9-trithiaadamantane (Tripod) in regards to their supramolecular chemistries. Using the synthesized Tripod ligands, 2,4,9-trithia-tricyclo[3.3.1.1^3,7]decane-7-dodecylamide and 2,4,9-trithia-tricyclo[3.3.1.1^3,7]decane-7-carboxylic acid 6-ferrocenoyl-hexanoate, the composition and interfacial properties of mixed monolayers were investigated via Polarization Modulation Infrared Reflectance Absorption Spectroscopy (PM-IRRAS), Water Contact Angle (WCA) measurements, and Cyclic Voltammetry (Cv). It was found that perturbations in the monolayers occurred, increasing the degrees of freedom for the attached functionalities with the possibility of forming defects such as tilt domain boundaries. This was verified when the increasing amount of the attached ferrocene end groups at the interface of monolayer and electrolyte solution resulted in a surface charge increase, which is in agreement with the notion that the electrolyte penetration into the monolayer increases.

2,4,9-Trithia-tricyclo[3.3.1.1^3,7]decane-7-carboxylic acid 6-(2-bromo-2-methyl-propionyloxy)-hexyl ester was designed and synthesized as a unique tridentate surface anchor for Atom Transfer Radical Polymerization (ATRP) surface-initiated polymerization. The prepared initiator proved effective in the polymerization of tert-butyl acrylate (t-BA) and dimethylaminoethylmethacrylate (DMAEMA) producing domains (40 ± 5 nm diameter) extending ~90 nm from the surfaces of gold slides. 2,4,9-Trithia-tricyclo[3.3.1.1^3,7]decane-7-octadecylamide was designed and synthesized as a ligand to cap gold nanoparticles. The ability of the ligand to intercalate the alkyl chains of lipids across the nanoparticle surface was investigated. Solid state thermometric analyses showed that a disruption and intercalation across the nanoparticle surface is marked by a lowering of the glass transition state (T_g) of the Tripod capping agent’s alkyl chains. This notion was further confirmed via dispersion tests and ¹H NMR showing a decrease in intensity of the peaks corresponding to the CH₂ and CH₃ of the alkyl chains.

Based on the principles of supramolecular chemistry, polymer nanocapsules were also synthesized and surface modified for the study of guest molecule release. Testing nanocapsules with poly(carboxylate) and poly(ethylene)glycol functionalized surfaces, it was found that the polymer nanocapsules are more effective carriers for negatively charged small molecules in aqueous solutions at pH 7.4. The fast releasing rates of the guest molecules were mostly attributed to the small size of the polymer nanocapsules (~60-100 nm) and the low percent of cross-linker used in this study.