ABSTRACT CTS-9732691 Vinay Gupta/U. of Ill. Funds are sought for the purchase of surface analytical instrumentation for research on guest-host association between self-assembled surfaces and organic adsorbates. The research proposed aims to address fundamental questions regarding the function of receptor molecules immobilized at solid surfaces, and to understand how the molecular organization of receptor layers supported on solid substrates can be manipulated to enhance guest-host interaction with organic adsorbates? Towards this goal, macrocyclic organosulfide molecules containing a receptor cavity will be synthesized for immobilization within self-assembled monolayers (SAMs). Guest-host association will be investigated in solution, and two types of selective interactions will be the focus of the proposed research: one wherein the inclusion of apolar adsorbates is driven by steric complementarity with the receptor cavity; and another wherein polar interactions such as hydrogen bonding aide steric matching. Using mixed SAMs formed by coadsorption of the macrocyclic receptor molecules and n-alkanethiols, the microscopic structure of the immobilized receptor layers will be manipulated. Role of surface density of receptor molecules and steric barriers in accessing the receptor cavity will be explored. To investigate the influence of molecular flexibility, the length and rigidity of alkyl chains that tether receptor molecules to solid surfaces will be varied. For characterization of the structural changes within the SAMs when in contact with solutions, a commercial Fourier transform infrared (FTIR) spectrophotometer will be modified to perform polarization-modulation reflection-adsorption spectroscopy (PM-FTIRRAS). To monitor the rate and the magnitude of guest-host complex formation, an apparatus to perform surface plasmon resonance (SPR) spectroscopy will be designed and set-up. Tangible outcomes of the research proposed are design principles for supramolecular assemblies with ef fective chemical and biosensing functions. ***
