Artificial and mammalian olfaction and low-coordinate metalloporphyrin complexes
Kemling, Jonathan W.
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Title: Artificial and mammalian olfaction and low-coordinate metalloporphyrin complexes
Author(s): Kemling, Jonathan W.
Director of Research: Suslick, Kenneth S.
Doctoral Committee Chair(s): Kenneth S. Suslick
Doctoral Committee Member(s): Bailey, Ryan C.; Lu, Yi; Luthey-Schulten, Zaida A.
Department / Program: Chemistry
Discipline: Chemistry
Subject(s): colorimetric
porphyrin
Abstract: Part 1 A low-cost yet highly sensitive colorimetric sensor array for the detection and identification of toxic industrial chemicals (TICs) has been developed. The sensor consists of a disposable array of cross-responsive nanoporous pigments whose colors are changed by diverse chemical interactions with analytes. Clear differentiation among 20 different TICs has been easily achieved at both their IDLH (immediately dangerous to life or health) concentration within two minutes of exposure, and PEL (permissible exposure limits) concentration within five minutes of exposure with no errors or misclassifications. Detection limits are generally well below the PEL (in most cases below 5% of PEL) and are typically in the low ppb range for the analytes tested. The colorimetric sensor array is not responsive to changes in humidity or temperature over a substantial range and shows excellent batch to batch reproducibility and long shelf-life (greater than 3 months). Part 2 The sense of smell is arguably the least understood of our senses, and the activation mechanism for olfactory receptors is still unclear. Previous work has suggested that vertebrate olfactory receptors are metalloproteins, utilizing metal ion ligation in an extracellular loop as a primary interaction with odorants. A highly conserved metal ion binding motif, HXXC[D,E], has been found to be present in 62-77% of all mammalian olfactory receptors and an alternative sequence, QXXC[D,E], is present in 76-91% of birds, while neither is found in other G protein-coupled receptors. This suggests an important role for odorant binding to metal ions in olfactory signaling. Part 3 Highly sterically hindered bis-pocket siloxy porphyrins were synthesized to isolate the four-coordinate porphyrin species for the first time. Previous work in the Suslick group has focused on four-coordinate Iron(III) species, however, these porphyrins showed no unique chemical reactivities for small molecule or C-H activation. A number of different four-coordinate species (Manganeese(III), Chromium(III) and Cobalt(III)) with varying electronic properties were synthesized and characterized in an effort to explore the reactivities of these coordinatively-unsaturated compounds.
Rights Information: © 2011, Jonathan Wayne Kemling
Dissertations and Theses - Chemistry