(373k) Functional Host-Guest Self-Assembled Monolayer

Martin, S. M., Virginia Tech

The immobilization of molecules possessing specific chemical or biological functionality on solid substrates has applications in many areas, but current technique have difficulties in organic synthesis required to produce á-ù molecules with a hydrophilic head-group at one end of the molecule and the desired functional group at the opposite end. Surface modification with a host-guest self-assembled monolayer (SAM) system, which is composed of host molecules attached to the substrate surface through covalent bonds, with cavities for the inclusion of desired guest molecules for the functionalization of the surface, was investigated. Host monolayers are prepared on a Si (100) (Si/SiO2) by the reactions of specific linker-treated surface with sterically hindered long chain primary and secondary alcohols: 1,2-tetradecanediol, 1-phenyl-1-hexadecanol, and 4'-hydroxyhexadecanophenone, and secondary amines: 4-decylamine, and N-phenylhexadecylamine. This is followed by the insertion and exchange of guest molecules, which are attempted at different solvents, temperatures, and concentrations of guest molecules. The resulting host only monolayers and host-guest mixed monolayers were characterized by surface wettability measurements, ellipsometry, Fourier Transform infrared spectroscopy, X-ray photoelectron spectroscopy, and fluorescence measurements, and their chemical stability was also tested under acidic or basic conditions.