Studies in materials chemistry : the preparation of surface-oriented multilayered assemblies
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This text describes the synthesis of surface-oriented multilayers based on novel monomeric species. The impetus of this study is to incorporate atypical species and techniques in order to prepare well-ordered assemblies on gold surfaces. These thin films were characterized by one or more of following techniques: grazing angle FT-IR; optical ellipsometry and x-ray photoelectron spectroscopy. First, chemical vapor deposition polymerization was used to prepare surface-oriented monolayers on amine functionalized gold from 4-aminobenzaldehyde and 5-phenyl-1, 3-dioxolane-2, 4-dione. The 4-aminobenzaldehyde showed regular increases in the intensity of characteristic IR absorptions with number of deposition cycles while the dioxolane showed no regularity in this respect. We infer from our data that this technique is a practical way to synthesize highly conjugated polymers. Secondly, we investigated the preparation of surface oriented materials based on host-guest assemblies. Cyclodextrin functionalized gold surfaces could serve as orientational templates for multilayered well-ordered host-guest materials. However, in our study, thiol modified cyclodextrin showed no ability to organize surface multilayers via surface crystallization in the presence of the appropriate host; nor did it show an ability to pre-organize in solution via polyethylene glycol rotaxane formation followed by surface attachment. Finally, surface-oriented organometallic monolayers and multilayers were prepared from alkyne functionalized gold surfaces. Using bis-orthodimethylaminomethyl (NCN) ligands we synthesized two unique surface-oriented organometallic assemblies. Palladium NCN hydrosulfides formed monolayers on gold. Characterization by FT-IR, XPS and ellipsometry show that these species similar to their thiol counterparts. In addition, organometallic polymers were grown from alkyne functionalized surfaces. The thickness of these films, which reached 40 Å by ellipsometry was dependent upon the nature of the alkyne initiator.